Urethanes and silicones and foams, oh my!

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Rocket Al

Well-Known Member
Jan 18, 2009
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Just thought that I would post a few links to a pretty economical site for getting molding and casting materials that I use for work as well as rocketry purposes. The company is called Smooth-On, and their main website ishttps://www.smooth-on.com

Now, let's start the linking to their internal pages...

One of the first things that folks look for seems to be fast cast two part liquid plastic, with many folks starting with Aluma-Lite. I've used it, but it is a metal filled (Aluma!) plastic which may be heavier than you need. Smooth-On's plastics line has a wide variety of resins available, including water clear and feather-lite plastics. While the cure times are longer than things like Cast-Master and Aluma-Lite, the longer cure time results in less shrinkage, which is an issue with some of the yellow urethane cones that you get from some vendors, where even though the mold was made off of an available plastic cone, the urethane copies were done with an extra fast cure urethane that shrank too much. the casting urethane page is at https://www.smooth-on.com/Urethane-Plastic-a/c5_1120/index.html

Their tin-based silicone page can be found at https://www.smooth-on.com/Silicone-Rubber-an/c2_1113/index.html . I have used their Mold-max 30 for creating molds, and it works best when NOT fast catalyzed. using a fast cat in it causes excessive shrinkage which is particularly noticeable in larger molds. I have also used their translucent silicones and rubber glass, but those materials really don't have many applications in rocketry.

Finally, their rigid urethane foam page is at https://www.smooth-on.com/Rigid-and-Flexible/c10_1122/index.html and the variety of densities they have is excellent. This is the stuff that can be used for foaming fin cans, filling hollow nosecones, etc. Compare the prices to rocket vendors online. the nice thing is that, being manufacturers, you know the product is fresh and sealed, and the product support is top notch, whether buying directly from Smooth-On, or one of their distributors.

I am not a sales rep for Smooth-On, just a happy customer who works in a business where I am responsible for balancing cost and quality for my Dark Overlord. Any questions, please feel free to ask

I have used their Mold Max 30, & OOMOO silicone rubbers and some of their plastics.

The trail sets are nice to play with new materials, you do pay more that way.

I do agree that you pay more for their trial packs. however, you need to compare it to what you can get elsewhere. As i get it in either 55 gallon or at least 5 gallon kits, I spend way less than most would pay for a 1 gallon kit, which is still less expensive than Silicones Inc's GI-1000 or Walco's comparable Shore 30 silicone (which IIRC is VI-1065) fact is, you CAN get a smaller than a gallon kit from Smooth-On, which you would be hard pressed to get from anyone else.