Hoping for help understanding how to replicate a type of container I just saw! (unique 'blocky' container)

[SU2]

I just noticed these two incredible containers in a bonsai mirai video:






Those are VERY similar in style to a more vivid slab-esque container I wanted to make for large specimen, am hoping for any info on building that 'blocky' way (am happy to have found a picture/visual representation of what I had in my head, my sketches on paper are terrible lol)

My only thoughts for how I was going to approach it were to make forms, do it in multiple layers/sessions, while using styrofoam blocks in some of the larger areas to reduce weight (the tree I want to build one for is >1' at the base) Would really like the general ideas used here though because, after seeing this, I'd like to do this style for more than just that single tree, would like to make a few of these blocky ones!

Thanks for any suggestions/tips!!

 

[rockm]

FWIW, a search of Mirai's website shows these are the work of Jonathan Cross.
http://www.jonathancrossstudio.com/
They are wood fired--which probably means that they are slab built stoneware.

 

[SU2]

FWIW, a search of Mirai's website shows these are the work of Jonathan Cross.
http://www.jonathancrossstudio.com/
They are wood fired--which probably means that they are slab built stoneware.

Fantastic thank you!!! I've never gone through Mirai's site I've yet to exhaust sources more relevant to me (his focus is conifers and I'm tropical..) but I do watch the vids he has on youtube just because I like long-lenght / in-depth vids by anyone competent

Am so ignorant of 'stoneware' that I'll be going to wiki after submitting this, looks like I'll have to just figure out a way to mimic that w/ my approach, am thinking styrofoam squares for the cores of the blocks, arrange & secure them w/ steel (rebar or similar) for structure & to keep them in-place, then put lathe over it and apply mortar over it (for the sides, will have a solid bottom)

Am about to go check my updates, am hoping to hear your thoughts on whether a freshly-collected BC can have too-much sun, have been told 'full sun' by multiple people but am really thinking it's doing a disservice to them and saw you mentioning how seedlings dislike full sun... I tagged you so hopefully you see it ;D

 

[Waldo Street Pottery]

Building these pots is not super difficult with some knowledge of clay and how it works. There are plenty of YouTube videos for slab building techniques.

It's the vision and completion that will present challenges. Good luck!

 

[Wires_Guy_wires]

These could be casted with reinforced cement; a metal mesh for support, styrofoam, wood or oiled up cardboard as a casting shape. Use a low sand content and high cement and water, mix in some detergent so that it becomes really rock solid when it hardens. A layer of clear varnish or epoxy would finish it off, if needed.
This summer I'm going to give casting shapes like this a go. I'm thinking about inverse casting, meaning the bottom of the pot will be where I cast cement, and the rim will be at the bottom of the mold.
Styrofoam can be dissolved in acetone/gasoline/organics or burned off for removal. If you dissolve it, the bubbly plastic residue (whwn it hardens again) could make a decent artsy experimental plastic pot or rock as well.
But then again, I have a pottery club wanting to make pots for me so I could always ask them if I can't do it myself. I'm in a luxury position..

 

[Tieball]

I’d make this out of slate...and waterproof rock-weld glue hidden from view. Slate....the type of slate used for walkways or patios around some homes. You might try an less expensive do it yourself project first to see if you really like the look....and have a whole lot of creative fun along the way.

In working with the slate you’ll learn more 3D about the forms if you choose that path. Call it model-making....but you can actually use the model too.

 

[SU2]

Building these pots is not super difficult with some knowledge of clay and how it works. There are plenty of YouTube videos for slab building techniques.

See the thing is I'm not using clay I make my pots from mortar, am under the impression it's apples-to-oranges (though my knowledge of clay pot-building is so low I'm hardly in a position to say)

It's the vision and completion that will present challenges. Good luck!

Thanks! And agreed, I've just been doing forms but have found the completion is the challenge and what separates good/bad products, I'm getting better at makeshift 'inside forms' (to prevent slouching of the mud inside my forms before it hardens) but still getting enough slouch that I spend way more time at the 24hr mark, working them w/ flap- and rasp-disks on the angle-grinder and rasp-bits on the die-grinder, getting the inside-edges refined and evening-out the top lip, they come out of my forms terribly like 1/3" variances in height and stuff like that, several-millimeter differences in wall-thickness, a lot of the time I'm only really correcting the upper-edges of the containers so they'll look good *when planted* and just accept they look crappy when empty!

-------

I’d make this out of slate...and waterproof rock-weld glue hidden from view. Slate....the type of slate used for walkways or patios around some homes. You might try an less expensive do it yourself project first to see if you really like the look....and have a whole lot of creative fun along the way.

In working with the slate you’ll learn more 3D about the forms if you choose that path. Call it model-making....but you can actually use the model too.

That sounds awesome!! I recall slate being quite expensive, it may be beyond my budget but as you mention there's the rough pieces for walkways those probably aren't bad (am just guessing!)
You mention learning more 3D about the forms/model-making, am having trouble telling whether you're saying that in a literal way (like literally making forms for mortar projects by casting against a finished slate project) or abstractly like learning about hands-on 3D shaping? If the latter, or in any case really, I'm real interesting in how you'd work granite, am guessing I can't take my angle-grinder to it to make the shapes I want! Unsure if it's more practical to pursue chipping/scoring&breaking/etc to get the shapes I want, or if I should be looking for the right blades for one of my power-tools (have an 11 or 15A dewalt circular saw, pretty sure there's a blade out there for it that'd go through granite!)

