resin casting in an ultracal 30 mold

[Moviepropmaker6]

Hey,

just wanted to ask you guys if it is possible to cast epoxy resin an ultracal 30 mold.I've seen a youtube video where a person used fibreglass cloth and fibreglass resin to make a mask in a plaster mold,does the same go with epoxy resin.

 

[robn1]

Yes it will work but there are some issues to address first. Plaster/Ultracal is porous and needs to be sealed; Smooth-On and other casting suppliers make a spray sealer for this purpose or you can use paint. You'll have to use mold release so the casting won't bond to the mold, either spray release or paste wax. But most importantly to master part must have a low draft design, meaning it can't have any protruding shapes that will lock it into the mold. The original master must be removable once the Ultracal sets, likewise for the epoxy casting.

 

[Moviepropmaker6]

Yes it will work but there are some issues to address first. Plaster/Ultracal is porous and needs to be sealed; Smooth-On and other casting suppliers make a spray sealer for this purpose or you can use paint. You'll have to use mold release so the casting won't bond to the mold, either spray release or paste wax. But most importantly to master part must have a low draft design, meaning it can't have any protruding shapes that will lock it into the mold. The original master must be removable once the Ultracal sets, likewise for the epoxy casting.

Thanks for the reply,i really needed some help with this.

 

[rbeach84]

Looking at an injection molded kit's parts will show some of what Robn1 was speaking of since rigid steel molds are used for IM kits. 'Draft' is that little bit of angle incorporated in a part to ensure the molded bits release properly (think of how a frozen popcicle or ice-cube trays are made - they have 'draft' in them too...) Essentially, the molded part must have an unobstructed path of extraction from the mold, which is obviously the same vector for all points of the molded part. Making the mold in multiple parts (like two halves) that can be separated after the part is molded also allows for greater shape options. Also consider whether the original 'master' part should be broken down into more parts to simplify the mold engineering. Not a big deal, just remember to provide for some way to 'key' the separate parts for smooth, accurate assembly.

Cheers!
Robert

 

[Moviepropmaker6]

Looking at an injection molded kit's parts will show some of what Robn1 was speaking of since rigid steel molds are used for IM kits. 'Draft' is that little bit of angle incorporated in a part to ensure the molded bits release properly (think of how a frozen popcicle or ice-cube trays are made - they have 'draft' in them too...) Essentially, the molded part must have an unobstructed path of extraction from the mold, which is obviously the same vector for all points of the molded part. Making the mold in multiple parts (like two halves) that can be separated after the part is molded also allows for greater shape options. Also consider whether the original 'master' part should be broken down into more parts to simplify the mold engineering. Not a big deal, just remember to provide for some way to 'key' the separate parts for smooth, accurate assembly.

Cheers!
Robert

thanks, the plaster mold i'm using is an open mold its not a two part mold.again thanks alot