Painting aluminum roof flashing?

[Aaronw]

My plans on making a truck tanker from ABS are not working as planned. I saw this roof flashing at Home Depot which seems like it might be a good possibility.

I'll probably build some interior support from wood or plastic.

http://www.homedepot.com/p/Construction-Metals-Inc-10-in-x-10-ft-Aluminum-Valley-Flashing-RV1010A/202092846?N=5yc1vZas6d

A good wash and priimer is a given, but I thought I'd see if anyone has used this stuff before and found any issues I should watch out for.

It is a nice thin gauge aluminum, so I am assuming I'm not the first to notice this stuff and thought it might make a good modelling material.

Thanks

[impcon]

http://www.the-coatings-expert.com/painting/aluminum.html

[fatkidd]

if you are going to paint over aluminum, here's a few tips...

Be sure to wipe down the aluminum with lacquer thinner to clean any impurities off of the aluminum. (old school method was to wipe metal down with white vinegar just before painting as "tack rag" and the vinegar etches the metal a little)

Use a "self etching primer" for your first coat and be sure to do it in light coats.

Let the etching primer dry thoroughly, spray your "regular" primer over the etching primer, and wet sand before spraying your base coat.

Be sure that you do not sand through the etch primer.

Hope this helps

[Aaronw]

Thanks, I wouldn't have thought of the etching primer.

Gary your link doesn't work. I tried a couple of fixes but couldn't get anything to come up, even googled the coatings expert but got nothing.

[Harry P.]

Wouldn't thin sheet styrene formed around circular bulkheads be a lot easier than working with sheet aluminum? I know it would be for me...

[fatkidd]

Wouldn't thin sheet styrene formed around circular bulkheads be a lot easier than working with sheet aluminum? I know it would be for me...

How does this help the OP's question?

[Harry P.]

How does this help the OP's question?

By suggesting an easier way to do it instead of using aluminum.

[Aaronw]

I don't think so, really thin styrene would be flimsy, something stout enough to hold up won't flex that well without some heat. The aluminum flashing is very bendable, but stiffer than thin styrene. I've had some good luck shaping brass and aluminum in the past, but nothing on quite so large a scale.

It was $13 for 10 feet, so not much of a risk and I can always use it for doing repairs on my house. I've got a few ideas for shaping it, will have to see how it works out.

No harm in asking the question, it was a fair suggestion. This is all experimentation at this point, ideas are always welcome.

[Psychographic]

As said already, etching primer is the way to go.

As a side note, have you tried looking into diecast models for a tank, or the one from the Lil' Gasser Showrod?

Edited March 25, 2014 by Psychographic

[oldnslow]

Wouldn't annealing the aluminum make it easier to work with?

[Aaronw]

I've actually got a couple of model tanks that could be used, but I've got a couple of potential projects in mind and really want to figure out a way to fabricate my own tanks. I've got a couple of idea floating around my head based on this aluminum.

Robert, possibly, but it is already pretty flexible so I don't think that is going to be much of an issue.

[Ace-Garageguy]

I'm 98% certain that any aluminum flashing you'll encounter is already clear anodized. Bare aluminum would oxidize almost immediately otherwise, so the recommendations for prepping bare alloy do not apply here. Here's an excerpt from a knowledgeable source...

"Anodizing is the best possible surface for paint adhesion. No special primers or anything like that normally associated with painting aluminum is required. Bare aluminum is highly reactive with air. It doesn't matter what you do to get the surface bare, chemically or mechanically, because it immediately begins to reform oxide to protect itself. An anodized surface is non-reactive, or inert, in atmospheric exposure. That's why its appearance stays substantially the same over time. Because it is inert there's no need to apply any chemical or primer whose purpose is to convert the surface from reactive to inert. Also, the method of "growth" of the anodized surface leaves it somewhat porous on a microscopic basis, so it has ideal properties for letting the paint "grip" the surface. As an example of how well anodized aluminum holds paint, all pre-painted architectural sheet aluminum is first anodized and then painted with no primer of any kind between the surface and the topcoat. You can typically take a piece of this painted sheet, bend it in a brake, and fold it flat on itself like a hemmed edge, and the paint will remain intact.

Try a piece and see for yourself. The same paint that will almost peel off bare aluminum in sheets will have to be blasted or sanded off an anodized surface."

FULL THREAD HERE: http://www.practicalmachinist.com/vb/general/paint-adhesion-anodized-aluminum-157007/

Remember, WHEN IN DOUBT, TEST FIRST.