Molding a small part with intricate detail

[Maelstrom]

No undercuts or anything. Its an MQ casio calculator keypad. Boba guys will know. I've tried a couple of times and am having no luck getting a bubble free detail in the mold. I don't have the kind of room for a paintpot/compressor much less a dagassing chamber so my question is...

Since RTV Silicone will bond to itself even when cured pieces are mixed with new would it work to brush on a layer of the silicone 1st, let that cure and then pour the majority of the mold afterwords?

Anyone ever tried this? I know it would be a little more time consuming vs. the degassing, but like I said...:unsure

 

[adamata]

Yup, that should work. I know with the stuff I use, it does. apply a layer with a brush and make sure you get all the touch spots. then, add the rest.

 

[Maelstrom]

Thanks! I really thought there was no reason this shouldn't work, but wanted to see if anybody had tested those waters as I would probably have shoved a railroad spike through my head if I went through this again with another epic fail.

Sometimes I hate mixing silicone. Great hobby to pick, huh?

 

[robstyle]

Since its such a small part to mold, why chance it with a brush up attempt and then put the mold back on? If you have an air compressor, you can lightly blow air into the silicone knocking any bubble loose. Most people pour silicone from a height in a thin stream to help alleviate bubbles. It never hurts to brush the silicone over the part since youve got a good working time with the stuff.

If the part yourt trying to mold is the same seen here, Ive molded the exact part your trying to make and never had an issue. These were strait up pours with a little powder in the mold. Your casting material will also be crucial. I love to use a mild plastic thats super fine and isnt brittle like cheap resin.

 

[Maelstrom]

Well usually when I mix I let it sit for a bit so that some of the bubbles will rise to the top on their own. Then pour from a height in a thin stream and not directly on the part so to let the silicone flow over and pick up the detail. Where I was getting the problem was around the buttons. One of them (different ones each time) would trap a bubble.

I'm trying to get the best mold possible because I would like to try casting one in metal.

 

[VashDstampede]

If you have an airbrush, apply a thin layer of silicone first, then blow air so that the silicone would go into all the details and pop any bubbles that get trapped.
Thinning the silicone a bit will also help in being able to get a good first coat. Then pour another thicker layer of silicone.

 

[vistaVision]

I love to use a mild plastic thats super fine and isnt brittle like cheap resin.

I'd be interested in a specific material recommendation that has worked well for you.

Thanks!

Marcus

 

[Maelstrom]

If you have an airbrush, apply a thin layer of silicone first, then blow air so that the silicone would go into all the details and pop any bubbles that get trapped.
Thinning the silicone a bit will also help in being able to get a good first coat. Then pour another thicker layer of silicone.

You mean brush on a thin layer then blow it with the airbrush, right? Not lay the thin layer on with the airbrush, right?

Is that possible? Never heard of that as a technique before.

 

[VashDstampede]

You mean brush on a thin layer then blow it with the airbrush, right? Not lay the thin layer on with the airbrush, right?

Is that possible? Never heard of that as a technique before.

Yeah, the silicone never touches the airbrush, it is just used to push the silicone in the crevices and pop any hidden air bubbles.

Certain silicone can be airbrushed just very thinned out. That's how they paint silicone masks with tinted silicone. However, for molding, I don't recommend it

 

[ArtisanProps]

Actually using a brush is pretty effective by itself.. I used that technique for
years until I bought some machines to help me.. Just make sure the brush you
buy doesn't loose hairs easily, other then that like everyone else said, just brush
on a thin layer, let it set, mix up some more silicone and pour your mold......

I've tried the air compressor method but wasn't fond of it myself, but give both
methods a go, and see which one you like better