Re: Resin Casting
Response To:
Re: Resin Casting ()

David Walser
Doug -- Casting can, but need not, be a fairly involved process.

Much of Zac's casting uses Alumilite Clear or Alumilite White. All of mine has been with Alumilite Clear Slow (which Zac also uses). These resins are urethane casing resins that allow for relatively large castings. They accept a variety of dyes, tints, powders that allow a virtually unlimited range of visual effects. Once fully cured, the blanks turn very well -- not nearly as chippy as many polyester and epoxy resins are. These resins play nice with wood, metal (such as aluminium), and many plastics. There are few things that cannot be cast in Alumilite.

That is the upside of Alumilite, the down sides are these: Alumilite is hydrophobic. Or maybe it just really likes water and gets really excited in its presence. Whatever Alumilite's views on water, it foams up when in its presence. Thus, any wood you use needs to be perfectly dry. Also, Alumilite has a very short pot life. Of the three, Alumilite Clear Slow has the longest pot life -- a whopping 12 minutes. Which means that any air bubbles introduced into the resin in the process of mixing and pouring will not have enough time to escape the resin before it hardens. To deal with this problem, most casters use a pressure pot -- to compress the air bubbles so they cannot be seen by the naked eye. Twelve minutes is not a lot of time in which to mix, add embellishments, pour, and get the mold into the pressure pot. With good organization and practice, you'll find 12 minutes (or 7 minutes for Alumilite Clear) sufficient time.

There are epoxy resins that cure slowly enough that you don't need a pressure pot to eliminate visible bubbles. If you're casting wood with the epoxy, you'll want to seal the outside surface of the epoxy to prevent air migrating from the wood into the resin. These resins are used by a number of turners. (There are several brands, including some from Alumilite.) The process is simpler and the resulting blanks are good quality (although most epoxy resins don't turn quite as well as Alumilite White, Clear, or Clear Slow, many turners don't notice much of a difference).

I haven't switched to epoxy because epoxy resins tend to be more expensive than Alumilite's urethane resins. And, I already have a pressure pot and the knowledge base to cast successfully with Alumilite Clear Slow. Finally, most of the epoxy resins don't allow for deep casting -- generally the casing can be no more than 2" thick. Which make them difficult to use for casting a larger blank, such as a pepper mill. Alumilite Clear Slow allows for casting larger blanks. You can work around the casting depth limitation of epoxy resins by making multiple pours, which is what I do when I'm exceeding Clear Slow's limitations. However, I'd prefer not to do that if it's not necessary.

One last thing: Zac has an e-book on casting. It's designed to teach a newbie the basics, help him or her decide what resin to use, which equipment is needed, etc. By the time he published the book, I was already up and running, so I've never bought the book. I've heard good things about it.


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