Can only imagine how heavy these'd be if using real stone!! But there's something about real stone that even the best faux stone I've ever seen just can't match yknow?


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These could be casted with reinforced cement; a metal mesh for support, styrofoam, wood or oiled up cardboard as a casting shape.

*Exactly* how I was picturing it!! Using styrofoam (at ~80% the size of my ideal finished-product's dimensions) and putting mid-sized 'rebar' (unsure if it'll be real rebar, may be make-shift or something not steel etc) through it, like using it both to hold the styrofoam blocks in-place as well as to be 'rebar' in the finished product (I know I'd have to have enough of the actual cement biting this for it to be of value, I just want *some* internal reinforcement in such large blocks I don't want all of the reinforcement/structural-pieces to be exterior to the 'inner 80%' that I'd effectively be trying to make out of styrofoam / keep light...would just get the cut styro blocks positioned as-wanted, grooves in them so some spots can have mortar going all the way through (and get the structural bar holding the styro's together!), then wrapping tightly w/ regular stucco-lathe steel mesh, that in and of itself will add a ton of rigidity but will likely add a few thicker (4-5mm minimum) bars along the bottom edges and have them overlap at the corners, to keep the whole thing tight (may do that on the top as well actually, will see once I've got things going!)

Use a low sand content and high cement and water, mix in some detergent so that it becomes really rock solid when it hardens.

What #'s would you recommend? I'd posted on reddit's mortar or masonry subreddit and got 2.5:1 sand:cement ('play sand'/'portland cement', mixed dry right before use and stored w/ desiccants), I've since moved to 2.0:1 and think they come out better that way (based on feel, haven't done any smash tests to compare although I do make smash-pieces of every batch of mud I mix and they're always impressively strong!) Would like to hear your thoughts on ratios, I always hate when it's round #'s (like, 2.2 or 1.8:1 sounds thought-out, 2.5:1 sounds guesstimated, yknow?), have been altering the mix each time and keep finding I want higher portland% in it, will probably do 1.8:1 next mix (may do a session today actually )

Detergent?! Any elaboration would be appreciated! Have heard of its use in terms of tiny amounts added to things to help penetration but you mention 'rock solid' which intrigues the heck outta me as I've got problems w/ air-bubbles, I wish I had better 'inside-forms' so that I could use a slightly more viscous mortar and really fill-out the forms better, get smoother finishes etc but unfortunately the slouch problem is so bad I have to make my mud as dry as humanly possible, like I'll literally get it to 'perfect' and then tamp it to get the sheen to rise, flick some portland on the sheen to dull it, repeat a couple times, til the stuff is as dry as possible w/o compromising sufficient chemical-activation in the Portland, the forms just aren't precise enough to take anything more viscous (am not talking soupy mortar of course, but would be nice to have some extra viscosity!) so very intrigued at the prospect of a dilutant/surfactant like soap being part of the mix!

A layer of clear varnish or epoxy would finish it off, if needed.

Interior or exterior? I see some cons to un-finished interiors but, w/ it absorbing so much moisture that it effectively acts as a 'reservoir' (if the exterior is sealed), I'm starting to think it may not be best to seal the insides...
BUT if you mean the exterior, do you mean an epoxy paint? Have been experimenting w/ watered-down latex paints and colored wax ('crayons' rofl), trying to get interesting color/texture blendings, if you mean exterior I'd definitely want to leave granite raw but for mortar products I dig the look of raw/unfinished but it just makes sense to seal the outside for the moisture-retention.....I dunno, have been struggling w/ the idea of painting most of my containers, I know it's not the norm but I love unfinished cements/mortars and would definitely dig a garden full of unfinished mortar pots & wooden boxes, think it'd have a cool 'basics' look- at the same time I get that it's boring so want to learn to paint something! To that end, I've got white & black paints that I've been watering-down to work with on extra slabs/slices I make (always make 'scrap' pieces from each batch of mud), think that getting good at fading / managing grayscales (and subtle blues or other earth-color accents) is absolutely key for a proper finish to faux rock (once you've gotten down the texture of the outside down! Thinking that first dappling the mud with crumpled tinfoil or crumpled plastic bags would give a good 'base' texture, then cardboard wrapped in plastic (like a stack of several pieces of cardboard at slightly irregular angles to each other) could be pressed-into key places to give a 3D edging to your 'rocks'.....really want to hop on this right now but know it's the type of thing I'll spend hours on and have little/nothing to show for it....gotta do that first step sometime though I guess!!

This summer I'm going to give casting shapes like this a go.

I'd be VERY interested in seeing them, if you happen to remember please tag me or link me, I don't keep-up w/ new posts that often so am likely to miss it and would just love to see what you'd produce!

I'm thinking about inverse casting, meaning the bottom of the pot will be where I cast cement, and the rim will be at the bottom of the mold.

Why would you do it this way? Am trying to picture something like this now, had never considered it before but thinking it could actually be the solution to my slouching problem!!!!!! God I'm so happy you replied I'm already going over inverted casting ideas I think that's going to be a VERY superior way for me to do the regular form-cast containers

Styrofoam can be dissolved in acetone/gasoline/organics or burned off for removal. If you dissolve it, the bubbly plastic residue (whwn it hardens again) could make a decent artsy experimental plastic pot or rock as well.

