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  #1  
Old 06-07-2006, 10:42 PM
spinkways spinkways is offline
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How can you thicken liquid latex??

Hi Guys n Gals

Me again, doh!

How can you thicken liquid latex?? Can u use flour and water??

All help apprecatied. PS: I know latex is not ideal, but gotta use it up.

Ta
J
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  #2  
Old 06-24-2006, 09:02 PM
spinkways spinkways is offline
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Re: How can you thicken liquid latex??

Hi Guys n Gals

I'm still struggling with finding something to thicken my latex?!! Any ideas??

Here's hoping

Spinkways
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  #3  
Old 07-20-2006, 03:51 PM
SPRINGFIELD SPRINGFIELD is offline
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Re: How can you thicken liquid latex??

I'm new to this forum so I'll just say what I can. I'm assuming that you want to use the latex for making molds. If so you can probably add ceco powder which is sold by cementex. I've tried using rubber powder which is recomended by some latex distributers but the addition of the rubber caused shrinkage problems. I think that most anything else that you might add will cause the same problem. I think things like flower will soak up too much of the liquid in the latex causing shrinkage.
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  #4  
Old 07-22-2006, 02:24 PM
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realsculpt realsculpt is offline
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Re: How can you thicken liquid latex??

use cab-o-sil from www.fxwarehouseinc.com also to thin latex use Distilled water, tap water will make it go moldy. this will work its a thickening agent, also known as air-o-sil, or degausser from paint stores, but fxwarehouse or alcone are the cheapest. you could also try fiberfil, but i dont know where to get that anymore

when using cab-o-sil wear a dust mask and eye glasses, it is lighter than air and gets everyway and is not good to breath, some types are very dangerous, but most are not. do it in a closed room, outside would litterally empty the bag in the airs or in your face (which is bad)
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  #5  
Old 07-24-2006, 04:37 AM
sharry sharry is offline
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Re: How can you thicken liquid latex??

I dont know if you've worked this query out but here's my advice...
I use a thixotropic agent (I get it from the same place I get the latex), it will thicken it quite well and depends on how much you put in...I think there's an optimal amount that you can use, but it tells you this on the bottle.
The other option is to use a talc and that thickens it up but I find it retards the cure time a bit.
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  #6  
Old 07-24-2006, 12:12 PM
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Landseer Landseer is offline
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Re: How can you thicken liquid latex??

One thing to remember if you thicken this stuff up, it still CANT be layered on in heavy coats nor can it fill up pockets and undercuts- it'll never cure there.
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  #7  
Old 07-24-2006, 03:20 PM
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terracotta terracotta is offline
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Re: How can you thicken liquid latex??

You can use talc.

Assuming you use grey talc, it makes the latex grey and less flexible when cured.
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  #8  
Old 07-26-2006, 03:40 PM
spinkways spinkways is offline
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Re: How can you thicken liquid latex??

Hi
Thanks for your replies.
Sharry, u mention a 'thixotropic agent'. do u know where I can buy this, I live in Queensland Australia. My providers of latex do not sell thickener.

All help appreciated.

Spinkways
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  #9  
Old 07-26-2006, 04:54 PM
SPRINGFIELD SPRINGFIELD is offline
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Re: How can you thicken liquid latex??

I'm wondering how much latex you bought. I'm no expert on latex but I've bought a lot of differen't brands. I don't believe you should have to use a thickner in good latex and when I get bad thin latex I just don't use. I can't bring myself to throw it away but I don't try to use it either. Kind of like trying to make a silk purse out of a sow's ear kind of thing. Basically 20 coats of latex gives me a 1/6 inch thick mold. That's a lot of work but I believe that it's just the way it is.
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  #10  
Old 07-26-2006, 08:00 PM
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Re: How can you thicken liquid latex??

Quote:
Basically 20 coats of latex gives me a 1/6 inch thick mold. That's a lot of work but I believe that it's just the way it is.
2 coats of thixotropic silicone puts 1/4"-1/2" on in a couple of hours and fills all undercuts solid, and that's just the way THAT is
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  #11  
Old 07-26-2006, 11:06 PM
SPRINGFIELD SPRINGFIELD is offline
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Re: How can you thicken liquid latex??

Thanks Landseer sounds good to me. How does the silicone hold up to casting concrete and where can I get some because I'd realy like to try it. I live in Burbank California. Also I"m moving to the philippines can you get the silicone shipped internationaly?
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  #12  
Old 07-27-2006, 12:07 PM
nep75 nep75 is offline
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Re: How can you thicken liquid latex??

