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Old 04-27-2018, 07:53 AM   #1 (permalink)
 
Join Date: Oct 2016
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Default need some help

I have started casting my own blanks. I purchased some Alumilite clear. So far I have cast about a dozen blanks. My pressure pot is setup to run at 40 psi and I leave it running for about 75 minutes. Then I release the pressure and let the cast sit overnight.
The work is being done in my basement workshop where the temperature is around 60 degrees. I bring the mold upstairs to room temperature for the overnight time.
Here's the problem: Bubbles. Sometimes lots of bubbles; sometimes only a few. I'm also have difficulty getting the resin into all the void areas when casting with wood.
Is the temperature I'm working at too cold? Why do so many bubbles show up when the pressure is at 40 psi?
Any thoughts and comments will be appreciated.
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Old 04-27-2018, 09:08 AM   #2 (permalink)
 
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Are you warming up the molds before casting?
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Old 04-27-2018, 09:40 AM   #3 (permalink)
 
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40psi should be plenty to avoid bubbles.. Assuming the resin isn't already too far cured by the time you get it into the pot. Are you getting these even if you have just straight alumilite?
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Old 04-27-2018, 10:50 AM   #4 (permalink)
 
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You might try leaving the pressure on overnight . If it is released too soon , the bubbles will be there . Your cool conditions probably slow the cure process .
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Old 04-27-2018, 12:07 PM   #5 (permalink)
 
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Which is better for casting: a pressure pot or a vacuum pot?
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Old 04-27-2018, 01:46 PM   #6 (permalink)
 
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Quote:
Originally Posted by CabinetMaker View Post
Which is better for casting: a pressure pot or a vacuum pot?
Always use pressure castin. never vac.
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Old 04-29-2018, 08:05 PM   #7 (permalink)
 
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My thought is that it could be air or moisture. As mentioned before are you warming the mold and resin? My process is that I'll take the mold with the tube or other materials that I'm wanting to cast and put them in the oven anywhere from 15 min to 45 min. I'll also warm the resin. Not to get it hot but to help it flow. When I feel comfortable that the mold and it's contents are warm and moisture free I'll mix the resin with the hardener and pour quickly in the mold. I've found trying to play with or fish out the bubbles just wastes time. It's better to let the pressure pot take care of that. I let Alumilite stay under pressure for at least 2 hours. If you release the pressure too soon and the resins still soft the bubbles will expand causing failure.
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Old 05-12-2018, 01:21 PM   #8 (permalink)
 
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Quote:
Originally Posted by Kenny Durrant View Post
My thought is that it could be air or moisture. As mentioned before are you warming the mold and resin? My process is that I'll take the mold with the tube or other materials that I'm wanting to cast and put them in the oven anywhere from 15 min to 45 min. I'll also warm the resin. Not to get it hot but to help it flow. When I feel comfortable that the mold and it's contents are warm and moisture free I'll mix the resin with the hardener and pour quickly in the mold. I've found trying to play with or fish out the bubbles just wastes time. It's better to let the pressure pot take care of that. I let Alumilite stay under pressure for at least 2 hours. If you release the pressure too soon and the resins still soft the bubbles will expand causing failure.
Going through the forums before I start casting....
How do you "warm" the mold and resin? What do you put the resin in to warm it? Do you put the bottle in hot water? How hot is the oven when you warm the mold? Mine are HDPE molds.

Why not keep the pot pressurized overnight while it cures?

I've read that I should wait until the alumilite stars to thicken before adding accent swirls etc?
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Old 05-12-2018, 02:05 PM   #9 (permalink)
 
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I place my molds in the tank and place a clamp light over it. I also put my cups of resin under a light for about 20 minutes. You’ll know if it’s thin when you stir it. Just don’t get it too hot or it will cure too quickly. Leave the pressure in the tank. Releasing it before the resin cures will only allow the air to be visible.
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Old 05-12-2018, 03:29 PM   #10 (permalink)
 
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Quote:
Originally Posted by JohnU View Post
I place my molds in the tank and place a clamp light over it. I also put my cups of resin under a light for about 20 minutes. Youíll know if itís thin when you stir it. Just donít get it too hot or it will cure too quickly. Leave the pressure in the tank. Releasing it before the resin cures will only allow the air to be visible.
Excellent! Thanks.
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