Styrofoam in gasoline...that can be quite the danger (am guessing you get what I'm alluding to ;p )

TBH I don't see any problem w/ the extra styrofoam that sometimes resides in the crevices around my drainage holes (which are made by using styrofoam 'plugs' that I drill-out afterward, lots of styrofoam gets left behind), I've even heard of people using it as substrate so am not worried about little amounts in areas I can't see and on those I can I'd just flick it off (though the design I've got in-mind would see the styrofoam fully wrapped w/ lathe and then mortar so shouldn't be any visible styro afterward!)

But then again, I have a pottery club wanting to make pots for me so I could always ask them if I can't do it myself. I'm in a luxury position..

Damn, you really are in a lucky spot there!! I've got a little ceramics shop down the street from me, I tried to get some rapport going w/ the lady in hopes of getting my hands on something custom (or getting to hang out and use her equip.!) but didn't really go there, could tell she was just trying to steer me to a 'class package' lol, was trying to get across that I really just wanted a 1-off and couldn't care less how it came out (ie 'whatever style you think is best that's wide/shallow') and think she could tell what I was aiming for but wasn't having it! Good luck w/ getting some nice pots from them, but given how you talk of this stuff I've zero doubt you can do these yourself so may as well go down both paths

Thanks again for replying, great response w/ multiple tips I'll be using for sure!!

 

[Tieball]

I keep my eyes open for cast away stuff...broken pieces of slate. I found enough last year to actually make a walkway if desired. I liked the color...sort of like a grey green. Mostly medium grey. A homeowner was redoing their landscape and just had a pile of slate tossed into the side wooded area. My find. And free. I was lucky....right place at the right time.

For the 3D....I was thinking that actually building one or two out of the slate you’d see exactly what shape entices you. To be honest....I would just make the pot out of the slate. And use them. I like the natural material. I plan to make a couple myself. Summer projects. I plan to use a base of slate also with drilled drainage holes. I have a set of diamond dust hole bits I want to try out on the slate.

Cutting. I cut the slate with an older Makita 7” circular saw with a carbide tip blade. Multipurpose carbide blade. Works well. I cut right through as needed. A carbide tip drill bit works wonders...I go slow...and protect my eyes and breathing. I plan to saw cut and then apply some chisel work, and sanding to achieve the results I want. I’ve cut irregular edges with the blade already. And use my Dremel tool bits to create blending texture. Experimental work. To me...the fun is taking my time and trying...and learning along the way. I’ll sort through my slate this spring.

For the 3D....I think you could cast forms against the slate for the texture of real rock rather than fake rock. I haven’t thought through the forms part really. I was thinking more like....build a slate pot...determine what you like and don’t like with that full size model before actually going further. Again though, I’d probably just use the slate pots and do them well. Perhaps we’ll both experiment this summer and can post and compare results.

I like the look and especially the real feel of the slate. And it weathers beautifully. It has a natural patina that I find exciting.

 

[Wires_Guy_wires]

Woah thats a lot of questions. I'm doing this on mobile and I literally can't see what £'m typing.
Detergent is good for water penetration, it lowers the property of water to "sticking to itself". Was the term adhesion? Anyhow, it makes the bonds stronger in de final product since water can penetrate those finer particles.
A drop pr two should suffice.

As for epoxy or laqcuer, depending on how the final product looks, I'd go for internal at the least. The roots will find a way in crevases and start breaking the pot after a few years. Wetting and drying increases that process. It could add character to the pot.. So in my view, try all 3: none, inside, in and outside.

I'll come back to rhis tonight on a pc.

 

[Wires_Guy_wires]

On a small note in between: less viscous is the way to go to get rock solid cement. My cement is usually as wet as it can be, so that water even comes out of the mixture if you leave it for 5 minutes. It takes 3 weeks to dry but when it does, I can drop a pot and chip off parts of the tiles it fell on.

My numbers vary. The nicest pot I have was made with 5:4:2 (cement, water, sand). I'll see if I can upload it tonight.

 

[Wires_Guy_wires]

Here's a cement pot with the hardcore mixture: virtually no sand and a lot of cement. I've dropped this one so many times, it never broke. Part of the build is shredded newspaper to lighten the material. It was quite hard to get this into shape, because I had to remodel the rim on a daily basis (it was so wet it kept drooping down). This one survived 3 winters already. Now the newspaper is starting to break down, I'm going to give it a layer of cement floor varnish. I wish I had a 'before' pic of the insides, it's really like polished marble. Right now with the frozen varnish, it doesn't anymore.. At the bottom center, a little on the left you can see the marble-like structure it used to have for 2 years (and still does when wet).

Here's another, again with added newspaper (this time a lot, and you can see the fibers if you look closely) and this time some more sand. We can see clearly that the cement has a rougher look to it due to the higher sand content. This one is getting a few layers of clear concrete floor varnish. In the center of the pot, I added a metal mesh for support before casting (chicken mesh/gauze, I don't even know the correct english term for it).

