Is Amazing Clear Cast compatible with molds made from High Strength 3?
I've been having an issue lately and I've been trying to figure out what the issue is. A few months ago I bought High Strength 3 from Amazon and had great results using it with Amazing Clear Cast resin. Unfortunately those molds are now breaking down because I've used them so much, so I purchased High Strength 3 and High Strength 2 directly from Alumilite but I've had bad luck with them now. All of my casts keep sticking to the silicone and I've been trying to figure out why. Thought that maybe my ratios were off because I'm using a different scale than I did the first time, so I tried mixing it with a 4:1 volume instead but still I'm having the same results. The resin sticks to the silicone and I have to cut them out of the mold... which of course defeats the purpose of re-using the molds. Also, the High Strength 2 seems to be worse about sticking. Unsure why, but I suspect it may have been bad because there was dried crusty material at the bottom of the base container. The catalyst also had floating particles in it when I shook it prior to use. Is that normal or was it also bad? I've run out of both of my 1 lb kits trying to figure out what is going wrong this time vs my first successful attempt. Wanting to buy more but hesitant since I can't seem to reproduce my first successful results.
That sounds like a bad batch, I've had a few batches directly (very recently too) from Alumilite and had no problems. Are you still using Clear Cast resin? I've found that the Clear resins always come out a bit sticky when I demold after 24 hours. Have you been warming the molds up before casting? Have you tried using a release agent in the molds? Both of these help with demolding. Also have you left the new molds alone for a couple days after the pour? They usually do best when they've either had a few days to cure all the way through or have gone through a "post-curing". I know that I have a bit of trouble with freshly made molds if I don't do a post-cure or don't give them a couple days to just sit. Another thing is the resin might need warming too, sometimes it can get moisture contamination (by leaving it open too long or the caps aren't tight when you close them or even if you've had them for a while) which is hard to get rid of but resin can still be used with a few fixes - let me know if you'd like to know those.
Also you said you're doing the molds by volume but using a scale? Both HS-2 and HS-3 are measured by weight - volume doesn't work as well and I know that from experience. I noticed a big difference when I bought my scale and made sure to measure it by weight. The Clear Cast is done by volume but not weight.
I normally cast with RC-2 and cast very small items (smallest was 1/2" tall x 1/2" wide x 1/4" deep) so warming the mold is a great help. When I use Clear Cast, the casting comes out better when I warm the mold first then leave it alone for a couple days (in the mold) before demolding. Heat helps a lot with the cure, if you have an old griddle you don't use for food (and be sure to not use it for food afterwards) you can use that to heat up the mold while the resin is in it. I've got instructions on how to do that if you need them.
Give them a call and let them know you got a bad batch, they'll get you fixed up right. Be warned that they're in the middle of a transition (I believe they're expanding) so it might take a second try to get someone on the phone but it's well worth the effort and patience.
Thank you! I think my problem was that I wasn't letting the molds cure long enough before pouring resin (I'm sure the bad batch didn't help either).
Also, to clarify, I used most of both High Strength 2 & 3 using a scale to measure by weight, and then thought perhaps my issue was that my scale wasn't calibrated properly (it was a gift from someone who hadn't used it in a long time) so I tried doing it by volume instead, which still didn't work. But, I also haven't been letting it cure long enough, it seems. I'll probably just find a way to efficiently use the entire kit at once until I can find (and afford) a reliable scale. I've been measuring my resin by volume, and have never had issues with it. I also cast small items, probably about the same size as your smallest, and usually I can take them out of the mold within 12-24 hours. But, speeding up the cure time would still be lovely and I would love for you to share your instructions on using a griddle to heat up the molds.
I will definitely give Alumilite a call about my bad batch. Thank you again!
There's three ways to warm a mold: #1 Warm the mold in a conventional oven at 120-150° for 15 minutes #2 warm your mold in a microwave for 1 minute/lb of rubber on high #3 Use a mold only griddle
For the griddle, spray the griddle with the UMR release prior to setting the mold or resin on it. This makes an easier clean up as things can get over poured. Then put the mold on there to preheat it and you can let the resin sit on there to keep it warmed (not the resin in the bottles, the mixed resin in the mold) at about 120F so the reaction time to cure in the molds is short and you can even leave it right in the mold while it is curing, right up to the demolding process.
Also I got my Taylor kitchen scale at Walmart for like $12-20. There's even a trick to recalibrating it too which I can share if anyone needs it.