Yet another mold box question

[sycor]

I don't I've seen this specific question asked so I figured I would give it a shot.

I know I can use corrugated plastic. I know for small ones I can even try to use lego bricks. Since I don't have either of these, can I use a sheet of hard board? The kind of board that peg board is made of just without the holes. Assuming of course I use the super smooth side for the inside of the box?

 

[Flagg]

I've used pieces of wood screwed together and then I would take some extra clay and run it up the inside seams of where the boards met to make sure it was tight enough to not allow the silicone out. It should work fine for you.

 

[defstartrooper]

Yeah use anything as long as the silicone can't leak out.

 

[sycor]

sweet. I have a lot of hard board. thanks guys!

 

[saxe coburg]

Heck, I've used the card-board box that the 5gal bucket of silicone came in (although I wouldn't roccomend it LOL)... you can really use almost anything as long as you seal it up.

 

[Lightning]

I've used melted wax to coat the inside of a wood mold box. seals it up and makes it easier to pull away when finished.

 

[sapper36]

Don't remember where I saw it but Foamcore works great! Cuts easy - Hot glue it to seal the seams & bob's your uncle!

 

[Rhett J Martin]

Foamcore's the best! Don't cut all the way through, and just bend up the corner, for a leak proof seal. I seal edges with hotglue, and if I have a leak, silly puty works like a charm.

 

[CaptCBoard]

In my experience I've found it to be a good idea to shoot a couple of coats of primer on hardboard (also called Masonite). It is possible for the silicone to react with the hardboard and something leaches into the silicone during the cure. I've had the first pour of resin stick to whatever element of the master was made with hardboard-- in other words the part bonded to the component of the hardboard that had leached into the mold. If you are using hardboard to make mold boxes, this may not be a problem-- other than resin sticking to the outside of the mold.

Scott

 

[exoray]

In my experience I've found it to be a good idea to shoot a couple of coats of primer on hardboard (also called Masonite). It is possible for the silicone to react with the hardboard and something leaches into the silicone during the cure. I've had the first pour of resin stick to whatever element of the master was made with hardboard-- in other words the part bonded to the component of the hardboard that had leached into the mold. If you are using hardboard to make mold boxes, this may not be a problem-- other than resin sticking to the outside of the mold.

I have experienced similar results with hardboard and MDF, especially on cut edges... I have even had the silicone leach into the porse cut ends of MDF and cause issues when trying to demold the box...

But rather then primer I now just lather the MDF up with Vaseline, rub it in with paper towels and then hit the surface of the MDF with a hair dryer and the Vasaline soaks right into the surface of the MDF like a spong giving you built in mold release and once soaked in it hardly has any 'greasy' residue feel... Also if you are using he mold box later as a support mold the Vaseline soacked MDF will also release spilled over resin without much trouble...

If you want to primer it as always I suggest shellac...

 

[sycor]

might be easier to just buy some foam core. Since I don't have any primer at the moment. Thanks for the suggestions.

 

[Sluis Van Shipyards]

Foamcore's the best! Don't cut all the way through, and just bend up the corner, for a leak proof seal. I seal edges with hotglue, and if I have a leak, silly puty works like a charm.

That's what I usually use too. I've only done small molds for models, but it's strong enough to hold up pretty well. I usually just use masking tape to hold all the sides together, inside and out, to seal it.