Crystal Clear 202 Casting Thickness?

[throw]

Hi all,

I'm casting with crystal clear 200, and for health reasons I am casting outside. Temperature varies over the cure time (16 hours) so I'm looking into crystal clear 202, which has a nice and short 90' cure time.

However, my objects have a thickness of 3cm at their thickest point. I'm very concerned about safety: I'm already wearing organic vapor masks and coveralls/gloves outdoors, and not willing to post cure these objects in my kitchen. I'm just demolding into tupperware and waiting a loong time.

Does anyone have experience casting with 202 at thicknesses greater than the maximum? (1.27cm). I heard the resin can actually smoke (and potentially discolor), which is a situation I really don't want.

Clarity, surface detail and hardness are all important. No easy task.

I'm using a silicone mold, which I have been heating to 60˚C before casting. No vacuum. Also using a .001 gram scale, but it self calibrates and is not for dynamic weighing (which I am doing anyway) so it's probably not as accurate as it's designed to be. Any advice is appreciated. Safety first, results second!

My backup plan is to find an autoclave somewhere that I can use.

Thank you. Nice forum btw.

[mangozac]

Hi Throw, welcome to RA!

Really, you'd be best asking these questions of the people at Smooth-On - it's their product!

So I'm referring to the Smooth On site here:

Firstly, it sounds like your adherence to safety first is warranted with this stuff. They are warning that it is quite a nasty irritant! I wouldn't want to post cure in my kitchen oven either!

They say that the CC220 product must be post cured, but the TDS also recommends post-curing for thin pieces on the rest of the Clear Cast range. How much of your part is greater than the maximum 1/2" thickness recommended for the 202? Ultimately I'd say the best solution would probably be to buy a cheap benchtop oven and set it up for post curing, then use the Clear Cast 200.

I'm sure your scales will be fine. Absolute accuracy isn't really important as much as repeatability and relative accuracy are.

[throw]

Hi, thanks very much for your detailed response!

I’ve called Smooth-On before to get safety equipment recommendations. I didn’t call for the 202 question because I figured they wouldn’t deviate from their printed information. But it’s a good suggestion and I will do it, just in case

I did a test cast of the 202, which I didn’t mix properly (a little too much hardener). I think once I get the mixture right it will be okay, the mold seems completely fine. The objects are no wider than 4.5cm at the widest point, ~2cm high, and 3cm thick all the way through. So it’s a small object but is twice the recommended max thickness.

I’ll search the forum for discussions on benchtop ovens. Something small and cheap would be perfect.

Thanks again for all the advice, if I have success with it I will report back.

[mangozac]

[throw]

I just wanted to follow up in case anyone finds it useful. Smooth-On confirmed on the phone that the size I am casting is not dangerous. I'm still mastering the recipe for my cast, but the advice about the oven has been super helpful. I appreciate you leading such a helpful and good forum! Thanks again

[mangozac]

Great to hear. We appreciate the follow up!