Molding Question

[psytce]

Hello,

I would like to try and create a mold of a large part and would like to try and make a mold that has a layer of molding rubber and then a hard outside. I had thought I saw this done somewhere but I can't find it. I would like to do it this way for 2 reasons.

1 - I wouldn't use as much rubber
2 - I think it would last longer because of the hard outside.

This is for a 2 part cast so I would have to do 1 side and then the other.

I was thinking I could do a brush job on the piece, and after a few coats use some gauge (bandage) to give it some strength. Then I would need to add the hard outside case, this is where I get lost because I'm not sure what I could use.
After creating the "Top" side I would then turn it over to create the bottom.

I was also thinking about adding a lip around the outside so I could use clamps to keep the 2 pieces together.

Does anybody have any ideas that could help me do this......

Thanks,
Tommy

[Johnnycrash]

What you are looking to do is create a "mother mold". That is the rigid shell that holds the shape of a thinner, flexable mold, most oftern of latex. But it works with silicone, and urethane as well.

Do a google search, and you will find a wealth of info. BTW, do NOT add any material to the mold itself for strength. You want the mold to maintain it's flexability. The mother mold will give it it's strength.

In one technique, you cover the master with a layer of clay, as thick as you want/need your mold to be. Then you create the mother mold, usaually of fiberglass. Once the mother mold is set, you remove it, and the clay, and re-install the mother mold. Then you pour your rubber between the mother mold and the master, making a perfect fit. This also means you can have a much more complicated mold shape, as you do not need to worry about the rubber (silicone) flowing off the master. Otherwise, you would need to make the silicone mold with a thixotropic silicone mix. And that creats problems all it's own.

Good luck.

[modeler1964]

Try either of these two companies:
Smooth On or TAP Plastics
Both sites have tutorials on brush on molds with plaster mother molds as you described. I am going to do the same thing and buy smooth on's product called "Dragonskin".

[psytce]

Thanks for the help. I'm going to try both latex and omoo30 on something to see which I like better.

Tommy

[chen18]

(laugh)the more reasons shall be made of good discission that we can follow or making a point what is in there!!therefore your idea will be mate as your thinking..


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Micro molding