aluminum resin?

[chris02719]

I recently ended up with a few older resin truck conversions of unknown origin, they are cast in a dark grey resin that seems to be impregnated with aluminum powder, has anyone encountered this before?  How is it to work with?  I would assume that it would be more brittle than typical resins.  Anything else I need to watch out for?  One of them has the quarter fenders molded to it and they would have to be removed if I were looking to make the hood operate.  Any advantages of this type of resin over others?  Thanks for the help.

[SfanGoch]

Metal Powders - For Real Metal Cold Castings

[Ace-Garageguy]

Aluminum, bronze, iron and even carbon powders are routinely added to resin systems to vary the performance characteristics and capabilities for specific applications. Adding aluminum powder makes a brittle resin more easy to machine or tap for threads. Bronze powder is added for making "bronze cold-cast" lower-cost sculpture that doesn't have to use molten metal. Iron filings or powder can dramatically increase a resin's abrasion resistance and resistance to cracking under pressure (iron-filled resin systems have been used to make matched press dies for shaping sheet-metal into stamped parts...as thick as 1/8 of an inch of sheet steel has been successfully stamped as far back as the early 1990s). Carbon powder is sometimes added to make a resin electrically conductive.

In general, IF your resin parts have metal powder or filings added, they'll be tougher and harder to cut and shape than un-modified resins.

Frankly, I can't see any good reason for adding powdered aluminum to a model car resin casting system. Are you absolutely certain your resin parts aren't just made of a gray tinted resin, kinda like JB weld?

[chris02719]

They're definitely not like jb weld.  They're a lot heavier than a typical resin part, they have a real grainy texture where the pour spout was.  They also have a shine in places that is definitely metallic, almost like an older pewter piece.  It's not pewter.  I'm imagining that these castings date to the 80's, possibly from illini replicas?  I haven't had a chance to really play around with them or get any pics.    

[Mark]

At least one of the guys doing the "heavy commercial" stuff in the Eighties was using resin with aluminum powder.  Why, who knows...maybe it was thought to be stronger, perhaps it was easier to do minor repairs on blemished castings (making the repair less detectable, part could still be considered "first quality"), maybe it was thought that the heavier castings had a better/more substantial feel.  I don't recall ever seeing any car conversion or re-pop parts that used it.