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Tip: Priming and paint

R

Ronald Sutton

Member
As a tech counselor I get called in to look over builders shoulders by request. If there is one over all complaint I have voiced; it is the priming of parts that mate to riveted surfaces. Often times there is too much primer used. When the finished parts are riveted together, the clinched rivet squeezes out the excess primer and shows a depressed area around that rivet. As you look down the line of rivets you can see it leaves a wavy line.
What is too much primer ???:confused: I have been taught to prime just enough to see the base metal showing through the primed surface, all most a fog effect. Zinc chromate is a standard of the industry, and I use the simple spray cans.:rolleyes:
 
Many builders are now using primers that have no intrinsic corrosion resistance except for being a barrier film. These primers need to be thicker to provide full coverage for protection.

With zinc chromate, a lighter coverage can be used because the zinc is protectve.

Dave
 
David Paule said:
Many builders are now using primers that have no intrinsic corrosion resistance except for being a barrier film. These primers need to be thicker to provide full coverage for protection.

With zinc chromate, a lighter coverage can be used because the zinc is protectve.

Dave
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Or the strontium chromate in the AKZO epoxy primer which acts just like zinc chromate.

0.0010 to 0.0013 inch thickness is recommended and it will look semi-transparent.
 
Be careful with zinc chromate. Unlike some chemicals that might cause cancer, zinc chromat DOES cause cancer. It is a known, proven carcinogen.
 
Alodine (r) pen

Many of us started using the Alodine(r) pen for the rivet lines (original topic) several years ago. It eliminates the spray and when used per directions is a safe method to protect specific areas such as rivet lines. A single pen goes a long way and is extremely convenient.

P.S. The link I provided is not an endorsement. There are other sources at varying prices.
 
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Alodine touch n Prep Pen.
Not sure how far each pen goes, or lasts.
I realise this is a difficult question but how many would you anticipate you would use for a whole kit if used for rivet lines only on mating surfaces?
My kit is RV-12.
John
 
I can't answer your question since I haven't finished my wings yet. But I wouldn't buy but one pen at a time since it does have a shelf life. Keeping it in a refrigerator extends the shelf life.
 
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$100 for an Alodine pen versus $42 for a gallon of the stuff? No thanks. I'll stick to papr towels, acid brushes and scotchbrite.
 
;);)
aerhed said:
$100 for an Alodine pen versus $42 for a gallon of the stuff? No thanks. I'll stick to papr towels, acid brushes and scotchbrite.
Click to expand...

I didn't pay near that much for it. Best I remember, it was $45 and one pen is probably enough for a whole RV.

I only used that link because it had a picture. Somehow I knew when I posted that "P.S." that someone wouldn't understand what I meant.

And don't knock it 'til you've tried it. :cool:

And one more thing, I never said the pen was the best method. It's just another option to consider, offered in the spirit of sharing and education. ;)

IIRC, I got mine from Stein, and it looks like the price has gone up as has a lot of things in the last 5 years since I bought mine. Let's see, we're building a $100,000 plane and someone is quibbling over $25 for something that's different. Yeah, sounds about right. :rolleyes:
 
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