squigster Posted March 2, 2009 Report Share Posted March 2, 2009 I heated 4 oz of plastic in two seperate Pyrex cups today and was trying to do laminates, I poured the bottom of the 6 worms by transferring some plastic from the 1 pyrex into a 1/2 cup aluminum measuring cup and pouring the bottom of the laminates. I then transferred the top color plastic to another 1/2 cup aluminum measuring cup and poured the top half. The baits look good except I got cold cracks. I am using POP as the mold. Can I preheat POP to try and compensate for this or will it crack it? Also, how do you keep your plastic hot enough in between pours if you are using the microwave? I tried two Pyrex cups in the nuker together today (same size Pyrex with same ingredients except color) and one heated up significantly faster than the other. Any explanation for this? I tried putting the aluminum cups on a hot plate but the plastic started to scorch. I am obviously having a hard time managing this in a 43 degree garage. Any suggestions or help would be appreciated. Quote Link to comment Share on other sites More sharing options...
Zbass Posted March 2, 2009 Report Share Posted March 2, 2009 You can preheat the molds. POP will hold heat for a little while. Some people do this by pouring a batch of plastic through the mold before you are ready to pour your multi color. Also, on a multi color pour, unless you have your mold very warm, you hould only do one worm at a time and then the next worm. pour your first color in one cavity and then the second color. Then move on to your second cavity. Hope that helps. Z Quote Link to comment Share on other sites More sharing options...
Vodkaman Posted March 2, 2009 Report Share Posted March 2, 2009 (edited) My concern is, that if you seal your PoP mold all over, as I do, then heat the mold, that blistering could occur. PoP molds are full of air which expands upon heating. If you only seal the working cavity, then all should be well. I would like to hear from an experienced PoP mold builder to confirm or deny this though. I could be way off on this idea, as the hot plastic would have the same effect as pre-heating. Secondly, aluminium cups are probably the worst material you could use for your transfer cup. Aluminium has one of the highest thermal conductivities, only exceeded by copper and gold. http://www.engineeringtoolbox.com/thermal-conductivity-d_429.html This means that it sucks the heat right out of your plastic, lowering the temp and causing your cold cracks. If you need to transfer, use a ceramic material or another pyrex, but why transfer? If you are pouring in such a cold enviroment, consider making a PoP jacket for your pyrex cups. Ghost baits wrote a very good artical on this, about a year ago. http://www.tackleunderground.com/forum/soft-plastics/11472-keep-your-pyrex-cup-plastic-warm-dipping-multiple-color-pours.html Make sure the PoP is fully cured before use. PoP is an extremely good insulator. Dave Edited March 2, 2009 by Vodkaman Quote Link to comment Share on other sites More sharing options...
squigster Posted March 2, 2009 Author Report Share Posted March 2, 2009 Thanks for the comments guys. The reason I use the aluminum cups is 1. I cannot pour a fine enough stream with the Pyrex cup and 2. These cups were suggested when i started by Lurecraft and Del if my memory serves me right. I am pouring relatively small baits so I need flow control. Do they make anything better that would hold the heat besides Pyrex? I am assuming someone pours with something other than Pyrex and has a system worked out. I will try the Pyrex again but by hands are a bit shakey. Quote Link to comment Share on other sites More sharing options...
Vodkaman Posted March 2, 2009 Report Share Posted March 2, 2009 I get your point, that is a tough one. A good tip that has been posted a few times, is not to over load the pyrex cup. 1/3rd full pours much better than 2/3 full. Build up something to rest your pouring arm on. A stack of phone books will bo for a start. Once you find a comfortable pouring position, build a custom arm rest. Dave Quote Link to comment Share on other sites More sharing options...
Richard Prager Posted March 2, 2009 Report Share Posted March 2, 2009 Pyrex makes a smaller one cup size that makes for easier pouring of smaller baits. If you still want to use the pans, you might try putting them on an electric griddle after transferring the plastic to the cup. You can find them at walmart for $20 Quote Link to comment Share on other sites More sharing options...
nova Posted March 2, 2009 Report Share Posted March 2, 2009 When I buy pyrex I wait until they come on sale and I buy the 3 pack; 4 cup, 2 cup, and 1 cup in a set. I usually get them for $12. The one cup is good for detail work. As for cold cracks; I use a lot of POP molds and before I start pouring the baits I always preheat the molds buy melting scrap plastic(not used) and pour it into the molds while I'm getting the real batch ready to pour. This will preheat the mold to minimize the coldcracks. When sealing the POP molds I always apply the frist coat of thinned epoxy to the entire pouring side of the mold. www.novalures.com Quote Link to comment Share on other sites More sharing options...
