Creating a mold using Clay and Foam

[DaftRckr]

Atm, I've been working on a Project I nicknamed "Nothing-M" for a few weeks now and I've gotten my electronics some what down, but I've been trying to figure out a way to create a mold while I have the base shape done with foam and filled with water-base air dry clay. of cousre i know i have to sand it down to smooth it out, but does Anyone know where I need to go from there so i don't mess up the mold i have to make with the build. It's for a clear cast resin mold made of silicone. Thanks

 

[robn1]

I don't have any experience with clear resin, but I know that the original must be smooth and glossy for a clear part. If not the cast will be clouded. Of course it could be polished clear but you may lose detail that way. If you want a frosted/less clear part it's not a concern.

Also some clear resins won't cure properly in tin based silicon, you'll need platinum.

 

[Zlurpo]

The shape and type of mold depend a bit on what the piece will look like. Is it just going to be a tapered cylinder? Do you have pictures of the end goal?

I recommend you use bondo rather than air-based clay. A small can of it will not cost more than $10, and it can be sanded very smooth. After that, you should paint it with a sandable primer, and sand that down with maybe a 600 grit sandpaper, then use an enamel spray paint and wet sand it with 1-2000 grit sandpaper. Then you should polish it using high grit liquid polish and then something like Meguiar's Swirl Remover. Finally, a coat or three of car wax, applied following the instructions on the product.

Basically, the thing has to be as smooth and shiny as a mirror or your clear resin won't turn out well at all.

If you have pictures of the final product (or what it will be) I can give some advice on the shape of the mold and how to make it.

 

[DaftRckr]

my build is simply just a shell like a gauntlet that will have led light strips on the ends to make it glow, here is what im looking to making, im gonna work on a better version later but my first build is of course basic. any of that stuff you guys mentioned can be found at walmart? im working nights and its the only place open when im off. might order my mold from smooth on later for a better mold

 

[robn1]

Yeah the Bondo, primer and sandpaper you can get at Walmart. Looking at the pic of the gauntlet it doesn't need to be crystal clear, a frosted translucent look will light up real nice.

 

[DaftRckr]

Yeah my thought exactly, it actually would help illuminate the build more. Thanks ill post more stuff on it as I go forward

 

[DaftRckr]

I got to get the bondo on and tried sanding it, it looks too bulgy, but it wasn't thought to be easy either

 

[cavx]

Agreed. A frosted part will diffuse the light better.

 

[Zlurpo]

With bondo, you should have a super low grit sandpaper available. Like 36 grit. First, make sure you don't add too much hardener. Then apply it to the piece, and wait next to it. At some point it will get harder and gummy, so it is no longer liquid but it is still pretty soft. At this point you'd be able to easily leave marks in it with your fingernails, Take your 36 grit sandpaper and start shaping it. It will take down high points like a dream. Get the nice general shape you want, and then let it harden more before you move on to higher grits.

And all of the supplies I've mentioned should be available in a WalMart if you go to the right departments. Auto body repair area should have most of it.

 

[swgeek]

If you are working with Bondo you should invest in a surform, you can really save yourself a lot of time and work. If you work the bondo when it's still in the rubbery stage. Also as mentioned earlier, you should decide what resin you will be casting parts with, and find out if you will need a tin based silicone or platinum based.

 

[DaftRckr]

Yeah I got to make the form, need a lot more molding then what I had. I'm gonna order some soon but my mold it dry half way and it wasn't that bad. I know its not perfecr but since its look is more organic, fluid-like really, i figured it wouldnt be so bad. if it comes out too bad im going to re-sand it to a smoother form. it was taken monday

 

[DaftRckr]

Yeah the mold was a bust, I went for a cheap route and got a 25 dollar silicone and wasted it. Bit the bullet and got smooth-on silicone platinum based gallon kit, Gives me a chance to resurface the mold and hopefully learn from the last mold. Also since ive been on night shift i havent had much time on working on it, but i have been working on a few designs for my daft punk/destiny crossover cosplay. Any pointers?