Question for casters...Shrinking????

[KT EASTMAN]

I seem to remember a time that Resin Casters had to make the molds slightly bigger to make up for shrinkage during curing. Is this really what has to happen if I wanted to say...cast a grille?? Just curious because I do not hear about people oversizing their molds to allow for shrinkage. Any info. would be great!!!! KT

[BigPoppa]

I seem to remember a time that Resin Casters had to make the molds slightly bigger to make up for shrinkage during curing. Is this really what has to happen if I wanted to say...cast a grille?? Just curious because I do not hear about people oversizing their molds to allow for shrinkage. Any info. would be great!!!! KT

I'm not sure how you would make a mold bigger, you would have to somehow enlarge the master. But the faster the resin cures, the more it shrinks.

[Modelmartin]

Modern Urethane resins have almost zero shrinkage. I have measured castings against masters and had to use a caliper to find even a few thousandths shrinkage. I can't vouch for some of the cheezy resins out there, though.