RTV Mold Release

[garcia]

A few years ago I read about an engraver who used RTV to make mold impressions of engraved floor plates. I beleive he made a box around floor plate and put white RTV inside on top of plate. I cannot remember what he used as a release for the RTV. Does anybody out there know?
Thanks if you do.

 

[Powderhorn]

Garcia;
I have used Pam, and have heard of using Pledge. Another food for thought, is find a good hoby supply, and they have a silicone mold release. Also you could get from Rio, or IJS.

 

[Mike Bissell]

I make alot of molds and I use no release on the metal floorplates. In fact I wipe them down with acetone to make sure there is no grease, oil, ink, or paint left on the metal before I make a mold. You want all the detail to be in the mold. I use RTV that I get from micro mart and it's called one-to-one, and is pourable. From my experience it will not matter what type of RTV you use it will not adhere to metal.

Mike

 

[Unkl Ian]

I've been making Silicone molds from metal parts the last few weeks,
no mold release necessary.No problem.

Not sure if you need Mold Release,if you were making resin parts from the mold.
But most Silicone will definitely stick to it's self.Even if you use Pam.
Found that out last night,the hard way.

 

[Ron Smith]

I only dust a little talc on the mold and blow it out. It helps a little to release the bubbles that form right next to the rubber mold. You can also spray the mold with a clear lacquer and the lacquer sticks to the molding compound as it won't stick to the silicon mold material either, and also helps give you a bubble free surface. The bubbles come from the chemical reaction of the mixture and occaionally you will get some if you have a situation that traps air around the edges. If you make a deep mold and don't pour it to the full depth this helps the bubbles escape around the edges. I make several excellent copies, finish them out precisely around the edges, and then make another mold from them providing they have no flaws. Then I use a different rubber mold compound (takes longer to set up) and make a gang mold so I can pour many at a time. It takes a little experimention, but it is kind of fun and you can make some really nice displays to give to your clients along with the job you did for them. They love it, and it is a great promotional tool for you. They get a little something extra. I give prints away too at times, if I have made enough on the job. That is good PR and some nice, unique decorations for yours or your cleints home....These are just some ideas to make them more valuable to you and your customers and to serve more than one purpose....Good Luck!!.....Ron S

 

[Tom Curran]

When making the rubber mold, as long as you're using RTV silicone, you do not need a release. Silicone will not stick to anything but itself.

HOWEVER< if it is a Urethane mold material, it sticks to EVERYTHING so bad, you will ruin your master if you don't use release. Urethane vapors are TOXIC. Use adequate ventilation.

Silicone is more expensive, but it's not toxic to use, zero or low vapors, and your parts are safe. I use a PolyTek product PlatSil 71-40, which is clear, enabling you to see where to cut your mold apart when the rubber is cured. It's pricey when compared to urethane, but it's a cheap insurance against damage to your parts or body.