Smooth on Crystal Clear 202 + mold star 15

[ThatGKchick]

Hello there,

First time boarder here and I just have 1 question for you guys that have experience with this material (It's saturday and I can't call smooth on because they're not open on weekends and I want a quick answer before the weekend ends >_< )

I plan on making a 2 part mold to cast some pieces of a figure I sculpted, some pieces need to be clear resin so I'm going to use Crystal Clear 202 from smooth on, I've gone over all their videos on youtube but they only confused me, on one video they made a 2 part mold using star mold 15 to cast a sea conch shell and just showed how they added the resin to the mold and then popped into the pressure pot for curing, then I see another video showing this product again and degassing the resin in a vacuum chamber and they poured into a *pre heated* mold, so this is the part where I get confused, do you need to pre heat your mold if you're doing pressure casting or not? and if you do need to pre heat it, how do you preheat a mold? I've gone crazy trying to find this info on youtube and google with no luck, I just get results for metal casting :/

I hope someone can help me out with this >_<

ThatGKChick

[RageofAchilles]

hi

Resin curing is an exothermic reaction , the more resin in a curing object will create more heat.
Some clear resins require baking after demoulding to complete the cure, but smooth-on didn't say anything about that with CC 202, so I assume it isn't required.

I assume that smaller items wont create enough heat during curing , so maybe that is why they pre heat the mould. This is easy enough to do in a oven. pre heating isn't normally required for pressure casting, it is probably a requirement of the resin being used.

[Fleafa]

Pre-heating will help smaller items cure, but should also encourage better cross-linking during the reaction, as heat is not lost to the mould. As I understand it, a stronger product should result and, if using clear resin, better optical properties.