None of these are showcase pots, and they're more of an experiment than anything else. Total cost? Like 5 bucks and a bucket of varnish (which was quite expensive but it'll last decades).

styrofoam in gasoline...that can be quite the danger (am guessing you get what I'm alluding to ;p )

TBH I don't see any problem w/ the extra styrofoam that sometimes resides in the crevices around my drainage holes (which are made by using styrofoam 'plugs' that I drill-out afterward, lots of styrofoam gets left behind), I've even heard of people using it as substrate so am not worried about little amounts in areas I can't see and on those I can I'd just flick it off (though the design I've got in-mind would see the styrofoam fully wrapped w/ lathe and then mortar so shouldn't be any visible styro afterward!)

Oh it can be dangerous, and so does acetone. But if you want to remove something completely, especially styrofoam, it's best to do it thoroughly. Just don't light it on fire. Gasoline+styrofoam can be used as a make shift napalm. But if you let it dampen off completely in a safe location, it shouldn't pose any risk. Just use a little at a time.

As for air pockets: I use an old.. Damn, the flu got my brain unwired and now I keep forgetting words. An automated sanding machine! Right, that was it. Not the ones with the sanding paper rolling around, but a sort of 'vibrating in circles' type. Those are pretty cheap and they let the cement really sink in deep without leaving air pockets. Any vibrating thing would do, except for paint shakers.

Cementing is nothing more than packing minerals in the tightest way possible. Detergent helps water penetrate the finest particles, and helps break them up. This means that you're actually increasing the amount of material per volume, making a tighter stack, and eventually (when done right) it should almost look like marble (which is also nothing more than tightly stacked minerals). If you use little water, the reactions that take place will be superficial at most, it will lead to a more 'grainy' result. The pot will break at the slightest bump of frost due to having a lot of surface area where water can penetrate. Frozen water expands, chips off the outer layers, repeated process, et cetera.

I do advise that when you cast 'bottom side down' to use something to prevent the rim from sludging down. Wood is a terrible material for that (it expands and retracts) but plastics and even cardboard can make fine alternatives as long as you weigh them down a little. Nowadays I love casting pots in potting soil. It creates a rocky outer layer and has a very natural look to it.

Personally, I'm way from done with this. I just do it as I go, making designs after creating a cement mixture. I'm experimenting with wood chips, perlite and a lot of other stuff just to see what it does. Newspaper is a safe one though, however, it does need some shredding and it takes quite some time to completely mix it in.

 

[SU2]

I keep my eyes open for cast away stuff...broken pieces of slate. I found enough last year to actually make a walkway if desired. I liked the color...sort of like a grey green. Mostly medium grey. A homeowner was redoing their landscape and just had a pile of slate tossed into the side wooded area. My find. And free. I was lucky....right place at the right time.

For the 3D....I was thinking that actually building one or two out of the slate you’d see exactly what shape entices you. To be honest....I would just make the pot out of the slate. And use them. I like the natural material. I plan to make a couple myself. Summer projects. I plan to use a base of slate also with drilled drainage holes. I have a set of diamond dust hole bits I want to try out on the slate.

Cutting. I cut the slate with an older Makita 7” circular saw with a carbide tip blade. Multipurpose carbide blade. Works well. I cut right through as needed. A carbide tip drill bit works wonders...I go slow...and protect my eyes and breathing. I plan to saw cut and then apply some chisel work, and sanding to achieve the results I want. I’ve cut irregular edges with the blade already. And use my Dremel tool bits to create blending texture. Experimental work. To me...the fun is taking my time and trying...and learning along the way. I’ll sort through my slate this spring.

For the 3D....I think you could cast forms against the slate for the texture of real rock rather than fake rock. I haven’t thought through the forms part really. I was thinking more like....build a slate pot...determine what you like and don’t like with that full size model before actually going further. Again though, I’d probably just use the slate pots and do them well. Perhaps we’ll both experiment this summer and can post and compare results.

I like the look and especially the real feel of the slate. And it weathers beautifully. It has a natural patina that I find exciting.

Re the slate find- niiiiice!! I've yet to search for some as I'm not starting this project until I've finished making the generic containers for the bulk of my trees (just made another 8 last night actually, well 'formed' them anyways I spend just as long/longer on finishing them w/ my grinders!) Am hoping that generic paver-style slabs aren't that pricey but I really don't need to get much so shouldn't be an issue - what I am worried about is the saw, when you said 'multipurpose carbide blade', what kind of teeth does it have? Obviously carbide lol but 'multipurpose' has me picturing 'regular'-sized teeth which I'd have expected would not work (was picturing either incredibly fine teeth or no teeth like a carbide disk on my angle-grinder, didn't think teeth would work at all on something so hard! My saw is 15A so hopefully it's got enough kick, I already have a carbide blade that I think is 'multipurpose' but the teeth on it seem like they'd be too-large for stone...very interested in what size teeth your blade had!) And re dremel'ing it, I wouldn't have expected a dremel would be able to knick granite! Don't have one yet myself but have 4A grinders (angle-grinder and a long-shaft die-grinder) with rasp disks & bits, I know they're not for stone but I use them on my partially-cured mortar pots and they work great (til the rasps are worn-off and you're left w/ smooth bits!)

