experimenting with fillet material

[Chris Belcher]

I did an interesting experiment last night with Brodak Super Fil. I always wanted to see if one could use a syringe to apply to the fillet. So...mixed up a batch...added some denatured alcohol to thin just enough to get it in a 10 ml syringe (with no needle) and voila...it pipes out just like a miniature caulking gun. I used a popsicle stick to smooth and got the best fillet I have ever done. One careful pass with the stick and no more smoothing was required. I did this on some test pieces at different angles and the results were really promising. I left some of the material out to check for hardness, brittlenes and flexibilty. This morning I was able to sand, bend and tried picking at it with an exacto knife...nothing seemed different. Now this is not a true experiment....yet...becase I did not do a control with epoxy WITHOUT denatured alcohol. So the question..is there any resason not to thin Super Fil with denatured alcohol? re my fillets going to fall off in mid air?

[Mike Griffin]

Hi Chris,

I have thinned SuperFil many times with just regular rubbing alcohol and none of my wings have flown off yet.  I also keep an expoxy cup of alcohol close and dip my finger in it before I smooth out the fillet.

Mike

[Steve Helmick]

Denatured Alcohol is ok, AKA "Shellac Thinner" from the hardware or paint store. I would not use "rubbing alcohol" because it has water in it. If in doubt, read the label first. I think methanol alcohol would be ok, but I'm not a chemist. I haven't even stayed at a Holiday Inn Express, but did take high school and college chemistry.

Acetone or Lacquer Thinner would probably work ok, but would be likely to cause brittleness. At least, it appeared so, the one time I did that, so didn't do it again.  Steve

[FLOYD CARTER]

I've had good luck with Brodak Super-Fil epoxy.  first mixed with lots of "micro balloons" and thinned with ordinary butyrate thinner.  The thinner evaporates long before the epoxy begins to set, so the thinner isn't involved in the hardening process.

I simply glob it on and use a spare finger to smooth it out.  No need for a syringe.

Floyd

[Motorman]

I'm wondering if you can use superfil to stick down fiberglass or is it too dry. I've got a spot that needs filler and needs to be glassed. Should I let the filler dry then use epoxy for the glass or can I just put the glass over the wet superfil?


MM

[Phil Krankowski]

If the two epoxy products are compatible then it should work just fine to lay one then when the first is "green" lay the second over it.  I would recommend testing the products together unless the mfgs already confirm compatibility.

If the chemistry is not compatible then I would expect the joint to become funny, and/or delaminate under flexing.

One neat thing about laying up while a previous layer is not cured ("green") the fresh layer will chemically interlink to the previous without any prep necessary.  Most epoxy will form a layer of "blush" which is a waxy residue driven out by curing.  This layer needs removed and the material sanded.  Ammonia and water tend to cut blush pretty well.

Phil

[Howard Rush]

Thanks, Phil.  Good information.