THO Game Calls Forums
The Art of Handcrafting Custom Game Calls => Molding Calls, Guts, Inserts & Other Parts => Topic started by: Roger Smith on May 30, 2014, 10:23:31 PM
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First, I watch some youtube vids of molding by Curtis.
I just started trying to mold some duck call barrels. I use a piece of 1.5 inch pcv pipe. I placed several small pieces of wood in the pipe. I mixed the alumilite, added the green color and poured into the mold. I set the mold into a pressure chamber and put 50-55 PSI for 30 minutes.
As you see in the image, there are small air bubbles in the area close to the wood. There is also one void that may not show up in the image.
(http://i1278.photobucket.com/albums/y509/Overtrim/IMG_0191_zpsa8923022.jpg) (http://s1278.photobucket.com/user/Overtrim/media/IMG_0191_zpsa8923022.jpg.html)
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I don't have any answers, but ask this guy https://www.facebook.com/pages/Southern-Flight-Lanyards-Southern-Flight-Calls/526903447388179 He pours his own stuff with Alumilite so he might be able help you out.
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I think you need to keep the resin under pressure for a longer period of time. Best I can remember it is recommended to keep the pressure on for at least 2 or 3 hours, but from the IAP some did it longer. The resin may look and feel solid, but the fully cure time is around 72 hours. That air bubble is kept small as long as there is pressure on it. If the resin hasn't set hard enough and you release the pressure the air bubble can or will expand.
Don't take this to the bank, it has been a few years since I quit playing with resins. All of this info is off my own memory bank.
Marvin
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Also how dry was your wood? With aluminite moisture is a big concern. Any moisture in the wood would react with the resin!
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I think you need to keep the resin under pressure for a longer period of time. Best I can remember it is recommended to keep the pressure on for at least 2 or 3 hours, but from the IAP some did it longer.
Marvin
Marvin, I believe your right about it needing to be under pressure longer. I was talking to a guy a while back that said he has his under 50-60 PSI for about an hour and a half to two hours. Barry, good point about the moisture, I've read about the moisture causing the alumilite to react when its not low enough somewhere on facebook.
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Also how dry was your wood? With aluminite moisture is a big concern. Any moisture in the wood would react with the resin!
Barry, I would have considered it dry. The wood was small pieces of Australian Burl scraps that had been laying in a box for 2-3 years. You are correct about moisture. I tried one pour that had 2 drops of a tint that was water base and the pour foamed like crazy. It looked like a sponge.
I went back and Watch the vids by Curtis from TurnTex and he was stating 20-30 minutes under pressure. I will try it under pressure longer the next time.
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If you want to play with the resins I recommend spending a few days reading the casting threads on IAP. The penturners have been working with Alumilite and Simlar41 for years before the callmakers. They have already sorted out what works and what doesn't work. There is no point in trying to reinvent the wheel, when they have done it and moved on up to the fancy chrome rims, and went on past to better things.
One thing to remember, the Shore factor of the resins is not the same as the Shore factor of the cast acrylic from Delvies. Some of the end products will not work as good as the real acrylics.
Marvin
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Your problem is absolutely moisture in the wood. Keeping it in the pressure post longer will not help this at all. I typically only leave stuff in the pot for 30-40 minutes unless it is real cold in my shop. Then I go one hour. The only time I see things like this is when I try to take a short cut and the wood is not REAL dry. My suggestion is to put your wood in a toaster oven at 200° f for a few hours, then cast it while it is still warm. That will solve this problem for sure.
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Your problem is absolutely moisture in the wood. Keeping it in the pressure post longer will not help this at all. I typically only leave stuff in the pot for 30-40 minutes unless it is real cold in my shop. Then I go one hour. The only time I see things like this is when I try to take a short cut and the wood is not REAL dry. My suggestion is to put your wood in a toaster oven at 200° f for a few hours, then cast it while it is still warm. That will solve this problem for sure.
Curtis, thanks.
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I don't have any answers, but ask this guy https://www.facebook.com/pages/Southern-Flight-Lanyards-Southern-Flight-Calls/526903447388179 He pours his own stuff with Alumilite so he might be able help you out.
This guy will help you out. His name is Brannon Gragg. Great guy.