I am new to resin casting and am currently making a burl and resin cast.
The form is a 4x4x4 cube that will have 4 pieces of burl in it. Once cured the plan was to cut the block of resin into 4 pieces and then turn each piece.
Since it needs approx 35 oz (64 cubic inches converts to approximately 35 oz but I’ll be using 32oz I think due to the displacement if the wood) my question is pouring that much mixed Clear Slow at once going to be problematic? (I am using a pressure pot BTW)
I've done a bunch of 4x4x4 cubes with alumilite clear slow. I did have issues with the regular clear, but the slow didn't overheat. Do we careful with the burl and ensure it is very dry. My hybrid stuff tends to fail because of moisture. I'll usually put the wood in the toaster for a few hours before the pour and put into the mold shortly after removing. If you haven't tested with the wood before, I'd try a smaller pour first so you don't waste your materials. Good luck!
So it worked out pretty good. But I got some weird “bubbles” on the surface of the burls that I am not sure how they happened. Only three of the four had them too which was odd. And the casting itself was crystal clear Which I was very happy about.
Some will tell you those bubbles are caused by moisture in the wood. I disagree. When you have moisture present, even small amounts, clear slow will foam and you'll have an unusable casting.
I've seen these bubbles in my castings. IMO, they are mainly related to how much entrained air is in the resin after mixing. A pressure pot doesn't get rid of the air, it collapses tiny bubbles. If enough bubbles merge they form larger bubbles that don't collapse at 50 psi. This effect seems to be amplified by higher curing temps, but I can't say for sure.
I manage the problem by trying to keep the resin as free of air as I can while mixing and pouring. Stir slowly, keeping your stick in contact with the bottom of the container. When pouring don't let the resin "fall" into the mold, pour down your stir stick and let it flow into the mold.
I also don't cast if ambient temps are over 85 F. The efficacy of this is not estabished. Lol. I must have a hundred experiments littering my workbench.
Not to answer your question...but since I am fairly new to casting I usually use too much resin. Sooooo I keep several pieces of various sizes of PVC pipe on hand and plug one end. If I have enough extra I pour it into the pipe. When cured it pops right out and I use the extra for all kinds of things to enhance my art. I most always turn the pieces on my lathe. They come in handy for me lots of times. Enjoy making!!