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basskat

First Time Problem

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Maybe some of you guys have had this problem. I completed a new mold, it's made from Durham's. I baked the mold and covered it with Devcon. Tonight when I would pour air bubbles would come through my plastic and bubble up. Any idea what's causing this? I sure hate to trash this mold since it has a lot of small detail work and was a pain to make.

I've got 50 molds made from plaster and Durham's. None have ever reacted this way.

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Something you might want to try - Pour a bait, pull it out once cooled, pour a bait in the same cavity with a sample of clear plastic (no additives).

Note where the bubbles originate.

If the bubbles are rising from pores in the epoxy (just about impossible), that may be the source. If the bubbles are originating in the plastic, moisture in the plastic causes bubbles, though usually only in the pyrex when first heated. Low humidity is the best. Is the room 65 or above? Pouring in a cold garage might contribute (doubt it though).

Sam

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Are you sure the cavity is completely covered with devcon? If you missed a spot you could be getting air from this spot. Also, did you cure your mold sufficiently in the oven? Moisture will find a way out - just like on a house that is painted. If there is moisture in the wood - it will work out and cause the paint to blister. Good Luck!

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I wonder if a cold garage is the culprit. I just started having that problem too. My garage is a little on the cold side. All I have is a small heater pointed at my work bench. I guess it could be the molds. It happens to me when I pour in the water putty molds. :?:

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I have had this exact problem...there were gaps in where I thought I had completely devconed the mold.

Kidlizard gave me a valuable tip when I was having this problem. Add some food coloring (just a little red or something) to your devcon. After coating, you can tell instantly which areas have been covered good or not.

I can promise you I thought I was giving these molds a great coating however found that after adding the food coloring and then coating..areas that looked coated to me, where not coated well enough.

Also, if you are not getting bubbles when using your other molds with the same plastic, additives etc. then there is no way it could be related to those items. I do get bubbles from the humidity and cold but they are in the plastic when I heat it, not originating from when I pour the mold.

Just my 2 cents!!

Jim

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