The instructions on this particular urethane resin says demold in 90 minutes. Maybe on paper that might be true. After making quite a few figures using this urethane, that it is still too soft. This chest canopy is really incredibly small. Yet at 4 1/2 hours it is just acceptable for me to consider demolding it. Otherwise I will have to hang it. Because if I put it down anywhere, it will develop a flat spot. It could also sag if hung. I find the magic number to safely remove from the mold using this urethane resin is 6 hours. But 4 and 1/2 hours seems to be okay for these chest canopy's.
I remember the first clear magno heads I made. I was so impressed with myself because it looked really good. So I took it out of the mold and put it safely down. Went to look at it a few hours later and there was a huge flat spot on the back of the head from where it had been resting.
On a side note, I have started trimming up the boots. Taking off the flash, trimming up the lines and drilling the boots for a 5 mm stand. Sorry I am not providing a stand, but I am sure most people have at least 1 from the Palisades line. I should have the boots done by monday. Then I will do the thighs and torso's. I could quite possibly have all the legs done and riveted by next weekend. Then comes drilling out the chest piece. Head, 2 arms, torso and back. 5 holes have to be drilled in it. 5 MM. I do these all by hand. I start with a small drill and work my way up. It takes longer, but its more accurate. If I accidentally am off center I have several drill bit sizes I can still go through to bring it back inline. Oh yeah...several weeks worth of work yet. Easily.
If you leave it in too long do you have to worry about damage to the mold from heat released by the resin?
ReplyDeleteAny heat generated happens with the initial mixing of the resin. Any heat created has already dissipated by demold time. So leaving it a little longer in the mold doesn't hurt it a bit.
ReplyDeleteAlso, because the pieces we are casting are pretty small, there is actually very little damage done to the mold because of heat.
One of the problems I had after multiple pulls was the RTV would stick to the resin in spots and tear away from the mold when I'd pull the parts out. Usually it'd happen after around 25 pulls. It seemed like it'd happen regardless of using mold release or not. I wondered if that was mold degradation because of age or heat or I left the part in too long or whatever.
ReplyDeleteBased on what I have been seeing myself, and I don't use mold release, is that it is mold degradation. Is it caused by the heat generated??? I am going to say no. And only because the piece I am making is very small. And my answer only reflects the Chest Canopy I am doing.
ReplyDeleteThere isn't enough heat generated to do that with this mold. It might have some effect on a larger mold where substantial resin amounts are being used and the heat generated is much more substantial.
Otherwise my results aren't much different than yours. I get about 25 pulls myself before the molds crap out. Maybe a few more for simpler molds.