Quote:
Originally Posted by SPRINGFIELD
Thanks Landseer sounds good to me. How does the silicone hold up to casting concrete and where can I get some because I'd realy like to try it. I live in Burbank California. Also I"m moving to the philippines can you get the silicone shipped internationaly?

Silicone is available many places - Polytek, Smooth-On are 2 at least - I know there's a ton more out there. Ball Consulting is in Tempe, AZ and they sell Polytek's silicone. I bet a lot of the places out there would ship internationally if you couldn't get it locally.

Depending on your shore and how you treat your mold, silicone could outlast latex. Latex is really used now a days for special effects and for the companies who make those big fake rocks (like for pool waterfalls and surrounds). The rock people use it for its stretchiness I think.

That's my 2 cents on it.

~ N
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  #13  
Old 07-27-2006, 12:31 PM
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Re: How can you thicken liquid latex??

Quote:
Originally Posted by nep75
Silicone is available many places -
I can't imagine that a product like this wouldn't be available locally anywhere, I mean it's not like the USA is the ONLY country in the world that has sculptors who make molds!
I use QUantum- http://www.quantumsilicones.com/

Quote:
Depending on your shore and how you treat your mold, silicone could outlast latex. Latex is really used now a days for special effects and for the companies who make those big fake rocks (like for pool waterfalls and surrounds).
Silicone doesn't stick to anything, I don't use a release. I don't DO a lot of concrete and in fact I'm happy to stay AWAY from it as much as I can, it's achore to mix, a chore to cast in molds, it takes 2 days of sitting in the mold to harden enough to peel the rubber off without risk of breaking off sharp corners and fine details, it's heavy as solid rock, it is WEAKER than hydrocal plaster and it's only advantage at all is it can be used outdoors and be built into walls.
Latex was used years ago because it was CHEAP, and it WAS cheap when it was something like $12 a gallon, and that was pretty much all there was beside aginate and a few other less strong/suitable rubbers. There was black tuffy rubber but it doesn't last either.

Then came silicone and RTV stuff but the prices were up there, but now the picture has changed- they have to import that natural latex rubber for latex and since it comes from rubber trees as well as places that can have political and other issues- the supply (and the cost) could be disrupted or severely damaged by any number of things.

The silicone has none of that and now the cost per gallon (plus one quart to compensate for the loss of real volume due to evaporation of the solvent) is now near that of silicone- especially when you figure in your TIME painting on 20 coats of this stuff plus the cost of having to add cab-o-sill to thicken it in every coat but maybe the first 2-3. It also makes mother shell building much more timeconsuming and difficult dealing with undercuts that cant be filled with latex.
One thing about latex that one can get used to is it's tear strength- you can't tear it, so if you are used to just "yank-ripping" the rubber off the casts this will not "work" on non latex rubbers you CAN tear it if you get rough with it, but I'll never use latex again.
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  #14  
Old 07-27-2006, 01:51 PM
SPRINGFIELD SPRINGFIELD is offline
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Re: How can you thicken liquid latex??

Thanks everybody especially Landseer and Nep75. I'm going to order some silicone right away. I'll check out that website http://www.quantumsilicones.com. Thanks again.
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  #15  
Old 07-27-2006, 08:07 PM
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Re: How can you thicken liquid latex??

Quote:
Originally Posted by SPRINGFIELD
Thanks everybody especially Landseer and Nep75. I'm going to order some silicone right away. I'll check out that website http://www.quantumsilicones.com. Thanks again.
Good job then, if you like thixotropic for vertical surfaces they have the cat 2 blue thixotropic as well as the non thixotropic. I have tried both, the non will still mix up as a nice heavy bodied batch, it really didn't want to RUN like syrup or anything. I mixed both cats together and varied it a bit. The thixo cat used alone will give you a brushable rubber that will stay on vertical surfaces.
You have PLENTY of working time with this- maybe 45 minutes or longer, unlike the Polytek 74-40 polyurethane which tends to start gelling up and setting on you, this QM140 silicone has a long working life and it only GRADUALLY starts to get a little thicker but you still have loads of time to work it.
I like to start with an acid brush and get the stuff in the details and coat the whole model and then let it sit for maybe 30 minutes and then add a much heavier layer on and let that sit an hour. I prefer to do it with 3-4 applications (though you CAN apply it in any thickness all at once too) as I am used to that method, and it's easier to control how much you are applying and where. Make sure you pay particular attention to building up on the corners, points and edges because the action of brushing the rubber on naturally tends to pull it away from those areas, so I always lay on a lot of extra rubber just on the corners and edges to finish up.