Re chiseling- was wondering about this, had pictured slate 'chipping' quite well but wasn't sure how practical chiseling would've been, good to hear that's an option because it's surely going to be a good part of making a 'natural' looking finished product (and I fully agree insofar as real stone > faux, however the tree that I really want a 'stone-style' container for has a trunk >1' wide, so using granite would be out of the question it'd be a hundred-pound container if not heavier lol! Guess I'm picturing using granite to try and mimic what I originally posted here, and/or just making some medium-sized containers, and then using the shape and form of the granite as either a true mold or simply as a 'constant' I can copy off of when making faux stone)

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If you end up going for it please post back here I would love to see!!! I'll certainly post when I get there, may make a new thread if I'm real proud of the finished product but would link it in here for sure

 

[SU2]

Woah thats a lot of questions. I'm doing this on mobile and I literally can't see what £'m typing.

Apologies for that! You've just got such good info I'm trying to glean whatever I can Please please don't feel compelled to post more than you care to, have already gotten a lot of info from you thus far ;D

Detergent is good for water penetration, it lowers the property of water to "sticking to itself". Was the term adhesion? Anyhow, it makes the bonds stronger in de final product since water can penetrate those finer particles.
A drop pr two should suffice.

Awesome! I've heard of things like this before (have even heard it in the context of gardening soils!! Like adding 1 drop so your water penetrates more thoroughly- that's because it's a 'surfactant' right?), when you say 'detergent' I'm taking that as "any soap", hopefully that's accurate/acceptable!! But yeah I wouldn't have thought that'd work here, would've thought the soap would make it 'slippery' where the cement bites the sand, so glad to learn this trick in-general although I can't say I have any issue w/ water penetration in my mixes, surely a result of making small batches by hand, I use a whisk from my kitchen to mix my dry cement//sand and then moisten it, then after mixing tamp-down to get 'sheen' (the water that'll rise when you push-into / float fresh mortar/cement) and put dry cement powder on the sheen, not much but just enough to get rid of it, then consider the mix 'as dry as safely-possible' - dryness makes so much of a difference in how well these come out for me!!

As for epoxy or laqcuer, depending on how the final product looks, I'd go for internal at the least. The roots will find a way in crevases and start breaking the pot after a few years. Wetting and drying increases that process. It could add character to the pot.. So in my view, try all 3: none, inside, in and outside.

Good call on coating the inside, I'd actually had that concern myself before although I was only thinking "they won't leave their pots since the roots will bite", didn't consider them swelling & breaking the pot but can see that! Didn't know wetting/drying cycles were bad for crete though... but yeah I started thinking the 'water reservoir' effect of wetted-mortar was a better feature than sealing the inside so had given up on that idea but now think that was a poor choice, I will seal the insides I wonder what to use? Am not ignorant about paints/sealants in general but, insofar as what's safe for a plant - or whether there's any reason to worry about that at all - I'm totally unaware. I've heard of using 'horticultural oil'(mineral oil, iirc) for things like this but that wouldn't do anything to seal crevices..

On a small note in between: less viscous is the way to go to get rock solid cement. My cement is usually as wet as it can be, so that water even comes out of the mixture if you leave it for 5 minutes. It takes 3 weeks to dry but when it does, I can drop a pot and chip off parts of the tiles it fell on.

My numbers vary. The nicest pot I have was made with 5:4:2 (cement, water, sand). I'll see if I can upload it tonight.

Am confused about the first part here, you say 'less viscous' but then describe a wetter mix - are you advocating a 'slumpier', more liquid mixture? I've found the exact opposite (and would be concerned w/ shrinkage from using excessive water), truly confused on this part (also the 'takes 3 weeks to dry' - I'd have thought that cement would dry at roughly the same rate, like if I made my dry mix, or I made a runnier mix, I'd still expect them to be similarly-cured/dried at day 10)

5:2 cement:sand?!? Holy crap!! I'd been told the strongest was 2.5:1 cement:sand, and in my experiences lately have been bumping it down (last night's batch was made with ~1.75:1 portland:sand), so have been increasing the cement-percentage of the mix but damn I'm so far off-base from you here that I've gotta ask- are there any drawbacks to using such a low % of aggregate in a mixture?

 

[SU2]

Here's a cement pot with the hardcore mixture: virtually no sand and a lot of cement. I've dropped this one so many times, it never broke. Part of the build is shredded newspaper to lighten the material. It was quite hard to get this into shape, because I had to remodel the rim on a daily basis (it was so wet it kept drooping down). This one survived 3 winters already. Now the newspaper is starting to break down, I'm going to give it a layer of cement floor varnish. I wish I had a 'before' pic of the insides, it's really like polished marble. Right now with the frozen varnish, it doesn't anymore.. At the bottom center, a little on the left you can see the marble-like structure it used to have for 2 years (and still does when wet).

Here's another, again with added newspaper (this time a lot, and you can see the fibers if you look closely) and this time some more sand. We can see clearly that the cement has a rougher look to it due to the higher sand content. This one is getting a few layers of clear concrete floor varnish. In the center of the pot, I added a metal mesh for support before casting (chicken mesh/gauze, I don't even know the correct english term for it).

None of these are showcase pots, and they're more of an experiment than anything else. Total cost? Like 5 bucks and a bucket of varnish (which was quite expensive but it'll last decades).


Oh it can be dangerous, and so does acetone. But if you want to remove something completely, especially styrofoam, it's best to do it thoroughly. Just don't light it on fire. Gasoline+styrofoam can be used as a make shift napalm. But if you let it dampen off completely in a safe location, it shouldn't pose any risk. Just use a little at a time.

