Glaze suggestions

[andrewiles]

I decided to try making some pots. Following ABCarve's approach in his wet slab thread. Complete noob about to start pot #4. I have access to a local studio that does midrange firings. The studio handles the firings -- I can glaze how I want after bisque but otherwise it's out of my control.

Love to get some glaze suggestions from this crowd. I'm know zilch about glazing so I'm going to do some test tiles first. I plan to focus on larger rectangular pots for forest plantings, starting with larches and dawn redwoods. These pots are a bit tall so I'll start shinking the height and elongating the width and length. Up to about 26" on the diagonal for their kiln they say.

Here are my 3 pots so far:


Here are my two clay bodies:


I think I want more subdued, earthy tones. Not glossy or flashy. Browns, grays and tans I think.

Anyone have any favorite glazes or application approaches you think I should try? Has to be fairly simple for my first go at it.

Looking around the interwebs, I'm liking the look of Amaco Matte Shino glazes, such as:

 

[mwar15]

I don’t make my own glazes. I use mason stains and oxides. I like spraying, you can control the thickness better I think. Google it and you can get some good examples on some of the pottery forum

 

[Ericc]

Have a look at glazy.org for selfmade glazes.

 

[andrewiles]

I'm firing a few test tiles tonight. Picked up some Amaco and Mayco glazes at the local store. I'll probably try some stains and eventually some selfmade glazes but I figured I should start out with simple purchased glazes first.

 

[andrewiles]

Is there any particular reason why the inside of bonsai pots are typically not glazed? From what I can tell it's historically just to avoid wasting glaze material. Since the pots are vitrified I don't think there is any water absorption rationale. And the "help roots grip the pot" explanation doesn't make much sense to me since we tie the trees down anyways.

I ask because with my studio's midfire glazing I reason my pots would be a bit more protected from freezing if they are completely covered in glaze. I don't think I'm going to get 100% vitrification.

 

[sorce]

Is there any particular reason why the inside of bonsai pots are typically not glazed? From what I can tell it's historically just to avoid wasting glaze material. Since the pots are vitrified I don't think there is any water absorption rationale. And the "help roots grip the pot" explanation doesn't make much sense to me since we tie the trees down anyways.

I ask because with my studio's midfire glazing I reason my pots would be a bit more protected from freezing if they are completely covered in glaze. I don't think I'm going to get 100% vitrification.

I reckon it's most to do with the difference between straight smooth glass and a bumpy, if microscopically, surface.

It'd be right hard to get a Completely glazed surface, you're probably more likely to reach frost proof without it, depending on the clay.

You can/should buy your own cones to place next to your pots iffin they won't meet your request for one.

Sorce

 

[rockm]

Is there any particular reason why the inside of bonsai pots are typically not glazed? From what I can tell it's historically just to avoid wasting glaze material. Since the pots are vitrified I don't think there is any water absorption rationale. And the "help roots grip the pot" explanation doesn't make much sense to me since we tie the trees down anyways.

I ask because with my studio's midfire glazing I reason my pots would be a bit more protected from freezing if they are completely covered in glaze. I don't think I'm going to get 100% vitrification.

The "may not make sense to you" thing for not glazing the interior makes sense to trees.

Just because trees are tied down, doesn't anchor them completely. The best bonsai pots have clays with "tooth" rough texture that roots can grip. Some potters even score the interiors of their pots with grooves and patterns to give extra anchoring for roots. Glazes are slick on interiors. They allow roots masses to slip around.

Also, as the interior of a pot is filled with roots and soil, it's not visible, so why complicate things unnecessarily and needlessly?

Glaze

 

[rockm]

The "may not make sense to you" thing for not glazing the interior makes sense to trees.

Just because trees are tied down, doesn't anchor them completely. The best bonsai pots have clays with "tooth" rough texture that roots can grip. Some potters even score the interiors of their pots with grooves and patterns to give extra anchoring for roots. Glazes are slick on interiors. They allow roots masses to slip around.

