Silicone Mold Making

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#1

Hi,

I would like to make a mold out of silicone, but w/out significant amount of layering, most is pretty soft for the reasonable priced. So far, the hardest I’ve found is probably around 60 shore. Does anyone know of a cheap, good backing material that will stick to silicone. I’ve seen people use the spray foam, but that, too, comes off quiet easily. I thought about sandwiching some sort of a mesh during the pouring process to harden. But I don’t think that will work well if i’m trying to create a complex shaped mold. My ideal thought would be to use the silicone w/ a thin layer, then pour something on it that has a strong backing w/out it coming off. don’t mind being permanent.

Any suggestions?

Thanks,

#2

We have a group in here doing some complex silicone bagging. They added various vent/infusion lines in it, by adding bits of some sort of mesh to hold it together. You don’t HAVE to add one piece of mesh. Just small bits overlapping. But you will need at LEAST 2 layers. As for a good backing, add a mesh on the top surface, and add the backing material on top of that. I would think that the mesh would hold down the backing to the part. Try a cloth like mesh, where you have adhesion on both sides of the mesh.

#3

By far most silicone moulds have a hard shell. In the bronze casting business, these are made from gypsum. In NL we have succesfully introduced Acrylic One for that, a reinforced acrylic based material, which can be applied in thin layers, and which does not have the weight of gypsum. (large moulds can weigh a ton in gypsum).

A US equivalent would be “Masterworks”.

#4

Interesting, I’ll look into acrylic layerings. That’s exactly what I’m looking for, a permanent silicone mold hard shell

#5

Here is a picture. There is a thin layer of silicone between the acrylic and product.

From this website:

www.acrylicone.nl

In pure gypsum, it would look something like this:

Imagine the weight, difficulty of handling, etc.

#6

thank you so much for the website. From experience, does this acrylione stick to silicone pretty good or a permanent hardshell? if i use it as a hard shell material, i wouldn’t want it to come off during all the stress in demolding a part from a mold.

#7

It does not stick. The silicone will be held in because of its shape. You would not want it to stick either. Now you can easily remove the hard shell, set it aside, then peel off the silicone sheet, without any need for hammering or forcing.

#8

Another option would be PlastiPaste at smooth-on.com . We use it in combination with brush-on silicones to make glove molds with hard (plastipaste) mothermolds. When you apply your siicone to the plug, add registration keys (glorified bumps in the silicone). This way if your silicone does come out of the mother mold you dont have to worry about re-aligning it for the next part. It being removable is actually very useful.

#9

thanks! I actually tried smooth ons 60A rubber and it works great! I haven’t tried their plastipaste, but I’m in the trial and error phase so thanks for the suggestion.