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Molds turning blue!

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I have been sealing my PoP molds with Loctite 5 min epoxy cut with denatured alcohol. All seemed to be going well until the last couple of times I've used these molds. The epoxy is turning blue and is flaking off in places. Has anyone else experienced this? I'm guessing it's the type of epoxy and it's inability to handle high heat. It seems to happen when I shoot several times in a row. I am ready to use Devcon 2ton to re-seal but wanted to check here first.

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When I'm making a pop two piece mold, I cook my mold halves for an hour at 170, and then let them sit inside overnight before I seal them.  Pop loves to grow moldy if it still has water in it when you seal it.

I use D2T, thinned after I mix the crap out of it with denatured alcohol, up to 50% for the first coat so it will really soak in.  Then another coat thinned 25%, and I brush the excess out of the cavities so it doesn't pool and lose the details.

I think the 5 minute epoxy may not be soaking into the pop, and that's why it's flaking off.  There might also be some moisture left in the pop that gets trapped under the epoxy, and that might rise up and break the bond of the epoxy.

 

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Before you give up on the mold, try putting them in the oven at 170 for an hour, and see what happens.  If you're lucky, any trapped water will come out, and loosen the epoxy that's left so you can pry it off.  What do you have to lose?  Just go slow.

Remember, the only part you really need to be sharp is the cavities themselves.  The rest can look like crap, just as long as the two faces marry nicely and don't stick together.

When I first started making pop molds, I used yellow carpenter's glue to seal them, and some of my old molds have black mold that grew under the seal coat when they were in the storage cabinet.  If the seal coat fails in places now, I just remove whatever's loose,  reseal with some super glue and keep on pouring.

 

 

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I will attempt to salvage them. The one I'm most concerned about is a rather large mold I used to make some Bulldog style Muskie lures for a friend. It's an open pour mold and I used a soft clay master that no longer exists. It's been with me for several weeks so I'm not sure if cooking it will help. I may have to try and pry away the epoxy (carefully) and reseal. 

 

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5 minute epoxy is a different animal than 30 minute... I'm no chemist, so I can't explain the details.... But I think it's something to do with the different catalysts

As for saving the old mold, I'd probably try covering the old sealer with a few coats of 30 minute.... Worth a shot before you scrap it

Also, since Mark mentioned the moldy problem.. Make sure and store any 2 piece mold open.. If you store it with the 2 halves closed, you could end up with a biology project 

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