Lime sulfur appears chalky and grey

[Lars Grimm]

Hi All,

I almost exclusively work on deciduous so my experience with lime sulfur is limited to winter sprays. However, I have a few oaks that have some deadwood that needs some preservation and so I have started to apply some lime sulfur. I am using this brand, which says 28% calcium polysulfides which seems similar to that found on smaller bottles at bonsai merchants online.



I premoistened the wood with a little spray bottle and used a small brush to paint it at full strength onto the dead wood. The wood had all been dead for a while and was not fresh green wood. When I apply it, it takes on a chalky appearance and is very grey. I've only ever seen videos of lime sulfur applications but I thought it would be thinner and look whiter. When I use a copper brush, all the grey chalkiness comes off but it doesn't much whiter than before. In fact, there is a reddish tinge. Am I making some fundamental mistake here? Here are a few photos showing deadwood the next day after lime sulfur application and then after using a copper brush.

 

[Bonsai Nut]

When I apply it, it takes on a chalky appearance and is very grey. I've only ever seen videos of lime sulfur applications but I thought it would be thinner and look whiter. When I use a copper brush, all the grey chalkiness comes off but it doesn't much whiter than before. In fact, there is a reddish tinge. Am I making some fundamental mistake here? Here are a few photos showing deadwood the next day after lime sulfur application and then after using a copper brush.

FWIW I find that you can get almost pure lime sulfur if you shop for lime sulfur dip for animals. This bottle costs $12 in the States.





When applying lime sulfur on deadwood, you will initially be left with a very garish, ugly yellow color. In fact, it looks like sulfur The color will gradually fade with time and you will be left with bleached wood.

If you use full strength, the deadwood can be extremely white. Some people mix colorants to tone down the final color (India ink usually) though I find you can adjust your strength of application to achieve the same result. Needless to say, keep it away from any foliage, and it is best to buy only what you can use in one season - once open it has about a six month shelf life since solids will start to precipitate out of the solution.

 

[Lars Grimm]

FWIW I find that you can get almost pure lime sulfur if you shop for lime sulfur dip for animals. This bottle costs $12 in the States.

View attachment 332933

View attachment 332934

When applying lime sulfur on deadwood, you will initially be left with a very garish, ugly yellow color. In fact, it looks like sulfur The color will gradually fade with time and you will be left with bleached wood.

If you use full strength, the deadwood can be extremely white. Some people mix colorants to tone down the final color (India ink usually) though I find you can adjust your strength of application to achieve the same result. Needless to say, keep it away from any foliage, and it is best to buy only what you can use in one season - once open it has about a six month shelf life since solids will start to precipitate out of the solution.

Thanks so much. So, it sounds like the best course of action is to do nothing and just let it fade on its own.

 

[Bonsai Nut]

Thanks so much. So, it sounds like the best course of action is to do nothing and just let it fade on its own.

I actually didn't think your first application looked bad at all. Note that the application of lime sulfur is not primarily for asthetic purposes - you use it to keep your deadwood from rotting, particularly if it is lower on the trunk where it stays wet, or is in contact with the soil (why did I think you were in the UK? LOL!)

 

[Lars Grimm]

I actually didn't think your first application looked bad at all. Note that the application of lime sulfur is not primarily for asthetic purposes - you use it to keep your deadwood from rotting, particularly if it is lower on the trunk where it stays wet, or is in contact with the soil (why did I think you were in the UK? LOL!)

One of the problems with the first application is that it was very chalky so you lost a lot of definition in the wood grain. It just obscured the fine details. It would come off with my thumb.

(Well, there is a Durham in England!)

 

[Bonsai Nut]

One of the problems with the first application is that it was very chalky so you lost a lot of definition in the wood grain. It just obscured the fine details. It would come off with my thumb.

The bleaching doesn't happen instantly. You have to leave it on for it to work.

Your deadwood doesn't have to be on your trees to test application rates. Get a bunch of deadwood from dead branches that fall in your yard, line them up somewhere on your bench, and try different things to them to test application rates, use of colorant or whatever. Then you don't have to worry that you are doing something sketchy to one of your trees.

Also, you can use more than one coat, particularly if you are using a low strength application. Each additional coat will increase the bleaching/whiteness until it looks bone white. However it is as much an art as a science because too much can look really artificial.

 

[Wires_Guy_wires]

Are you sure the wood hasn't been treated? If the LS can't penetrate the wood because it's been treated with some type of plastic or preservative, I'd expect it to act weird.

 

[Lars Grimm]

Are you sure the wood hasn't been treated? If the LS can't penetrate the wood because it's been treated with some type of plastic or preservative, I'd expect it to act weird.

Yes, I can confirm it has not been pretreated.

 

[leatherback]

YOu say you prewet the wood. DId you let the wood take up the water? Or did you just spray it and then more or less directly add the limes ulfur?

 

[Lars Grimm]

YOu say you prewet the wood. DId you let the wood take up the water? Or did you just spray it and then more or less directly add the limes ulfur?

Hmm, actually I just sprayed it with water and then applied the lime sulfur a few minutes later. Maybe that was a problem.

 

[Wires_Guy_wires]

Yes, I can confirm it has not been pretreated.

Cool, also no neem oil treatments?
I've seen wood react like this after I treated it with parafin oil, wax or some other preservatives and then applied LS. To me it looked like the oil or wax formed a barrier inside the wood which caused the lime sulphur to stay on the outside.
Mixing your pre-spray water with some detergent could help with water penetration, most dishwashing soaps will do fine. Apple juice also contains some surfactants but you really don't want those sugars to pile up.

It could very well be that the wood you're treating is so well dried that it closed itself off from water. That's why oak constructions can last for centuries. Natural and perfect drying could have the same effect as preservants.
If you wrap it with some wet towels for a couple days before treating it, I expect the result of a LS treatment to be more pleasing.

I've been able to paint 200 year old oak wood furniture after treating it with a good surfactant and keeping it damp-ish. Before the treatment, the paint just wouldn't stick because the wood was dried and preserved so well that it was basically water and paint repellent for the first 24 hours. I wouldn't expect that to happen outdoors, but you never know.

 

[Adair M]

When I treat my deadwood with lime sulfur, I wet the deadwood thoroughly. Then let it dry a bit, maybe an hour. Then, when I apply the lime sulfur, it soaks in. I apply my lime sulfur at “half strength”, but I’m pretty sure it is much higher concentrated than the stuff you used. When I apply it, it is a reddish color, but as soon as it touches the wood, it turns yellow. It’s only after it dries does it turn white.

 

[leatherback]

When I treat my deadwood with lime sulfur, I wet the deadwood thoroughly. Then let it dry a bit, maybe an hour. Then, when I apply the lime sulfur, it soaks in. I apply my lime sulfur at “half strength”, but I’m pretty sure it is much higher concentrated than the stuff you used. When I apply it, it is a reddish color, but as soon as it touches the wood, it turns yellow. It’s only after it dries does it turn white.

Same here. Which was exactly why I was asking. Was thinking that

the wood you're treating is so well dried that it closed itself off from water