Any issues baking Smooth-Cast 300?

[Davehal9000]

I am restoring an old training anti-tank mine. Don't worry, it was never a live piece of ordnance!

Decided to use Smooth-Cast 300 but didn't want it to be permanent. I created an internal mold in the mine, poured in OOMOO 30, making a male master, then used the same to make a female mold to pour the resin. Turned out fine.



The other half, not so much. Am trying to cast the void shown in an orange resin. Shrinkage between the male mold and the body leaves a lot of fine tuning to make everything fit. Getting everything into place is tricky.



Am debating using Sculpey III oven baked clay to fill in the void, make it pretty, and baking it all while assembled. Concerns are messing up the resin (I can pour identical replacements) and messing up the original paint on the mine. Baking temp is 275 F.

Any suggestions?

 

[cavx]

If in doubt, test first. Maybe don't bake as hot and just bake longer.
I don't know the conversion from F to C but most post curing of resin can be as hot as 80 degrees C for upto 6 hours.

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[bookface]

Your smooth cast resin will go soft at that temp, at the very least. It doesn't look like it would be subject to much deformation, but it could have other side effects. I would ask smooth on, and if they don't say no, then do a test piece. Instead of sculpey, what about the smooth on free form air? Or even bondo? Add it to one of the pieces and then sand to fit.

 

[Davehal9000]

My intent is to cast everything in the final colors. Don't know that I can do that with bondo.

Final product will have a texture to it. I glued sandpaper to the male masters to make the molds.

May have to end up casting it all as one piece and painting the orange section

 

[cavx]

Is it meant to come apart? If not then sounds like your plan B will be easier.

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[Davehal9000]

Not intended to come apart but don't want to ruin the piece by filling it with resin and having to grind it out of it doesn't turn out righy

 

[Davehal9000]

How durable are air drying clays?

I don't intend this to be handled much but am concerned handling might ruin the texture or heat and humidity may warp or melt it

 

[bookface]

Not sure on durability but you can expect significant shrinkage on air drying clay. I think paint will be your solution on this piece, whether you do it as one piece or fill the gaps with something and paint the second piece.

 

[cavx]

Not intended to come apart but don't want to ruin the piece by filling it with resin and having to grind it out of it doesn't turn out righy

Can you make a mold and cast the orange part first? Once cured, can it be embed into the other part later?

I have done separate pours of parts into a mold without a release agent and they tend to fuse really well. I have also used release and been able to separate the parts later. It might be a bit harder with hard setting resin. I was using flexible at the time.

 

[Davehal9000]

I made a male master of that entire section and used it to cast a male copy. I cut out the orange section out and made a mold for the yellow.

In theory I could take a casting of the entire section, cut out the yellow section and have the orange section I need. Shrinkage is the problem I'm having.

I Crack out the Dremel and end up removing too much. Plus it's like capping a tooth through the rectum trying to get it in place.