Latex drying time

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Owencc

New Member

• Oct 18, 2017

• #1

So i'm slush casting a latex mask with a resin mold and i was wondering how long to let the latex dry in between coats (i'm only on the first coat)

Also if i thinned down the next layer with water (if that would work) would it interfere with the last none thinned down layer?

 

Predatoj

Well-Known Member

• Oct 19, 2017

• #2

A lot longer than a plaster mold because there is no where for the moisture to go. Why would you want to add water? I wouldn't do that, there's no reason to and you will increase drying time. Latex is a natural product, the more water and ammonia added the lower the quality. But be warned, layering latex is not the best way to go because it does delaminate, especially if it's thin coats.

 

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Owencc

New Member

• Oct 19, 2017

• #3

I've never used latex before and i saw a video where someone thinned it down with water to make it easier to slush around in the mold, i couldn't really slush the latex at it's normal state so i had to brush it in and i'm afraid that i made some spots too thick. Also i noticed the latex delaminating is there a way to stop that at all?

 

Predatoj

Well-Known Member

• Oct 19, 2017

• #4

Latex by its very nature is unwieldy. Its not man made so it does what it does. Ammonia is added so that it doesn't spoil (as it's a natural product) and water is added so it can be slushed. Adding water will cause it to be really thin when it dries this will exasperate any delamination. I don't think it can be prevented. But usually you want thick layers, if your initial layers are too thin as the latex shrinks it will be deformed from the original shape. Casting silicone is much better really. It doesn't shrink and chemically cures, but is much more expensive.

 

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Owencc

New Member

• Oct 19, 2017

• #5

Yeah I get what you mean the layer I put in is already peeling away. Do you think slip casting it would work fine with a resin mold?

 

Predatoj

Well-Known Member

• Oct 19, 2017

• #6

It will always come away from the mold as it dries due to shrinkage, this is normal but if it's too thin the original shape will flatten out. So you need the initial layer thick. I think some people have had success with resin molds but it's far from ideal.

 

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Owencc

New Member

• Oct 20, 2017

• #7

Okay but do you think slip casting would work like filling it up and pouring it out after a couple hours. I know it would be a lot longer because of the resin but would it work at all?

 

Predatoj

Well-Known Member

• Oct 20, 2017

• #8

In my view this wouldn't work because the moisture has no where to go. The way it works in a plaster mold is the water is absorbed through the surface of the plaster leaving behind a thick skin of latex, after several hours you pour out the excess. In a resin mould it would just sit there evaporating out of the opening. The length of time it would take negates the whole process.

By the way, the reason people add water to latex for the initial slush is to reduce bubbles ruining the finish, they then fill the mold with undiluted latex but this only works in s plaster mold. I prefer to de-gas the latex in batches in a vacuum chamber. I would consider ditching latex in favour of silicone.