silcone spray as mould release

[virusoverload]

Hi I'd like to start off by saying this is an amazing forum full of wonderful advice (hence why im posting this here)

Ive just ordered some RTV silicone and resin in a starters kit to cast some of my models and was wondering if the Silicone spray lubricant that I own (previously from airsoft maintenance) was suitable as a mould release. I can't see a reason why not but I thought I would check with people who have much more experience than me.

That is if i even need a mould release for a 2 part rtv mould.

thanks in advance

[mangozac]

Nope sorry silicone spray won't do the job. I too thought it might be a good idea very early on, but discovered the hard way that it doesn't work

I recommend just using vaseline (petroleum jelly).

[paulson games]

welcome to the forum

Liquid silcone will bind with itself as it cures so you will need a release agent or barrier agent in between the two halves in order to make a two part mold.

You can use melted vaseline. A number of silicone suppliers also sell brush on liquids that act as a barrier agent. The people I deal with at smooth on sell a spray on mold release from Mann Technologies which they have said can be used when creating a two part mold you just have to make sure you cover the mold face really well.

(it's the same stuff you use as a normal mold release while casting resin)

I use a brush on liquid that I get from http://www.micromark.com it work really well with both their brand of silicone and also the smooth-on brands.

Each company has a slightly differant chemical make up in their products so what works for one brand may not work for every brand so it's always important to test it out first on something that won't get ruined.

Most petroleum lubricants will probably function well as a barrier when making the two part mold, but I can't say for certain as I haven't tested that first hand and every line of silicones varies a bit. The safest route would be to do a very small test piece first.

[virusoverload]

thanks for the info. My kit should be showing up in the next few days or so. looks like ill have to buy some mould release. is moudl wax spray suitable?

also with vaseline (petrolium jelly) how would you use it cos its more of a paste. as you can tell im kinda diving in at the deep end but thats the way you learn the quickest. (i hope lol)

Ive also heard people mention baby powder whie resin casting. what is this used for?

an a it may help this is the kit that I have coming. just enough to get me hooked on the whole thing then i empty my bank account on more supplies im sure.

[paulson games]

I started out with that same kit, it gets the job done for starting out but the resin is really thick compaired to some of the other brands and has a lot of fumes, just make sure to have lots of fresh air avilable. It also has a fairly short working life so that means you'll need to get your mixing and pouring done quick.

Biggest thing to remember is that you'll need some practice and don't give up. I went through my entire first batch of stuff before I had any good casts, had much better luck when I changed brands. (but I also didn't have anyone helping with a forum like this one)


The Vaseline you can heat up in a spoon and a cigarette lighter, as it's warmed it'll become liquid allowing you to brush it nice and thin across the mold face.

You probably are better off using the spray release http://www.smooth-on.com/Release-Agents ... index.html

You'll definately want that for when you are doing your casting as it'll help your molds last about 4-5 times longer.

The baby powder helps keep bubbles from sticking to the mold when you are doing the resin, you put some on and then take all the excess so that only a very faint dusting remains on the mold. When you pour the resin it helps break up the air bubbles that get trapped in the molds.

[virusoverload]

thanks for the tip. also when putting the vaseline on the mold would you put it on the item thats in the mold? just trying to larify everything. now i just need to find a uk supplier of that mould release.

[paulson games]

I usually coat the parts with the release agent as well, just make sure that it goes on thin and doesn't clog up any of the details. (It helps make the part easier to remove when you are done with the mold)


If you are heating up a spoon to melt the vaseline make sure you have gloves on, or have the handle wrapped in a cloth so you don't burn yourself as it'll get hot.

[virusoverload]

thankyou for all the help.

please remember im uk based when answering this
what resin would you recommend. (i dont have that much money for something like this hence the starter kit) you know when ive used up the stuff thats on its way.

also with this starter kit and the resin being a little thicker. ive heard of people using a syringe to force the resin into the mould. do you think this would be a good idea seeing as it has such a short work time.

[virusoverload]

also looks like i may have found a suitable mold release:


does this seem suitable?

sorry for being a paint and asking so many questions i just dont want to ruin everything and put me off it all.

[paulson games]

That looks to be perfect for the barrier agent, says it's intended for rubber to rubber applications.

[virusoverload]

brilliant thankyou. seems like i might be able to put it in an atomizer to make life easier.

[virusoverload]

until this arrives as that shop is out of stock ive opted to use the vaseline method. question ive got fo you now is..... ive seen a video where they add a bit of white spirit to the vaseline to make it liquid and then applied it. will this work and would you recommend it?

[mangozac]

I guess it would work, but I try to avoid white spirit as it stinks! Personally I find the heating in a spoon method works great so would just stick with that.

Make sure you use an old brush for it that won't ever be used to paint again

[virusoverload]

Thanks, and im sure ive got plenty of spare brushes. theres four old ones on my desk now that are solid from PVA

[Anvils Hammer]

Ive previously used this with good results-

http://www.tiranti.co.uk/subdivision_pr ... vision=182

When you are making a two part mold, its vital you apply mold release to the A side, then put the master parts back into it, then pour the B side.

Even with this mold release or similar, you should still smear a thin strip of vaseline down one edge to make it really easy to find the split line and get the mold apart.

AH