Bathroom Silicon Mould - Where did I go wrong

P

Phonemonkey

New Member
New to this forum but loads of info I've already put to good use.

I have tried making a mould using bathroom silicon, glycerin and acrylic paint (a recipe listed elsewhere in this forum).

Problem is, when I try to demould, it's torn and fallen to pieces. Any idea where I went wrong? The mould itself is pliable enough but it tears really easy. I was trying to take a mould of a home made dredd badge made from clay that has dried. Should I have used a release agent or was my recipe just not right?

I've used liquid latex in the past with good results but I get fed up applying layer after layer. I thought using silicon would be a good alternative but I don't want to ruin sculpts every time I use it.

Any suggestions/help would be appreciated.
 
First, make sure it is silicone, some sealants dont contain any.

I have had luck with just using the silicon by itself. Maybe get some vinamold which you can reuse.

Phil
 
Silicone.

What did the recipe call for? Actually mixing these materials together?
 
Bathroom silicone's are different to molding silicone as they need to bond to surface's
I use a clear Aquarium silicone if I need to bond Platnum silicone as it bonds to many Different surfaces including plastic/Resin.

I would source a cheap RTV Silicone, you can get it cheap if you hut around the internet. also if your casting many Times, you want it to last and keep its Original detail.

never buy it in stores as it cost's allot more..
 
KINGLEE79 said:
Bathroom silicone's are different to molding silicone as they need to bond to surface's
I use a clear Aquarium silicone if I need to bond Platnum silicone as it bonds to many Different surfaces including plastic/Resin.

I would source a cheap RTV Silicone, you can get it cheap if you hut around the internet. also if your casting many Times, you want it to last and keep its Original detail.

never buy it in stores as it cost's allot more..
Click to expand...


I'm in the UK as well. Any recommended websites to buy RTV?
 
I used bathroom silicone successfully many, many years ago. I wanted a cheap silicone mold of a lifecast so I could make dupes.

If I remember right I first used a generous amount of mold release on the ultracal 30 lifecast. I took an entire tube of silicone caulk and emptied it into a plastic bucket. It was then thin by adding and stirring in a thinner. Now this was almost 30 years ago, so I'm not sure if I used rubber cement thinner or something else. Which ever I used I did do this outside and was wearing a full respirator. Don't try anything like this with a paper filter mask. They are useless in keeping out vapors.

You don't have to thin out the silicone very much, you want it thick enough not to run or drip. After you get your mixture ready you can use spatulas to coat your positive.

I will try and find the box in my garage that has my old notes and see if I can find the exact formula.

If you try this, experiment with a smaller amount, keep notes and see what works BEFORE you risk your original sculpt or positive. And definitely use a respirator. I can't stress that enough. Even liquid latex in large amounts contains ammonia that will burn the lining of your lungs.
 
Phonemonkey said:
I'm in the UK as well. Any recommended websites to buy RTV?
Click to expand...

Hi.
I Have a supplier who supply's me with very good molding Silicone
at a very good price..

I will PM You the Link:p

The silicone is very good for brush-on & Block molding.
I have had no problems with any bubbles and tearing since using it.
it can be catalyzed to set-up in 1 hour for brush on molding
or 3-5 hours for A block mould.
working time is 15-30mins which is Great for brush-on molding..

with your block mould you will want to use the least amount of catalyst and pour in A thin stream as high as possible..
your mould will last for many many casting's.. :thumbsup
 
KINGLEE79 said:
Hi.
I Have a supplier who supply's me with very good molding Silicone
at a very good price..

I will PM You the Link:p

The silicone is very good for brush-on & Block molding.
I have had no problems with any bubbles and tearing since using it.
it can be catalyzed to set-up in 1 hour for brush on molding
or 3-5 hours for A block mould.
working time is 15-30mins which is Great for brush-on molding..

with your block mould you will want to use the least amount of catalyst and pour in A thin stream as high as possible..
your mould will last for many many casting's.. :thumbsup
Click to expand...

could i get that link too please
 
Haha, me too! My silicone prices always seem high compared to our american friends!
 
1. Needs to be 100% caulking silicon
2. Thin the silicon (i use naptha/shellite)
3. Do it in thin coats
4.after about 2 layers use chucks (kitchen towel things) to reinforce the mould
5. Lots of release


Check me out:
www.facebook.com/steamjunkprops Or Steamjunkprops.deviantart.com
 
KINGLEE79 said:
Hi.
I Have a supplier who supply's me with very good molding Silicone
at a very good price..

I will PM You the Link:p

The silicone is very good for brush-on & Block molding.
I have had no problems with any bubbles and tearing since using it.
it can be catalyzed to set-up in 1 hour for brush on molding
or 3-5 hours for A block mould.
working time is 15-30mins which is Great for brush-on molding..

with your block mould you will want to use the least amount of catalyst and pour in A thin stream as high as possible..
your mould will last for many many casting's.. :thumbsup
Click to expand...

PM'd my thanks. Def.look into it.
 
Alaneye said:
The last silicon I got was from Tiranti, Sculptors' Tools, Materials & Studio Equipment and it was very good and cheaper than the last lot of silicon I had purchased. KINGLEE, any chance I could get that link? Always on the look out for new suppliers.

Al
Click to expand...

Hi.
I will post the supplier up on the site.. as its on Ebay.:facepalm

DWR PLASTICS.

I have purchased the 5.2kg batch many times and it works out very cheap compared to buying from over suppliers.

Let us know how you get on with this silicone as I Enjoy working with it.
just hope it doe'snt sell out now..:cry


also naphtha in the UK is hard to source as i wanted it for thinning out Silicone for airbrushing..
and it will make the silicone set allot slower.:cheers
 
Last edited:
In the caulk molds I've made, I have added about 1/2 ounce of mineral spirits (white spirits) per ounce of caulk (in addition to the glycerin and paint). Thinning it in this way also helps to make spreading the silicone easier. As stated before, using pure silicone is also very important, around here it is labeled as "Silicone 1".
 
KINGLEE79 said:
Hi.
I will post the supplier up on the site.. as its on Ebay.:facepalm

DWR PLASTICS.

I have purchased the 5.2kg batch many times and it works out very cheap compared to buying from over suppliers.

Let us know how you get on with this silicone as I Enjoy working with it.
just hope it doe'snt sell out now..:cry


also naphtha in the UK is hard to source as i wanted it for thinning out Silicone for airbrushing..
and it will make the silicone set allot slower.:cheers
Click to expand...

I can't find that seller on Ebay.

Al
 
Could you PM me as well, please?
Or just post it? There's no RPF rule against linking to suppliers, only individual auctions AFAIK.
 
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