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How to determine the best casting material for your project? Answered

I want to cast a set of 4 Argosy Airstream Center Caps. They can no longer be purchased. The originals were light weight but chipped easily. What is the best material to cast them out of? I have two of the originals to work from.

1 Replies

Paige RussellBest Answer (author)2017-02-27

Hi BelvaB1,

You have amazing timing! I just got back from Modernism week in Palm Springs where I saw an exhibit of over 90 vintage trailers. I saw an Argosy – and so many other beauties!

Ok, now to your project. I would recommend using Smooth-On's Smooth-Cast® 57D urethane resin. It's a semi-rigid plastic that has great impact resistance. The other bonus of this material is that it's also really great for slush casting, which means you could just make a one part block mold of the cap and then roll the quick curing 57D around the inside of the mold until the entire surface is covered evenly and the material is set (about 3 minutes). You would repeat this 2-3 times until you've reached your desired part thickness. This material is also tint-able, using Smooth-On's So Strong pigments, so you should be able to color match the new parts to the the originals with a bit of color mixing and texting.

If there is a shape to the underside of the part that is important to replicate, I would recommend using the same 57D casting material and instead make a three part silicone mold to cast into. Here's a great instructable on how to make a three part mold:


If you have any more questions, please let me know!


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