Paint Stripping

[canyonero]

Hello all,
I have a '73 109 that I want to repaint myself. I have figured out how to get the paint on, but am having trouble figuring out the best way to get the existing paint off. I've been advised to strip it chemically, but am hesitant because of time and disposal issues. There is a soda blasting place nearby, but I have read about the powder getting into wiring harnesses and other areas and causing problems. I was curious what others have done and with how much success, I am really looking to get down to bare metal so the new stuff will last as long as the old stuff has.
Thanks in advance.

[albersj51]

Citristrip works pretty well. Scuff the area, glob it on and let it sit over night

[amcordo]

Hello all,
I have a '73 109 that I want to repaint myself. I have figured out how to get the paint on, but am having trouble figuring out the best way to get the existing paint off. I've been advised to strip it chemically, but am hesitant because of time and disposal issues. There is a soda blasting place nearby, but I have read about the powder getting into wiring harnesses and other areas and causing problems. I was curious what others have done and with how much success, I am really looking to get down to bare metal so the new stuff will last as long as the old stuff has.
Thanks in advance.


If the old stuff has lasted this long you should consider using it as your primer - just sand it down so that it's rough enough to stick, but still smooth. Start with a semi-coarse paper, graduate to a medium paper, and finish it off with super smooth. Three levels of sand paper have been working fine for me. Follow up with a coat of primer over that, lightly sand again and paint!

Failing that, soda blasting was OK when I gave it a go with one panel. It was expensive (considerably more so) when compared to my cost sending it out to be chemically dipped professionally.

[jac04]

I used Citri-Strip to get all the military paint off my Lightweight, but it did not do much at all to the factory paint.

No matter what you do, you need to be very careful around the galvanized cappings. Any chemical or mechanical stripping media that gets behind the cappings will eventually lead to paint failure.

As amcordo stated, if the original paint is still good, then use it as a foundation for your new paint. You want to avoid stripping to bare metal if at all possible. Once you get to bare aluminum, you need to do a cleaner, conversion coating, then a suitable primer before you can even think about painting.

[canyonero]

I used Citri-Strip to get all the military paint off my Lightweight, but it did not do much at all to the factory paint.

No matter what you do, you need to be very careful around the galvanized cappings. Any chemical or mechanical stripping media that gets behind the cappings will eventually lead to paint failure.

As amcordo stated, if the original paint is still good, then use it as a foundation for your new paint. You want to avoid stripping to bare metal if at all possible. Once you get to bare aluminum, you need to do a cleaner, conversion coating, then a suitable primer before you can even think about painting.

My 109 actually is Ex-Mod, so there are various color schemes, which is why I was going for bare aluminum. I was going to then use a self-etching primer, but the conversion coating you mentioned is new to me. What exactly does that entail?

[mongoswede]

brake fluid works really well on some types of paint. try pouring a little on one area over night and see if the paint has bubbled in the morning.

[albersj51]

In the next few months I'll be taking mine down to bare aluminum and repainting (current paint is not usable as a "primer"). From the advice I've received (guys that paint airplanes), take it to bare, clean it really well (I'm going to use Purple Power), use a good epoxy primer and then paint.

This may not be right, but thats what I've been planning to do.

I'd be interested to know about this conversion coating as well. I've read about it while researching, but not a lot of details. One product I read about was shark-something, but I've also read that Purple Power, which is slightly acidic, works well at cleaning and lightly etching for good adhesion with the epoxy primer.

[SafeAirOne]

I used Citri-Strip to get all the military paint off my Lightweight, but it did not do much at all to the factory paint.

Once you get to bare aluminum, you need to do a cleaner, conversion coating, then a suitable primer before you can even think about painting.

I had the same experience using a "normal" high-strength chemical stripper--The PO paint comes right off and factory paint on non-alodined ("converted") panels comes right off, but you need a jackhammer to get the factory paint off those bits that were alodined.

Conversion coating (http://en.wikipedia.org/wiki/Chromate_conversion_coating) link.

[TedW]

I had the same experience using a "normal" high-strength chemical stripper--The PO paint comes right off and factory paint on non-alodined ("converted") panels comes right off, but you need a jackhammer to get the factory paint off those bits that were alodined.

Boy, isn't that the truth. I got some really nasty paint remover from Napa - quickly bubbled away all the PO paint but left the factory coating unblemished.

[jac04]

My 109 actually is Ex-Mod, so there are various color schemes, which is why I was going for bare aluminum. I was going to then use a self-etching primer, but the conversion coating you mentioned is new to me. What exactly does that entail?
More info here:
http://pc.dupont.com/dpc/en/US/html/visitor/common/pdfs/b/product/dr/ChromaSystem/H-19290_225S.pdf

http://pc.dupont.com/dpc/en/US/html/visitor/common/pdfs/b/product/dr/ChromaSystem/H-19291_226S.pdf

If you search, you will find a lot of info on painting aluminum, especially on aircraft forums. Apparently, the conversion coating is not required when using self-etching primer. When I painted the Lightweight, any spots that went to bare metal were cleaned, scuffed & hit with a light coat of self-etching primer before being top-coated.

[TedW]

More info here:
http://pc.dupont.com/dpc/en/US/html/visitor/common/pdfs/b/product/dr/ChromaSystem/H-19290_225S.pdf

http://pc.dupont.com/dpc/en/US/html/visitor/common/pdfs/b/product/dr/ChromaSystem/H-19291_226S.pdf

If you search, you will find a lot of info on painting aluminum, especially on aircraft forums. Apparently, the conversion coating is not required when using self-etching primer. When I painted the Lightweight, any spots that went to bare metal were cleaned, scuffed & hit with a light coat of self-etching primer before being top-coated.

A few years ago I used self-etching primer on a new quarter panel. Worked like a charm. Everything is holding up swell, with no flaking or problems of any kind.