As for air pockets: I use an old.. Damn, the flu got my brain unwired and now I keep forgetting words. An automated sanding machine! Right, that was it. Not the ones with the sanding paper rolling around, but a sort of 'vibrating in circles' type. Those are pretty cheap and they let the cement really sink in deep without leaving air pockets. Any vibrating thing would do, except for paint shakers.

Cementing is nothing more than packing minerals in the tightest way possible. Detergent helps water penetrate the finest particles, and helps break them up. This means that you're actually increasing the amount of material per volume, making a tighter stack, and eventually (when done right) it should almost look like marble (which is also nothing more than tightly stacked minerals). If you use little water, the reactions that take place will be superficial at most, it will lead to a more 'grainy' result. The pot will break at the slightest bump of frost due to having a lot of surface area where water can penetrate. Frozen water expands, chips off the outer layers, repeated process, et cetera.

I do advise that when you cast 'bottom side down' to use something to prevent the rim from sludging down. Wood is a terrible material for that (it expands and retracts) but plastics and even cardboard can make fine alternatives as long as you weigh them down a little. Nowadays I love casting pots in potting soil. It creates a rocky outer layer and has a very natural look to it.

Personally, I'm way from done with this. I just do it as I go, making designs after creating a cement mixture. I'm experimenting with wood chips, perlite and a lot of other stuff just to see what it does. Newspaper is a safe one though, however, it does need some shredding and it takes quite some time to completely mix it in.

Awesome!! That 'marbling', I get that on some spots as well but cannot figure out any rhyme or reason as to why it occurs, it's usually on the bottom of the container or lower on the sides (like the splotch on the center of yours), does that increase as you up the cement%?

Also you mention using newspaper- I've heard tons about 'papercrete' but always thought it wasn't worth the time, seems the only value is lightening the material and that's not something I care about (not for the small containers at least, maybe once I finish those and start the larger custom ones I'll give papercrete a shot!)

Re air-pockets, I've got a little handheld sander that's as you describe (Black and Decker 'Mouse' orbital palm sander), am unsure just how you mean to use it though, it sounds like you just mean to use the vibration from it to 'settle' the mud into the form more fully?

Re packing minerals/water content, you say "if you use little water the reactions that take place will be superficial at most" - do you suspect I could be using too-little water? I've been using as little water as possible in hopes of reducing shrinkage of the final product, and reducing slouch in the product as it cures - I spend a while being pretty anal about precisely how much slouch/slump my mixture has, I pre-mix my dry powders thoroughly and then add water til I get to *slightly* more wet than I want (at this point, if I press the cement into a ball I get a good sheen of water on top of it - my process is to sprinkle a little dry portland on that sheen and work the mud again) I work it w/ tiny amounts of dry portland (and sometimes a couple drops of water if I go too-dry) until it's just a smidge drier than it'd need to be to give 'sheen' if pressed really hard, which I've been thinking was 'ideal' - I want to be sure I'm reading you right in that ^ passage because it sounds like you're saying a wetter mix is superior (I know it's easier to work a wetter mix but wouldn't have thought it better for anything else)

Re 'upside down' casting, thank you!!! I tried it for the first time last night while doing a batch, it seems a far better way of doing this, will see how they come out when I remove-from-forms later today Biggest problem w/ casting upside-down is how to make the 'inside form', the two that I cast upside-down were forms that I happened to have perfectly-sized styrofoam disks to go inside of, w/o that I don't have a clue how you'd do a proper inside-form, unless you're actually carving/cutting styrofoam to fit for each & every job (although I do have 1 form I use quite a lot so maybe making 1 good, dedicated 'inside form' for it is the way to go!)

And I like the idea of perlite as an aggregate, I've thought of that myself actually and was advised against it but that's just 1 anecdote/recommendation, can't say I believed it was that bad an idea (though I never did try it), I feel like if you used a sieve to just get fines that they'd be superior to sand (because they're 'sharper'), or even if you used larger pieces as aggregate they're still 'sharp' and light as hell (although they'd be equally as fragile!)

Thanks for the thorough replies I really appreciate all the info, wish I'd learned more before starting but you've gotta start somewhere and I thought I was ready (I guess my firsts didn't come out that bad but it's certainly something you get better at quick!)

 

[Wires_Guy_wires]

As for the soap.. soap mighy be the wrong word. Shampoo (the cheapest you can find) or dishwashing detergent have the best results, because indeed they act as a mean to reduce surface tension of water.
In soils its best to use shampoo, it damages less of the microbial life there compared to dishwashing detergent.

Increasing water and cement creates a more watery mixture, so that everything has enough water around it to move and settle slowly, but far more compact. The marbling on the bottom is a result of both gravity and compaction; a molecular stack so tight that minerals start to form veins simply because there is no other place to go. Cohesive forces become pretty strong at this point. More water and cement = more solutes per volume = more water based reactions going on = more response = more cohesion = tighter stacks = longer drying period but nicer looking results.
thats my logic ;-)

Your sander sounds like one fit for the job. After casting, press it against the mold (without sanding paper) and just let it run for a few minutes at different spots. It might even suffice just to press it on the table you're working on. The vibrations let the cement settle in, and air pockets will get the movement of the mixture they need to escape. They will just bubble up.