Also, as the interior of a pot is filled with roots and soil, it's not visible, so why complicate things unnecessarily and needlessly?

Glaze

FWIW,

Here are a couple of Don Gould pots with interior scoring on the sides and floor of the pot.

 

[penumbra]

Just because trees are tied down, doesn't anchor them completely. The best bonsai pots have clays with "tooth" rough texture that roots can grip. Some potters even score the interiors of their pots with grooves and patterns to give extra anchoring for roots. Glazes are slick on interiors. They allow roots masses to slip around.

THIS^^^

Looking around the interwebs, I'm liking the look of Amaco Matte Shino glazes, such as:

These are great glazes but they have a serious learning curve. Don't use them until you learn how to use them or you will be disappointed. The only way to learn to use them is to practice on smaller more"disposable" pots. Don't try to learn on pieces that mean a lot to you. You have an very good possibility of ruining a nice pot. After your bisque fire you may like the Eclipse pots with no glaze. Also, glazing dark clays is a challenge that also requires a leaning curve.

I ask because with my studio's midfire glazing I reason my pots would be a bit more protected from freezing if they are completely covered in glaze. I don't think I'm going to get 100% vitrification.

How does your studio define midfire ranges? It should be cone 5 - 6. If your clay bodies are cone 5 - 6 then your pieces will be fully vitrified. You need to know this going in. If your clay body is cone 8 - 10, it will not vitrify at cone 5 - 6.

Those are nice pots.

 

[andrewiles]

THIS^^^

These are great glazes but they have a serious learning curve. Don't use them until you learn how to use them or you will be disappointed. The only way to learn to use them is to practice on smaller more"disposable" pots. Don't try to learn on pieces that mean a lot to you. You have an very good possibility of ruining a nice pot. After your bisque fire you may like the Eclipse pots with no glaze. Also, glazing dark clays is a challenge that also requires a leaning curve.

How does your studio define midfire ranges? It should be cone 5 - 6. If your clay bodies are cone 5 - 6 then your pieces will be fully vitrified. You need to know this going in. If your clay body is cone 8 - 10, it will not vitrify at cone 5 - 6.

Those are nice pots.

Hah! All of my pots are disposable. I do have some Shino test tiles at the studio that should be done now. Need to pick them up. Excited! Reading up on glazes and I think I need to go back and get a chemisty degree.

Yeah, they are cone 5-6. The clays and glazes I'm trying are all designed for that range so I think I'm doing things right. I did get the impression somewhere that vitrification can be a fuzzy thing at mid fire ranges. Mostly vitrified but still a small amout of absorption.

 

[penumbra]

Clay bodies are mixed to be fired at different temperature ranges. A low fire clay may mature at cone 06 and be vitrified. ( and not absorbent) That same clay if fired to cone 6 may produce a molten meltdown and ruin the kiln. A high fire clay that does not mature until cone 10 is not likely to be fully vitrified at cone 6. A clay body developed for cone 6 should be fully vitrified at cone 6.
Absorption is certainly a factor in fire temps and clay bodies that are not matched up, but absorption is more dependent on the clay body itself. There are a few cone 6 clays that I really love that are not suitable for planting pots because they have an absorption rate that is too high even when vitrified. I personally only use clay with an absorption rate of 1% or less when fully matured. The clay that I use for most of my work has an absorption rate of less than .25%. Many potters are happy with an absorption rate of under 2% but there are a couple reasons why I stay under 1%. The first is to produce a frost proof pot. The second reason is because I have found that some pots have problems with glazes cracking and even flaking. If the clay is porous, water can is likely to get under the glaze. This is often the case with cheap Chinese pots. Of course the Chinese make some great pots too that do not have this problem. Certainly don't want to trash Chinese pots, I have some very nice Chinese pots.

A tip to all potters that mid or high fire: don't bring any low fire clay into you studio, even if its free. It all looks the same.