Rattle Primer Issue

[N329JR]

I would recommend that a degreasing operation be performed PRIOR to scuffing... or at least scuffing wet with cleaner (MEK, acetone, etc). Otherwise you may run the risk of impregnating contaminants into the aluminum that could cause poor primer adhesion.
... and then of course your favorite final cleaning method immediately prior to priming.
My 1.5 cents

[Robert Anglin]

Originally Posted by amaris

Thanks. If alcohol will remove the oil and contaminants, is there any reason to do acetone too? I don't want to add another step in cleaning if one will work fine.

We use the 988 or 2027 for most every thing inside and have had very good luck with Scotch- Bright, then clean with lacquer thinner. The only thing we use Acetone for is fiber glass clean-up or thinning epoxy. The acetone will leave some trace residue on the surface. Clean white paper towels will tell you when you have the surface clean of all residue. The kind that don't fall apart. Don't touch the peace with your bear hand after you get it clean, your skin oil will become a release
agent. Hope this helps, yours, R.E.A. III #80888

[amaris]

Originally Posted by N329JR

I would recommend that a degreasing operation be performed PRIOR to scuffing... or at least scuffing wet with cleaner (MEK, acetone, etc). Otherwise you may run the risk of impregnating contaminants into the aluminum that could cause poor primer adhesion.
... and then of course your favorite final cleaning method immediately prior to priming.
My 1.5 cents

I've been using the scotch-brite with the alumiprep to scrub and scuff the metal. Then washing and drying and then acetone.

[N804RV]

Originally Posted by Robert Anglin

...Don't touch the peace with your bare (or beer -Ken) hand after you get it clean, your skin oil will become a release
agent...

Excellent point! Boxes of powder free nitrile gloves can be had, cheap, on Amazon.com.

[RVbySDI]

Originally Posted by N804RV

Excellent point! Boxes of powder free nitrile gloves can be had, cheap, on Amazon.com.

Or ask your family dentist. I did so and he just gave me a box for free whenever I was in for my cleanings.

[amaris]

Originally Posted by N804RV

Excellent point! Boxes of powder free nitrile gloves can be had, cheap, on Amazon.com.

Yep, or Costco (Sams too). That's where I get mine from.

[byoung]

I've had this same flaking problem maybe 5% of the time. I wish I knew what the problem was too.

My process is dawn detergent/scotch brite scrub, Metal prep/scotch brite scrub, air dry, lacquer thinner wipe down with a clean cotton rag (wearing nitrite gloves) , then SEM rattle can. I'm in the middle of the fuselage build now (slow build kits) so I have run this process many times.

The remedy always works - light scuff with scotch brite pad, lacquer thinner wipe, and re-spray. That makes me think that it is a surface containment problem, since the frequency of occurrence is pretty low maybe I just miss these areas?

[amaris]

Originally Posted by byoung

I've had this same flaking problem maybe 5% of the time. I wish I knew what the problem was too.

My process is dawn detergent/scotch brite scrub, Metal prep/scotch brite scrub, air dry, lacquer thinner wipe down with a clean cotton rag (wearing nitrite gloves) , then SEM rattle can. I'm in the middle of the fuselage build now (slow build kits) so I have run this process many times.

The remedy always works - light scuff with scotch brite pad, lacquer thinner wipe, and re-spray. That makes me think that it is a surface containment problem, since the frequency of occurrence is pretty low maybe I just miss these areas?

I'm suspecting it's a moisture issue or residue with acetone. I've gone back and touched up the areas with a dry scrub then wipe down, dry it and then prime and the area always turns out fine. I'm going to try alcohol and a little time with the blow dryer to see if that helps.

[johnbright]

I'm told acetone removes oil, so you can't leave out the acetone step, and isopropyl alcohol removes acetone residue. This from a highly experienced composite house... for cleaning molds and for cleaning product prior to painting. They say wipe with acetone in one direction followed by wipe with isopropyl alcohol in one direction. They don't like MEK for health reasons. I don't know if MEK leaves a residue. I have used Coleman lantern fuel with no post alcohol wipe followed by etch primer, the kind you mix and spray, with no problem but I'm thinking the composite house has a better way because of their professional expertise.

[wirejock]

There's some sort of contaminant causing the bubbles.
Try scrubbing with Bon Ami cleanser then a thorough rinse, dry and spray.