Ehrm, 2.5:1 and 5:2 is kind of the same. I mean, divide the latter by 2 and you'll have the same relative amount ;-)

Styrofoam cutting is necessary for the inside form. Or some plastic wrapped cardboard, which might last longer. Cardboard is easier to obtain here and van be shaped layer by layer. There are even 3d design softwares that let you print a design sheet by sheet on regular paper; just glue it to some cardboard and start cutting, working as a cardboard 3d printer layer by layer. Add some plastic sheets or wrap, and you'll have a reusable mold.

the only issue I'm dealing with when casting bottom side up, are the "feet" of the pot..

 

[SU2]

[edited-to-add: Thanks a ton for such a thorough reply, have learned a lot in this thread and it's showing in every batch I make ]

As for the soap.. soap mighy be the wrong word. Shampoo (the cheapest you can find) or dishwashing detergent have the best results, because indeed they act as a mean to reduce surface tension of water.
In soils its best to use shampoo, it damages less of the microbial life there compared to dishwashing detergent.

Noted you're from the NL's so our nomenclature could be off here....when I say 'soap' I'm referring to the most basic form of surfactant - you mention damage to microbial life, as I understood it a regular soap does not harm microbial life (not if it's a small % off water that's going down), only 'antimicrobial soap' would (most people are under the false-impression that 'regular soap' kills germs- if it doesn't say that it does, it doesn't, it's only function is mechanical ie as a surfactant to decrease friction on whatever it's applied to.

To me, shampoo is soap plus a bunch of 'fortifiers' (lotions, scents etc) and would be less desirable than the most basic, (ideally unscented) hand/dish soap (and I'd say 'detergent' is "laundry soap", besides scent I'm not sure how significantly this differs from regular soap...I personally use generic antimicrobial soap for almost everything - dishes, showering and laundry- but do have 'regular' soap on-hand as well. No shampoo or detergent in my home ;p )

Increasing water and cement creates a more watery mixture, so that everything has enough water around it to move and settle slowly, but far more compact. The marbling on the bottom is a result of both gravity and compaction; a molecular stack so tight that minerals start to form veins simply because there is no other place to go. Cohesive forces become pretty strong at this point. More water and cement = more solutes per volume = more water based reactions going on = more response = more cohesion = tighter stacks = longer drying period but nicer looking results.
thats my logic ;-)

While I still fail to see how this'd significantly impact drying time, I get you now on the idea behind this (I was confused before because I took it to mean you were using extra water/cement on top of a proper mix, not increasing their ratios within the mix ie reducing sand in essence)

I went to Home Depot looking for 'concrete stain', I've now got it in my head that, given the inhomogeneous nature of the 'stack' in cured mortar, that using penetrating stains would give mottled/marbled/neat effects, was thinking gray-scale or maybe subtle earth-tones, would love to know if you're familiar w/ how that'd go! I didn't get any because they only had gallons (for ~$30) and I'd want something smaller to mess with first considering I've no idea how it'll perform.....am planning to significantly water-down some acrylic/latex paint and see if that doesn't create something similar to a stain!
I LOVE the raw/unfinished look of my pots but, w/ the FL environment and how often I water, they'll be green in months if not treated, I hate the look of solid-color paints on them so hopefully I can find a 'stain'-type solution here!!

Your sander sounds like one fit for the job. After casting, press it against the mold (without sanding paper) and just let it run for a few minutes at different spots. It might even suffice just to press it on the table you're working on. The vibrations let the cement settle in, and air pockets will get the movement of the mixture they need to escape. They will just bubble up.

Gotcha!! Sounds like a great idea, although I've gotta say I think that putting a piece of plywood over my washer&dryer and using those as my vibration-source may be a better approach (I like to work in batches, I've only just begun (slowly) starting custom projects, for now it's about getting all plastic containers off my benches lol

Ehrm, 2.5:1 and 5:2 is kind of the same. I mean, divide the latter by 2 and you'll have the same relative amount ;-)

rofl I was face-palming at my 'error' before even reading- unless you misspoke in your post, you were talking about using much more portland than sand (more than twice as much portland in your mud than sand), the original ratio I started with - while matching yours evenly in a specific numerical sense - is flipped! I was recommended to use 1 part portland to 2.5 parts sand!! So to me your mud is wayyyy cement-heavy, and to you my mud is wayyyy sand-heavy, as far as ratios!)
Would really like to know whether you misspoke or whether you're using more portland than sand (actually, using more than twice as much portland as sand) in your mixes, mine are a little over a third portland yours are majority portland (though as mentioned I've been moving toward a higher portland ratio, was 1:1.5 last time I think portland:sand, I've still never made a mix that had portland>sand!)

Styrofoam cutting is necessary for the inside form. Or some plastic wrapped cardboard, which might last longer. Cardboard is easier to obtain here and van be shaped layer by layer. There are even 3d design softwares that let you print a design sheet by sheet on regular paper; just glue it to some cardboard and start cutting, working as a cardboard 3d printer layer by layer. Add some plastic sheets or wrap, and you'll have a reusable mold.

the only issue I'm dealing with when casting bottom side up, are the "feet" of the pot..

Thanks a lot for that I've been struggling so bad w/ 'inside forms' and the concept of stacking cardboard, layer by layer, and just wrapping/fixing it as a solid unit to fit my outer-form, is just brilliant! No Nobel prize I'm afraid but my hat's off to you, will certainly try that idea the next time I make a batch, I've been using dirt (lined w/ plastic) which still lets it slouch a ton, forcing me to spend more time the next day w/ the angle-grinder than I did making the forms/casting them! (nevermind that I'm flying through rasp & flap disks on my grinders!)

