I have a question related to casting a pine cone in the Slow resin. I have attempted this twice and in both cases, several cracks radiate out from a few of the pine cone points. Pine cones have been dried and stabilized using cactus juice. Alumilite was cast in a pressure pot at 55 psi.
Casting is otherwise clear, no discoloration or cloudiness. Total volume of resin was about 2 cups.
1: Yes, exact ratios by weight, using digital scales with +/- .2 grams accuracy. Mixed very well, about 3 minutes, no trails and very clear before pouring. 2: Pine cone is about 4" tall and about 2" wide at its widest point. Single pour in a cup. Cracks radiate out from some of the cone points that are about .5" from edge of the pour. 3: Probably a day between stabilizing and the resin pour. 4: CJ was oven cured at 200F for a couple of hours then placed in a ziplock bag until I was ready to use it.
So, could this be an exotherm crack? Too much for a single pour? If I recall, I had about 200 grams of A and the same for B.
You shouldn't be having exotherm cracks at that volume. I've done pours of 900 grams without issue. Alumilite's website claims that pours over 160 oz. (4,480 grams) can cause exo cracking in the Clear, I'm assuming that holds true for the Clear Slow as well.
I know nothing about stabilization with cactus juice or it's effects on Clear Slow. I don't stabilize any of the wood I embed. Instead, I seal the wood with polyurethane and give it a few days to cure before casting. So far that's working for me.
I don't work a lot with the Clears on wood so I'm going by what I've learned from others. Lawnboy is right, sealing the wood is usually what I've seen done instead of stabilizing it (I'm sorry I didn't remember that right off the top of my head) and it has a better outcome on wood.
Everything sounds like you did it like I do for my regular castings aside from stabilizing with cactus juice. Any moisture will usually cause resin to bubble up or not set properly so I'm thinking that the cactus juice might be part of the problem. You've already put some work and money into the project so let's see what we can do to fix it for you.
Since these are pine cones, I'd say try brushing on a sealer over and into the cracks and let it dry completely. Then add some more Clear over top of the cracks and fill them in with it - use a brush if possible as it should get the Clear into the cracks better. This *should* work but I haven't got first hand experience with it on wood - just on filling cracks and voids in resin. Try this and let us know if it works for you.