2 years ago#1
Anne
Guest

Hello
I've made various latex molds for casting cement. The last ones I made however, have all been disintegrating after only a few casts, and from areas that are not complicated (i.e. flat surfaces). The first 1-5 layers are coming apart. The mold itself has around 20 layers.
Has this happened to anyone else? I'm using a different brand but other than that I'm not sure what I might have done or what might be causing this. Very frustrating!
Thanks in advance!

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2 years ago#2
mickpearson
Guest

HI ANNE. i am talking to someone at the moment and i did mention to them about using direct heat to dry latex. it should be avoided.did you use heat by any chance anne.what happens when you do this is you are drying one layer at a time so the latex does not nit together. so im only guessing that you might have done this. but i need you to let me know if this is the case. if not we will think of something else

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2 years ago#3
Anne
Guest

Thank you very much
I didn't use direct heat between layers (though good to know that I shouldn't, in the past I've used a hair dryer to speed up drying, I never had problems with those molds). The first layers were thin and I waited a few hours between each one, maybe 5-8 hours on average. The space I am working is cool (but not close to freezing) and I usually have the door open for ventilation, I was wondering if that might have been an issue.

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2 years ago#4
mickpearson
Guest

HI ANNE. your spot on.that's what the problem is. each layer has been given to long in between coats. and has cured and this happens also when you use heat. you are curing each coat and latex does not stick to cured latex. as someone suggested to someone they cut up latex gloves. to thicken the latex mould they where making. so i had to reply to that and tell them not to do that. latex thickener is all that is needed but if you have the patience you don't have to thicken the latex at all but its handy if your in a hurry cause latex is a pane to work with but i like it.

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2 years ago#5
Anne
Guest

Hi Mick
Thanks so much, though I have to admit I'm really surprised, I had thought that you wanted to have the latex layers dry between applications (though have read, and always followed, not to let it dry for a couple days or else it will cure completely and not stick to the next layer). I wonder if this new brand I'm using dries faster, as previous ones I've made I waited even longer between coats. Sigh. Always an adventure
thanks again

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2 years ago#6
mickpearson
Guest

HI ANNE. only let the latex semi dry between coats.and you can keep some thickened latex in another container to thicken vulnerable areas.like deep pockets on some models or just paint it all over and be a little more generous on the pocket areas.

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