The 3D software you refer to, sorry but am not understanding what you mean- if simple for you, could you throw me a url to show what you mean?

And yeah, 'feet' are the worst I haven't even begun to consider them for inclusion as I'm still wrestling bigger flaws in my pots lol, although with that sharp-as-hell idea of using stacked, wrapped cardboard I very well may be able to include feet!

------------------

Are your containers basically 100% finished when removed from their forms? How long do you wait? Really hoping this cardboard trick can save me from my current approach, I'm literally timing my sessions so that ~15-20hrs later I can remove them from their forms (losing >10% of them in the process...) and use the grinders on them while they're still soft-enough to not smooth a new rasp-bit in a minute or two!

 

[Wires_Guy_wires]

I use way more cement/portland than sand.
And as 2/3 much water as the cement, volume wise. 1 cup of sand, 2 or 3 cups of portland/cement, 1.5-2 cups of water.
It makes a wet slurry, and again, it doesn't dry fast at all.

My drying periods take from somewhere close to 4 days up until 2 weeks. When they're dry, they usually easily pop out of molds.

I'll check for that software tonight, I think google sketchup had an option like that, but I'm not even sure that still exists.
I'll come back at the rest too;-)

 

[Wires_Guy_wires]

As for the 3D software, I found I used Autodesk. I don't know if it's still free, or if it ever was, I only know I never paid for it.
With that 3D software (and corresponding converter) you can print every design layer by layer.
Google sketchup is still on my pc, but it needs updating I don't want to take time for, so that's an unanswered possibility.

If that doesn't work, there's always wood, silicone and plastic. I've never tried silicone though! But it seems like the ideal material for casting, since it's flexible and therefore reusable. Some sillicones can even be baked in the oven without losing their properties.

Noted you're from the NL's so our nomenclature could be off here....when I say 'soap' I'm referring to the most basic form of surfactant - you mention damage to microbial life, as I understood it a regular soap does not harm microbial life (not if it's a small % off water that's going down), only 'antimicrobial soap' would (most people are under the false-impression that 'regular soap' kills germs- if it doesn't say that it does, it doesn't, it's only function is mechanical ie as a surfactant to decrease friction on whatever it's applied to.

Regular "hand" soap can be made out of KOH or NaOH mixed with oil. The bars of soap we all have somehwere laying around.. Or the stuff that you pump from a container. If you have the NaOH type (which is the cheapest, most sold, most used, most preferred) then it shouldn't be used for pots. The sodium (Na) isn't that loved by most plants, that's the #1 reason why plants don't love sea water. It's the surfaction you want, not the dissolving of fats caused by the oil+lye result. That means dishwashing soap/detergent, or shampoo. Shampoo contains a lot of extra chemical stuff that sound very chemical, and they sound very unhealthy. But most of those molecules come from nature, or they are adaptations from natural products. These can usually be broken down easily since 99% of them are carbon based and water soluble. As for dishwashing detergent, it's basically the same. Just don't over use it. A few drops should suffice.
Most of the chemicals in dishwashing detergent are meant to 'capture' salts, like EDTA. That shouldn't bother us a lot, it's the surfactants we are looking for. If you can get a hold of some Tween, it would be even better.


As for dyes, I'm clueless about those. A thin layer of concrete paint on a piece of cloth, or maybe even a sponge would have the same effect, leave some protection and is way cheaper. I'm just a poor guy trying to find a way around the high costs of this hobby. I like to think in alternatives instead of barriers ;-)
Pieces of glass incorporated in the concrete maybe? Pieces of molten plastic? Using transparent or dyed epoxy to fill cracks? I see a lot of potential. More than I can ever do on my own.

Your pots look nice though! You have a lot more than I have right now!

 

[Tentakelaertje]

These could be casted with reinforced cement; a metal mesh for support, styrofoam, wood or oiled up cardboard as a casting shape. Use a low sand content and high cement and water, mix in some detergent so that it becomes really rock solid when it hardens. A layer of clear varnish or epoxy would finish it off, if needed.
This summer I'm going to give casting shapes like this a go. I'm thinking about inverse casting, meaning the bottom of the pot will be where I cast cement, and the rim will be at the bottom of the mold.
Styrofoam can be dissolved in acetone/gasoline/organics or burned off for removal. If you dissolve it, the bubbly plastic residue (whwn it hardens again) could make a decent artsy experimental plastic pot or rock as well.
But then again, I have a pottery club wanting to make pots for me so I could always ask them if I can't do it myself. I'm in a luxury position..

Sounds interesting! Curious about your results with the inverse casting. Will you cast concrete or clay? And show off some pots when you did the clay club the favor

 

[Wires_Guy_wires]

Sounds interesting! Curious about your results with the inverse casting. Will you cast concrete or clay? And show off some pots when you did the clay club the favor

I'll be casting concrete. Clay can be shaped with bare hands, and comes out way better when done by a good pottery person. How do you call those anyways? Potterists? Pottists? Clay workers? Potterers? Potheads? I'm not sure, but you catch my drift.

Something that came to mind: floral foam! It can be shaped by pressing it. No need for cutting, no need for weird tools, keeps its shape and can be used dry and wet.. I'm going to buy the stuff this weekend and make a mold out of it, wrap that in plastic and see how it performs.