painting without primer

[glenn654]

I have been thinking lately that it may not be necessary to prime the exterior before painting but rather lightly scuff the skin and paint.

Has this method been used much and how well does it work?

Glenn Wilkinson

[Bill_H]

In my discussions with the paint experts for IMRON, regarding both single stage and base coat/clear coat options, the idea about skipping primer simply never came up. A lot of details about proper aluminum prep were discussed, but not that. http://www.vansairforce.com/communit...ad.php?t=67760

If car companies could save even a dollar per car by skipping primer, you can bet they would have figured out that option.

[Mike D]

Here is just one data point.
The canopy skirt was not primed on my -6. It flakes off in big chunks. Around a sq inch at a time.
The main fairings were not primed. They are being striped of paint by rain and wind. Just pealing off.
The rest of the plane was primed and the paint has lasted 15 years. Some chips, but not much bigger chunks.

[Kyle Boatright]

Back in the day, Van's didn't prime their demo aircraft. The paint on those seemed to hold up reasonably well. If you're not going to prime, paint adhesion probably comes down to how well you clean, scotchbrite, and etch the surfaces prior to paint.

One alternative to no primer under your paint is a VERY thin coat of self-etching primer.

[brad walton]

You need etching primer or an alodined process on aluminum. Most manufacturers have the requirements for painting different surfaces on their websites. Check the one whose product you plan to use.

[xblueh2o]

Originally Posted by glenn654

Has this method been used much and how well does it work?

I have seen it done and the results were pretty much what Mike D reported.
Looks fine for a short period and then just starts ejecting itself off the airframe.

[glenn654]

Thanks Guys.

Pretty much what I thought but was curious.

Will use self-etching epoxy primer.

Glenn Wilkinson

[vfrazier]

20 years ago, when I had a LOT less disposable income, I painted my RV-4 w/o primer. Just scuff and paint. Adhesion was very poor. I suspect that I could have blasted it all off with a power washer. I'd not do it again.

It looked great and saved a lot of money, but I'll wager that the paint is LOOOOOONGGG gone. I haven't seen the plane in years.

[agough277]

a friend painted with Imron with just alodine primer. He checked with the paint manufacturer who advised alodine was sufficient for Imron,there are some 11 sources of corosion for which alodine protect 7 as I recall. Id at least do alodine which adds little weight.