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thill

Mold, PoP admixture suggestions for better results

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Greetings all. I'm new here, but I've been making soft plastics and jigs for about 9 years now. Wish I had found this place years ago. Might have saved me a lot of trouble!

Anyway, for you who use plaster of paris (PoP) to make molds with, if you add about 1/3 Rocktite hydraulic cement to your plaster, and mix well BEFORE adding water, you will end up with a MUCH MUCH smoother, more durable mold. It sets in about the same amount of time, but will not pull nearly as much moisture from the air as pop and the edges will not chip on 2-sided molds.

I've got jigging spoon molds that have lasted me years, and are still fine. Not quite as perfect as the molds I've made with aluminum and a Dremel tool, but pretty darn good nonetheless.

Also, "metal chick" on ebay sells some nice machined aluminum for mold stock. Print your design from your computer, then cut out the outline, making a stencil. Use a fine-tip sharpie, flipping it to make mirror sides, and then use the dremel to bore it out. I use a mini cove bit, then a stone to smooth everything, and the results have been great!

Also, casting resin from Chemical concepts makes one heck of a plastic mold, but it doesn't cool like the aluminum ones. Still, they work great.

They also sell urethane mold resin that works GREAT for pour lures like Sluggos and BA's. I'm still using my originals, almost a decade later. Cheaper than the silicone, but not quite as flexible. But economical to make a bunch of molds. (and as you may know, lots of cavities to pour is a GOOD thing!)

Anyway, I've been doing a lot of reading here, so I thought I should chip in with a few hints. Probably old news to most of you, but hopefully, it may help someone.

Best wishes.

-TH

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Mr. thill...

Welcome to the TU fray. Having you on campus is going to be a real treat. In your first few posts, you have made several nice contributions to the brain thrust. I think you know how addictive tackle making is, so relax, enjoy, and we look forward to seeing some of your specialties posted into the gallery as time goes on. See you on campus. ;)

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Bruce,

Thanks for the welcome!

I forgot to mention that if Rocktite isn't available to mix with POP, regular Portland Cement works well, too. Really makes the mold a lot more durable.

No need for me to post pics of my stuff, since most of mine are are just home pours of commercial lures. I got into it to save money. I have a secret weapon lure, but I've stopped posting pictures of them. Gotta keep something to myself! :)

Looking forward to interesting exchanges of ideas. Best wishes!

-TH

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I mix about 20% PVA (elmers glue) with the water. This improves the strength and resistance to chipping. Also the surface is no longer dusty.

I'm still experimenting with the proportions. If you add too much PVA, the bubbles become more of a problem as the viscosity of the water increases.

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TK1,

I use them to pour lead all the time.

Braveviper,

If you mix the rocktite or portland into your POP, it will last for years, IF you make sure it cures and dries properly. To do this, first you let the lure harden, then make sure everything is right. Then, WET the mold again after a day or so. This completes the cure. After about 3 days, you can put the mold in a 250 degree oven for a couple of hours to help speed the drying process. After that, I typically spray high-temperature spray paint on the molds to seal them and make them smoother.

This takes a little more time, but the molds will last for years.

Smallie,

I don't know the numbers, but they are standard burrs and stones I get really cheap from Harbor freight tools. The stones wear out pretty quickly, but work well while they last. The burrs work well, but you have to clear them from time to time.

On the website, www.uscomposites.com, they sell RTV Silicone, Casting Resin and mold resins. Look carefully, because they are there!

I hope this is helpful!

-TH

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The original post said Chemical Concepts - that is what through me.

US Composites has a lot of great products for mold making. They are big with the guys making carbon fiber parts for cars. They also a good source of material for making repairs to the gel coat on your boat.

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A fantastic alternative to regular POP is Hydrostone casting plaster. It's a mixture of portland cement and POP, but it captures detail at a very fine level (finer than POP). It's used in making casts of fossils and replicas of highly textured sculptures. Very tough stuff and inexpensive to boot. Sets up in about 15-20 minutes. Here's a link to where I get mine: http://plaster.com/HYDROSTONE.html

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Ultracal is a bit weaker than Hydrostone and more prone to chipping or wear. It's still a much better option than POP, but I tend to be a bit rough on my tools and materials and with Hydrostone I have even dropped molds on a concrete floor (but not from very high) and not had them shatter or crack. Still, I don't recommend doing that!

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A fantastic alternative to regular POP is Hydrostone casting plaster. It's a mixture of portland cement and POP, but it captures detail at a very fine level (finer than POP). It's used in making casts of fossils and replicas of highly textured sculptures. Very tough stuff and inexpensive to boot. Sets up in about 15-20 minutes. Here's a link to where I get mine: Plaster.com - HYDRO-STONE
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