You can fill up undercuts totally solid- 1/2" ? an inch ? the stuff will cure overnight in any thickness.
Most important too is accurate measurement of part A and the catalist, you would get 10# of base and 1# of catalist- about a gallon and a quart worth in the size I normally order. Make sure you mix it WELL, completely, and thoroughly scraping down the sides of the mixing bowl, transfer to a clean bowl, mix a bit more and you are ready.

I use cheap hard and softer plastic - Rubbermaid style quart and larger sized bowls, salad bowls etc I get at Duckwalls usually for about a dollar each, and I found a couple of varnished wood spatulas there for a dollar each and those work great for batch mixing. The cheap disposable acid brushes and the cheap disposable "chip" natural bristle brushes work well and since the silicone doesn't gell up suddenly etc you can usually mix a couple or more batches up and use the SAME brushes as you work.

I also mix several batches for larger pieces and do them in sections, as long as the stuff is still tacky then additional applications will stick, it stays tacky more than an hour, so there's plenty of working time.
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  #16  
Old 07-28-2006, 11:06 AM
SPRINGFIELD SPRINGFIELD is offline
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Re: How can you thicken liquid latex??

Thanks Landseer for all the generous information. You are so very helpful and experienced. I look for all your posts and read them all the time. I'm going to order some today and can hardly weight to get it. Yesterday I found some old silicone that I bought in 2002. Well you know the rest. At least I made a test batch this time instead of puting it on a sculpture. Thanks again for all your help.
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  #17  
Old 07-28-2006, 12:23 PM
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Re: How can you thicken liquid latex??

Quote:
Originally Posted by SPRINGFIELD
Thanks Landseer for all the generous information. You are so very helpful and experienced. I look for all your posts and read them all the time. I'm going to order some today and can hardly weight to get it. Yesterday I found some old silicone that I bought in 2002. Well you know the rest. At least I made a test batch this time instead of puting it on a sculpture. Thanks again for all your help.
Sure thing Springfield, those of us in the sculpture game a long while have been through all the bad stuff you can think of- defective products, products that don't work as claimed, accidents, screwups both minor and major and you name it. Over the course of the years most of us have tried innumerable different products, techniques and methods, some of these work well for certain individuals and not others and vice-versa, but I can tell you that there probably isn't a person here who wants someone else to fail.
As can be imagined this forum and others like it get their share of people who have no real lasting interest or their own ideas how things should be and will listen to no one, so when we say use/do "this" or don't do/use "that" because... it's due to the fact that we have done or not done those things and have suffered the consequences in some way and sure don't want someone else to do the same!

I'm h appy that is seems you are sticking with it and us and are serious, so while you get the materials lets see some pictures of what you are doing before you start applying the rubber, I'm sure suggestions and ideas will flow there and we'll do what we can individually to help you out, but you of course have to do the work and we can only offer suggestions and ideas remotely instead of hands-on, which isn't always the greatest but better than nothing.
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Old 07-28-2006, 06:03 PM
SPRINGFIELD SPRINGFIELD is offline
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Re: How can you thicken liquid latex??

Thanks Lanseer for the encouragement. I got an E-Mail back from Quantium Silicone today and tomorrow I'll call them a see how they want me to send the money. They said it will take about 5 days to get to me in California which is pritty fast. About my sculpturs, I seem to have a bad habbit of not finishing things but there arte a couple of models which are comming along so I'm going to post them here if I can. I realy like gothic and architectural sculpture and I am amazed how good those artists were. I would love to be able to do sculpture like that. One of the pictures is of a greenman plaq that I'm working on , It needs some eyes and a little more work on the leaves etc. The other is a greenman face that I plan to use as a planter. Both are in the5 to 8 inch range. The planter I'm making out of wax. The other one is Roma plastilina.
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  #19  
Old 07-28-2006, 06:51 PM
nep75 nep75 is offline
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Re: How can you thicken liquid latex??

Springfield, just to add on to what Landseer is saying...

Good for you for doing a test run. Silicones don't have a long shelf life even unopened. If you are using Roma, beware of the sulfur if it's a sulfur based oil clay. Platinum based silicones will not set right (for the most part) against sulfur clay. The tin based ones will if the clay is sealed (and maybe if it's not, i've not used the tin based).

Landseer - just a side not the 74-45 (i think that's the rubber you mentioned, don't have time to look right now) is a polyurethane, not a silicone. About half the price as silicone but has to be released and not recommended for casting a lot of resin of plastics. I concur with the latex, too long to make a mold.

Good luck! Practice makes making molds a lot easier.

~ N
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Old 07-28-2006, 07:27 PM
SPRINGFIELD SPRINGFIELD is offline
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Re: How can you thicken liquid latex??

