Bubbles

[Laker272]

I have just started pouring this week and have had issues with bubbles appearing in my pour. After I pour they seem to surface a few seconds after I fill the cavity. It is a one piece mold. Am I not heating the plastic enough and air is trapped at the bottom of my mold when pouring or perhaps I am stirring the plastic too quickly? Not sure why, any suggestions?
PS. I sure am relieved there is a site like this with such great support to help a newbie get it right. Thanks

[mrbilky]

Could be your imparting air when agitating your plastic or if you have a POP mold its not sealed enough? Are you stirring after heating?

[Laker272]

I am stirring after heating. The mold is made of plaster and sealed with a water base sealer by Varathane as suggested, a similar product to Spar. I spray a release on the mold after a few uses.

[cdemars316]

I am stirring after heating. The mold is made of plaster and sealed with a water base sealer by Varathane as suggested, a similar product to Spar. I spray a release on the mold after a few uses.


Seal the mold with elmers glue all, pour some glue in a pop bottle and mix it with water till its slightle thicker than milk, flood the cavity and let it sit for 10-15 minutes, empty it out and let it dry, repeat this about 3 times and then put it in the oven on warm or around 150 degrees. this will completely seal the mold. Your bubbles are appearing because your mold is not completely sealed, I have a couple hundred plaster molds and have gone through this multiple times, all it takes is a pin drop that is not sealed and it will draw moisture from the p.o.p. and make bubbles in the plastic.

I use elmers glue because it is a very thin sealant, you lose no detail and get a nice shiny bait, I haven't tried anything else for a couple years because I haven't needed to.

[Laker272]

That is some great info, thank you. Do you think it is too late to treat the mold that I have been using and spraying non-stick spray on. I will sertainly use the glue on all future POP molds. How long should the mold be in the oven for? Also, in your experience is it wiser for me to use the oven while my wife is out?

[cdemars316]

That is some great info, thank you. Do you think it is too late to treat the mold that I have been using and spraying non-stick spray on. I will sertainly use the glue on all future POP molds. How long should the mold be in the oven for? Also, in your experience is it wiser for me to use the oven while my wife is out?

You should be able to treat that mold, unless the previous attempts at sealing it took the detail away, then you might want to make a new one. As far as the oven, I leave them in there for like a 1/2 hour or so, unttil nothing is sticky on the mold and it has a nice shiny finsih. As far as the wife, I would probably do it when she is out, I have been doing this for years so my wife is used to me sticking stuff in the oven, and besides I do all the cooking, but if its "her" oven I wouldn't want to make the boss unhappy. Don't turn it up to high though otherwise it will smell up the house and she will know anyway