kevtherev Posted August 7, 2014 Report Share Posted August 7, 2014 Made one with water catalyst which worked pretty well. Would like lower viscosity and was planning to use mineral spirits to mix into the silicon first then the water to catalyze. Any suggestions or thoughts? Thanks. Quote Link to comment Share on other sites More sharing options...
Smallie Posted August 12, 2014 Report Share Posted August 12, 2014 Smooth-On, Tap Plastics and places like that sell a thinner for silicone that should work. Quote Link to comment Share on other sites More sharing options...
Anglinarcher Posted August 13, 2014 Report Share Posted August 13, 2014 If you use mineral spirits, the mineral spirits will 'evaporate' from the mold over the course of about a week. As a result, the mold will shrink. Some of us use this trick to shrink lures, by up to about a third. If you make sure the walls are nearly uniform, the mold shrinks uniformly. Water catalyst silicone. What brand? I know of no water catalyst "silicone", and I am always trying to learn. Quote Link to comment Share on other sites More sharing options...
Smallie Posted August 13, 2014 Report Share Posted August 13, 2014 If you use mineral spirits, the mineral spirits will 'evaporate' from the mold over the course of about a week. As a result, the mold will shrink. Some of us use this trick to shrink lures, by up to about a third. If you make sure the walls are nearly uniform, the mold shrinks uniformly. Water catalyst silicone. What brand? I know of no water catalyst "silicone", and I am always trying to learn. I think he means adding water to allow a thick coat of RTV to cure. There are some threads about making molds from RTV on this site. Quote Link to comment Share on other sites More sharing options...
Slammingjack Posted August 14, 2014 Report Share Posted August 14, 2014 Here is some infor. about hardware silicone. http://www.tackleunderground.com/community/index.php?/topic/27200-pouring-molds/?hl=silicone#entry209965 Quote Link to comment Share on other sites More sharing options...
mark poulson Posted August 15, 2014 Report Share Posted August 15, 2014 (edited) I have made silicone molds, too, but it is a lot of work. And I couldn't get the fine detail I wanted, or use soft masters. I had really good luck using Solarez UV cured polyester resin. Here's what I use: http://solarez.com/products/low-voc-dual-cure-polyester-resin/ I bought a quart, and it lasted a year, mainly for top coating hard baits. Once I had used it to repair the broken nose on my son's surfboard, I realized it could be used for mold making, too. I made some fine finned molds using factory soft plastics with fine fins as masters, and it copied all the details, Just be sure that you use a slick base plate to glue your masters down to, and seal the four sides down real well, too. The resin is viscous, and will find any crack or hole and run out. I didn't use a release agent when I made my mold. It would probably help in getting the mold off the base plate, but I was afraid it would interfere with getting the resin to fill all the detail. I added the resin inside the garage, and then took it out into the sun to cure. I did it in layers, so it would cure completely. I brushed on the first coat, so all the details got filled really well, set that for a minute in the sun to begin curing, brushed on a second coat, another minute in the sun, and then filled the mold box so I had at least 1/4" over the tops of the masters. I left it in the sun for half an hour to fully cure, and then took the sides off and pried it off the base. It was strong and rigid. Because the poured mold wasn't perfectly smooth on the side I poured from, I used a belt sander to flatten it, so it would lay down evenly when I poured my plastics. I had some flippers that got fully covered, so I drilled some tiny vent holes down to each one, to help them fill completely, and they do. I use spray pam as a release agent on the mold when I pour my plastics, and it works great. I don't think it will work with hard masters. Edited August 15, 2014 by mark poulson Quote Link to comment Share on other sites More sharing options...
Anglinarcher Posted August 22, 2014 Report Share Posted August 22, 2014 (edited) RTV is a two part silicone. It cures without water once the two parts are mixed. Silicone caulk and glues are solvent based silicones and they either require that little bit of water or months to cure thick blocks of it (if ever). I guess that it is a difference of definitions. RTV is room temperature vulcanization, it is not solvent based. Additionally, RTV silicones yield excellent detail, on soft masters, on hard masters, even from organic masters. Solvent based silicones tend to be ........ well that problem is what created the question in the first place. Edited August 22, 2014 by Anglinarcher Quote Link to comment Share on other sites More sharing options...