Thanks nep75 about the advice about the roma it looks like I'll find a use for my leftover latex after all. I finaly got my pictures in my last post so you may want to see what I'm doing. The other pictures I tried had too many pixels. Thanks again for all your help.
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  #21  
Old 07-31-2006, 01:29 AM
spinkways spinkways is offline
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Re: How can you thicken liquid latex??

Hi Guys n Gals

Very interesting and informative!

Springfield, I'd love to know how u get on.

With using silocone, I read you have to mix it up, it does not come as one liquid. So when u have made a batch up, can you re-seal the silocone in an air-tight box, then leave it again for a day, then use it again?

So what u are all saying is that instead of using 12 layers of liquid latex to paint a 7 inch model, u only need 2 - 4 layers of silocone?

Also, is silocone safe, or do you have to wear gloves and mask etc?

I look forward to all replies.

Still a novice!!

The Spinkways
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Old 07-31-2006, 01:34 AM
spinkways spinkways is offline
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Re: How can you thicken liquid latex??

Hi
Me again!

Another small problem Iv got.

I made a latex mould of a white/cream small china-like model. The model after me making the mould has come out a bit dis-coloured. Is that because of the latex staining the model or it pulling paint off of it?

Either way Im in trouble as i borrowed the model!! Doh!

Thanks
The Spinkways
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  #23  
Old 07-31-2006, 01:49 AM
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Re: How can you thicken liquid latex??

Quote:
Originally Posted by nep75
Silicones don't have a long shelf life even unopened. If you are using Roma, beware of the sulfur if it's a sulfur based oil clay.
I believe they say 6 months shelf life is their guarantee, that's typical.
The plasticene I use has no sulphur, it's never reacted with either the polytek or silicone.

Quote:
Platinum based silicones
As before- DON'T buy platinum cure, they are very sensitive to moisture and other thing, get the TIN cure.

Quote:
74-40 rubber you mentioned, don't have time to look right now) is a polyurethane, not a silicone.
I know the polytek 74-40 and 74-30 is polyurethane- used them for years till they stuck me with a bad batch and the replacement batch was no better and they made me feel like it was MY fault till they did the batch test at the plant and found one part was bad. I found older molds 2 year old or so starting to tear easy, they must have changed something in the makeup of the formula.

That was when someone HERE suggested I switch to Quantum silicone.

Quote:
About half the price as silicone but has to be released and not recommended for casting a lot of resin of plastics. I concur with the latex, too long to make a mold.
Polytek 74-40 is HALF the price? last time I checked about 3 weeks ago it was MORE expensive!

From Polyteks site:

Poly 74-40 6lbs.
Code:Poly74-40-6
Price: $65.63


They WERE 10# now they seem to be reduced to 6# kits, the Quantum QM140 silicone is about $118 but for a 10# pail of base plus the 2# of catalist- 12#, so the Polytek would cost $121 for the same amount.

The 74-30 you get either 4# or 16# choices, either way it's a lot more than half the cost today;


Poly 74-30 4lbs.
Code:Poly74-30-4
Price: $51.93


Poly 74-30 16lbs.
Code:Poly74-30-16
Price: $124.89
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  #24  
Old 07-31-2006, 11:35 AM
SPRINGFIELD SPRINGFIELD is offline
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Re: How can you thicken liquid latex??

I might be the latex. I made multiple latex molds off a hydrostone model that I sculptured. I only sealed it with wax. Anyway each time I used the model to make a latex mold off of it got a darker and darker brown.
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  #25  
Old 07-31-2006, 12:18 PM
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Re: How can you thicken liquid latex??

Quote:
Originally Posted by SPRINGFIELD
I might be the latex. I made multiple latex molds off a hydrostone model that I sculptured. I only sealed it with wax. Anyway each time I used the model to make a latex mold off of it got a darker and darker brown.
If the latex starts turning brown or pinkish, it's a sure sign it was contaminated by something on the model- usually a copper bearing substance like gold paint or plating.
People think they are permanently and effectively sealing materials by spaying on Krylon or lacquer- basically making it like a layer of GLASS that's impervious to everything and this is simply not true. You spray lacquer or varnish on wood thinking it "seals" the wood from moisture and prevents warping by keeping out the humidity, when in fact all it does is slow the moisture down- it still penetraits the "sealer"

Same thing with the latex, for starters- because it has ammonia in it, it is a mild solvent to a certain degree, also, the action of spraying on a few light coats of Krylon etc misses areas the spray can't get into- deep pockets and undercuts, incised lines- it gets blown right back up and out of those areas.
You can't put it on too heavy either or you lose details and surface texture.
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