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Painting anodized rivets?
- Thread starter mstrauss
- Start date
You (or your paint shop) will scuff the surface of the aluminum panels and the rivets with a scotchbrite pad or something similar prior to spraying . This will promote adhesion. Hundreds of thousands of airplanes have been painted this way with no issues.
Makes perfect sense, thanks for the response. Let me expand a bit on the question with a specific example. You have primed you parts and riveted them together as per plans, and now wish to paint the interior of the plane. You have primed surfaces and anodized rivet heads all throughout the interior. I don't intend to paint all of the interior, as I will be installing panels, but there are definitely areas that will not be covered, so I want to paint them. I will give the primer a light sanding to promote adhesion, but not enough to sand the anodization off the rivet heads. Is that going to create a problem for the paint?
MS20426 (flush head) and MS20470 (universal head) rivets specify the following:
Finish: Chemical surface treatment MIL-C-5541 Class 1A, yellow. Also, see procurement specification Anodize MIL-A-8625 Type II Class 1, clear is specified on aluminum alloys 1100, 2017 (most common for our airplanes), 2219, 5056 and 7050 rivets by adding the letter 'A' following the last digit of the dash number.
MIL-C-5541 specifies:
Scope: This specification covers the requirements for two classes of chemical conversion coatings formed by the reaction of chemical conversion materials and the surfaces of aluminum and aluminum alloys ... The coating also provides a surface having better paint adhesion than uncoated aluminum.
Class 1A - For maximum protection against corrosion, for surfaces to be painted or left unpainted.
So for a typical rivet part number MS20426AD3-3, there is no 'A' following the last digit of the dash number, so the finish is not anodized. Therefore the finish is per MIL-C-5541 which is a conversion coating (ie. Alodine) which is compatible with paint. No preparation prior to paint is required except to clean to ensure no oils or contaminants are present.
Finish: Chemical surface treatment MIL-C-5541 Class 1A, yellow. Also, see procurement specification Anodize MIL-A-8625 Type II Class 1, clear is specified on aluminum alloys 1100, 2017 (most common for our airplanes), 2219, 5056 and 7050 rivets by adding the letter 'A' following the last digit of the dash number.
MIL-C-5541 specifies:
Scope: This specification covers the requirements for two classes of chemical conversion coatings formed by the reaction of chemical conversion materials and the surfaces of aluminum and aluminum alloys ... The coating also provides a surface having better paint adhesion than uncoated aluminum.
Class 1A - For maximum protection against corrosion, for surfaces to be painted or left unpainted.
So for a typical rivet part number MS20426AD3-3, there is no 'A' following the last digit of the dash number, so the finish is not anodized. Therefore the finish is per MIL-C-5541 which is a conversion coating (ie. Alodine) which is compatible with paint. No preparation prior to paint is required except to clean to ensure no oils or contaminants are present.
I just painted my interior with Jetflex WR. i had primed with Ekoprime, but typically the rivets were not primed. I gave all the areas I intended to paint a light sand with a maroon scotchbrite, including the rivet heads. Then I thoroughly vacuumed everything with a shop vac and wiped everything down with a damp rag. I masked everything off and gave it a second wipe with a damp cloth. Lastly, I used a tack cloth right before I sprayed it with an HVLP gun. Turned out great. Can’t speak to the durability yet, but seems to have adhered well. YMMV
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Anodizing is a step better than Alodine. I'm in the heavy jet industry, and deal with both on everything. Forget about it, move on. Other than 1100-"O" (soft non structural) all rivets are anodized. You should be more worried if they aren't anodized.
You mean *alodined*, right?
Unless there's a letter after the length, that is to say that it's blank, it's *alodined*. Ref. terrye's post above.
AN426-AD-4-5 Alodined
AN2426-AD-4-5A Anodized
But you're right...everything AFAIK on an RV uses alodined rivets. No issues with painting them.
Didn't get into all the details, but Terrye's post is more correct than mine...fact is, you are not using uncoated rivets, and the anodize poses no paint issues.
