Aluminum powder in resin as a filler?

[imagineer]

A little background…
I while back, I cut an opening in the batwing fairing on my motorcycle and added a NACA style duct (https://www.pegasusautoracing.com/pr...p?Product=3627) to try and balance off the pressure differential behind the fairing, all in an attempt to reduce helmet buffeting. I wasn’t happy with the results and recently 3-D printed a different design duct and over the weekend, removed the purchased duct and installed my design.

Not necessary information…
The batwing fairing (Memphis Shades) is made from Lucite and the duct is 3-D printed using PLA (polylactic acid). I used 2 part epoxy to first bond the duct to the fairing, and then using fiberglas and resin, completed the attachment. 

Here’s the start of the question… 
The resin set up fine and hardened as it was supposed to. However (after 26 hours), the very top layer of the surface is still very wet and sticky. I’m fairly certain it’s not a result of a bad resin/hardener ratio because the base and excess set up great. I’m also certain that ambient temperature isn’t a factor because it’s been in the 90’s for a week now. 

I’ve read that this is a common problem brought on by the coating of resin not being thick enough to generate its own heat for the needed chemical reaction. In these situations, folks can either wait it out, sometimes 2-3 weeks, for the resin to finally harden, or they can “dust” it with a dry filler material. The dry filler will absorb into the wet resin, building up a thick enough layer to be sanded & finished. Being the impatient sort, I’d rather go with the filler approach.

Almost to the question… 
The, recommended dry filler materials are talc, cured bondo powder and aluminum powder. Whereas I have talcum powder available, I don’t have any cured bondo to grind down. I do, on the other hand, have more ultra fine aluminum powder than you can imagine (a product used where I work).

Finally the question…
Has anyone out there added aluminum powder as filler to epoxy or fiberglass resin? If so, did it affect the cure time and was it difficult to shape and sand after curing?

[Tonik]

I can't answer your question directly but I can tell you this.  Bondo is mostly talc and resin, so adding talc seems to be ok to me.  And there are many bondo's that have aluminum added, so adding that seems ok to me also

I would go for it, worst case you sand it down and apply a layer over the top.

 

[motocat12]

A hot worklamp could help heat cure it.

heck baking soda works with superglue.  You're going to do a test piece anyway, right?

And because it's fun to say and picture, microballoons

[Gixxus Christ!]

Aluminum powder should be fine, you're gonna grind it down anyway.

[imagineer]

FWIW, the problem is solved... An Amish employee here at my plant has a side business building strip built canoes and kayaks. Just about everyday, this poor soul wreaks of resin. I shared my tale of woe with him, and his suggestion was simply, "sand it out". 

As he suggested, I started with 120 grit and lightly sanded all the sticky surfaces. The paper gummed up fairly quickly, but after 2 pieces, the entire surface of the resin coated duct was sanded and no longer sticky. Again, following his suggestion, I did all the needed sanding to smooth down edges and develop a consistent white-ish surface, after which I cleaned it well using a small amount of acetone on a rag. Next I mixed a small batch of resin, using 1.5x the recommended hardener. Working quickly, I painted another coating of just resin on the sanded surfaces. He said to keep painting on layers until the resin starts to thicken and at that point, stop.

I checked the project this morning and the fresh layer of resin was only a little tacky. It will sit in my 90+ degree workshop until mid day when I'll move it out into the sun. 

Edited July 26, 2016 by imagineer