BrownPigs Posted October 26, 2010 Report Share Posted October 26, 2010 Has anyone tried Smooth On 121/30 for making molds? I have been using Alumilite high strength 2 and 3 but the hobby store in my area just got that Smooth On 121/30. Is it worth using? Quote Link to comment Share on other sites More sharing options...
BrownPigs Posted October 27, 2010 Author Report Share Posted October 27, 2010 I was looking on the Smooth On website and I see that the PMC 121 series is a Urethane rubber. So of course I have to ask what are the differences performance-wise between Urethane rubber and silicone rubber? Quote Link to comment Share on other sites More sharing options...
BrownPigs Posted October 28, 2010 Author Report Share Posted October 28, 2010 I emailed smooth on and here is the response I got from Jason Reese: There are many differences between urethane rubber and silicone rubber. Silicone rarely needs a release agent when making molds or casting urethane resin such as Featherlite, urethane rubber always does. This may be a concern for you if you are going to paint your castings. More info on release agents can be found here: http://www.smooth-on.com/faq_display.php?faq_id=15&cID=1 A PMC 121 mold can give you a very long 'library life', an OOMOO mold will last about 12 months in storage. More info on library life can be found here: http://www.smooth-on.com/faq_display.php?faq_id=5&cID=2 Those are a couple of the main differences between the two materials you mentioned, please let me know if you have further questions. Also, our new Mold Star 15 can give you the best of both worlds, with a long library life and no release agent needed in most cases. More info on Mold Star 15 can be found here: http://www.smooth-on.com/index.php?cPath=1341 Quote Link to comment Share on other sites More sharing options...
