Priming/Painting aluminum tube?

Hi,
I will be receiving a 7 1/8" OD .083 X 40" formed and welded aluminum tube from a local fabricator for my 6"f6 home made scope, to replace my old home-made fiberglass tube.
I want to paint the inside with Krylon Ultra-flat Black #1602 paint and the outside with another Krylon Paint, probably a high gloss white.
I do wish to ensure the best bonding, and Preston Engebretson had recommended a Phosphoric Acid wash, then a primer.
I have some Phosphoric Acid used to wash Teak, as part of a Teak Cleaner with a separate Sodium Hyroxide rinse - will that Acid be OK?
WHAT PRIMER should I use for these products?

I have painted aluminum in the past and was NEVER totally successful. They peeled and flaked, usually.

All help from successful aluminum painters would be appreciated.
Also, if anyone could get Preston Engebretson to drop an e-mail to me at [email protected], that would also be good.
Thanks all.
Mike.....>

Mike...check your email...also, I've used the product that Don
mentioned...it works quite well.

Regards Preston

You might also give this a try:

http://www.rustoleum.com/product.asp?frm_product_id=29&SBL=1

I have used it. As I recall it is close to Celestron Orange but a bit darker on color. Worked very well for me.

I suggest you give some consideration to leaving it unpainted. An unpainted aluminum tube has better thermal characteristics (low emissivity), and you don't have to worry about scratching your fine paint job. You can give it a "jeweled" finish, which is simply overlapping circular swirls added with steel wool or a sanding disk. It is fairly easy to do with a simple jig.

A friend has been building Newts and trying various tubes for three decades, and he wouldn't use anything other than unpainted aluminum lined with flocking.

Clear skies, Alan

I had my scope painted by an aircraft painter. He did an alodine conversion coating first, then epoxy primer, followed by urethane paint. It's the same system he uses on aluminum aircraft and helicopters, so you can imagine the flexing and vibration encountered in those applications.

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Hi Mike. I received a 50 inch by 16" id x 1/8" thick tube from the fabricator. I had them ground the weld off and fill in pin holes along the weld by spot welding. I then used a crafstman 3d sander to smooth out the weld. I called around town to find a small powdercoating shop that did runs of white on other products. For $30.00 the tube was sand blasted and powdercoated a brilliant white. below is the before picture. and I will post the after picture on the next post.

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