Mold making question

[CheddarMelt]

Hello I had a question for the casters out there in model land, I was wondering if you can use silicone rubber that is in a caulk gun to make a mold with?

I was going to see if the silicone rubber stuff in a caulk tube would stick to the master part once it was dry?Because I noticed in the quote below that it says non-porous and if painted,well the part is painted with testors paint and is a resin part master.

I have the casting resin and I was wanting to see if this idea would work,I have a resin kit that has one part that broke and the kit is no longer available and it is a phaser gun that broke and there are two,1 broke,1 not
broken,I was going to use the one that is not broken and make a dup of it.

I noticed this quote from another thread talking about molds,and the person said the following:

For ultra-cheap molds, there's always silicone bathtub caulk. Just make sure that A) you get stuff marked "100% silicone", and B) your parts master is non-porous, and if painted and/or puttied, free of water based or weak solvent based paints/putties, as the carrier solvents in the caulk can dissolve some of them enough to bond the silicone to the master. If the caulk is too thick to brush on without trapping air, it can be thinned with naphtha.

It's cheaper & works better than latex, but takes a long time to dry, and gets quite fumey in the meantime.

Any help would be most helpful,thanks.

[CheddarMelt]

No takers on this question? Wow,I thought with all the smart resin casters out there someone would know about this,am I wrong?

[modelbaseguy]

Empireman, this should work as long as you use a good release agent. Personally, I like to use petroleum jelly thinned 1 to 4 with paint thinner (not mineral spirits). You can airbrush this mixture on in a couple of coats or mix it 1 to 1 and brush it on. The bad thing is that the stuff in the caulk tubes is really thick and it is going to be a pain in the rump to work with.

If you only need one or maybe two copies then may I suggest getting one of those keepsake sets that allow you to make castings of your childs hands or feet. You can pick these up at Wal-mart or any craft store. The mold agent is algenate so it sets up quick enough, it captures all the detail and is really easy to work with. The only thing that I am not sure of is if it will work with resin, perhaps someone else can kick in with that info. Good luck.

[vaderman]

I concur with modelbase guy. You can use it, though I woul sonly use it for small molds. And yes, you MUST use a release agent or it will stick. You may want to try Smooth-on's OOMOO 25 or 30. Get a trial kit for $22. Youc an get several molds out of a trial kit.

Scott
AW Studios

[Darth Humorous]

…Personally, I like to use petroleum jelly thinned 1 to 4 with paint thinner (not mineral spirits).…

O.K., enlighten me. Just what IS the difference between paint thinner and mineral spirits?

Mark

[DLMatthys]

... I was wondering if you can use silicone rubber that is in a caulk gun to make a mold with?

It was a thing I tried about 20 years ago...Track pads for a M60A2 Tank...by the hundreds!

ugh...feelin' old now.

[Darkov]

Found this with a Google Search.....I havn't tried it yet. But it sounds promising if you only need to make a short life mold.

Thinning Silicone Caulk
Sources on the internet indicate that Distilled water, Naphtha, Toloul or charcoal lighter fluid can be used to thin silicone caulk in a tube. One suggestion was to mix 50:50 Naphtha : Silicone Caulk to about the consistency of honey and paint on. These need to be tested.

Hope that helps you out.

Pete

PS....Found this tread on another site....http://www.sculpture.net/community/showthread.php?t=661
very useful tips.

[TER-OR]

I'd be careful with those organic solvents in proximity to styrene.

I've used silicone caulk when I needed just a couple copies of shallow pieces.
And the petroleum jelly is a definite must - both as cover for the part when you coat with caulk and coat the silicone before you pour resin.

[Sparky]

You should find someone who can do a onesees twosees mold for you if it is a special kit for you and you need the part. Like for me if it was a Babylon 5 kit.

There are several folks out there who can pop a mold for you. If it is flat on one side with no loops or other features that require a 2 part mold, a single open face mold is quick and easy for someone wih the RTV and vaccum pump/pressure pot. cost is usually the rubber and resin and some time.

[CheddarMelt]

Well I found a Hobby Store that carried the Alumillite RTV Silcone Mold Rubber,very good stuff. Only 4 hours and it is ready. I also found some cheap Resin that is great,it is also made by Alumillite.

It is Called Amazing Casting Resin,it is a 1-1 mix and for $15.00 you get 16oz of it.Which is not bad for beginners like myself on a budget and who only needed to cast a broke part,LOL.

I wanted to thank everyone for responding to this,I got desperite and went to the Hobby Store on a chance they might carry something.

[macfrank]

Well I found a Hobby Store that carried the Alumillite RTV Silcone Mold Rubber,very good stuff.

It's excellent stuff - I wish it were cheaper.

It is Called Amazing Casting Resin,it is a 1-1 mix and for $15.00 you get 16oz of it.Which is not bad for beginners like myself on a budget and who only needed to cast a broke part,LOL.

The Aluminite stuff gets poo-pooed a lot by others, but the RTV that they sell is one of the best, and their resin may have some issues, but it gets the job done.

I just started playing with a wax compound called Flexmold. It's a flexible wax that lets you make fairly simple molds. Plus it's reusable. I'll write it up and post some pictures this weekend.

Frank

[Sparky]

The RTV stuff from Alumilte seems to be great stuff. It is a little stiff so under cuts may die faster than the other RTVs. But I can pressure cast it even when it was not vacuum degassed! Very impressive.

The resin the stores sale is useally the 7 minute cure time, which means you have about 3 minutes (new) to mix it. And big pieces will get scolding hot! Also kills the mold very quickly.

If your making gribblies of a few small parts you can't beat the cure time, you'll be able to mix a little & cast and mix & cast. . .In one night you can get a pile of parts, if you're casting without pressure casting. Once you add the time to fill a larger mould or moulds and put them into a pot, you'll want to get their slower set resin, or any of the other brand slower set resins.

[CheddarMelt]

Once you add the time to fill a larger mould or moulds and put them into a pot, you'll want to get their slower set resin, or any of the other brand slower set resins.

Any brand suggestions on an inexpensive slower setting resin?

[Sparky]

I use Smooth-on but I don't know that it is cheeper or better than Alumilte or Tap Plastics. I think Umi said Tap Plastics stuff is good and inexpensive. Getting two 1 gallon jugs of resin starts impacts shipping costs so if you find someone local that will help.

BTW there is different hardness resins, smooth-on makes stuff that can me milled and is really hard. One of our club members works in a machine shop and they gave it a try for something. They took the left over and wailed on it with a ballpin hammer. No effect.

I use the smooth cast that cures white. It takes coloring pretty well, has some flex to it but its still hardere than styrene. I'll get the number tonight (310 I think)

[modelbaseguy]

…Personally, I like to use petroleum jelly thinned 1 to 4 with paint thinner (not mineral spirits).…

O.K., enlighten me. Just what IS the difference between paint thinner and mineral spirits?

Mark

I have no clue but I do know that there IS a difference. I was told to use Paint Thinner specifically by probably the best in the casting business so that is all I use. I guess you could try the mineral spirits if you wanted?