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DP40 is an Epoxy Chromate primer/sealer.
Its used in aircraft restoration work because it inhibits corrosion
on both steel and aluminum. I stopped using lacquer based
zinc-chromate and have switched to DP40.
The chromate causes it to also self-etch the base metal. It sticks
to metal like nothing else I have ever used. It provides a sealing
layer that prevents moisture (or PAINT SOLVENTS) from reaching what's
under it.
If its fully cured, you should scuff sand it before top coating. If
you don't do this, the top coat may not fully bond. I have seen this
happen, its about a 50/50 chance if you don't scuff sand with
something like scotch brite/fine pads.
If I were using in on aluminum LBC parts, I would follow the same
procedure used on aircraft:
1. Wash with an alkaline soap; like simple green, 409, ... rinse
with lots of fresh water.
2. Dip or wash with Aluminum metal prep (acid) to dissolve any
traced of oxide. Auminumn oxide breeds more aluminum oxide so you want
to remove every trace of it. Its the white powder you see around bolt
holes, where aluminum mates to steel, etc. Rinse very well.
3. Optional; if the part is exposed to a lot of moisture; an
Alodine treatment will add more protection. Dip or wash the parts,
keep them wet, follow the directions for timing. And then rinse very
well. Alodine is toxic, wash up real well and be careful how you
store and dispose of it.
4. Make sure its really dry
5. Prime with DP40. For aluminum, the correct film thickness is
reached when you can still read writing on the aluminum through the
primer, any thicker than that is ok but wastes the DP40 and adds
weight (which may be a problem for Triumph-Tractors) However, any
areas where steel will contact the aluminum, I would put an extra
heavy coat.
6. The sanding dust from DP40 is toxic (chromate). Wear a
respirator (not a dust mask!) if you dry sand it.
Hope this is helpfull;
Bob_ollerton@priacc.com
San Diego, CA.
79'MGB; 53'TD; 3 airplanes, no house.
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