How To Finish Aluminum In The Garage?

[dogma]

I have a small, unimportant, aluminum part that I would like to cosmetically protect against being splashed with cutting fluid. The part is in no way critical but I would like to go about this the "right way" as a learning excise. I have no previous experience with finishing aluminum and I am not particular about the type of top coat. From what I have read, aluminum requires more consideration than the mild steel I am used to dealing with. However, my garage is not yet a super fund site and I would prefer it to stay that way.

Options that I have identified.

• powder coating - it seems that this may be acceptable to apply to bare metal aluminum? I do not have powder coating equipment but this seems doable on a small scale. The primary health hazard is inhalation of fine dust. Of course, for a one-off I would have a local finisher do it.
• enamel, epoxy, urethane, etc. top coats - it sounds like all of these need to be applied over "primed" surface that has been anodized or chromate converted (alodized)?
• ceramic coatings - do these need a conversion surface prep? Media blasting seems to be recommended. I don't currently have a blast cabinet or a high CFM compressor to drive one. They mostly (all?) seem to use MEK as a thinning agent. I'm not thrilled about spraying high concentration MEK but this is tolerable with a respirator and bunny suit.
  
• anodizing - toxicity isn't bad but I'm not thrilled about the potential for acid bath fumes to cause corrosion. My main hesitation is needing to store the bath chemicals.
• chromate conversion (alodizing) - not exactly thrilled about handling potentially hexavalent chromium... I looked at a few SDS' and they pretty much only list chromic acid but this is probably in the strong NO WAY category.
• aluminum one step primers - these reportedly don't yield great results. I'm not sure how well they could work as the SDS seem to be mostly solvents and titanium dioxide and/or zinc phosphate. Eg. http://www.rustoleum.com/MSDS/ENGLISH/254170.pdf

Are acid etching primers commonly used with aluminum? What do you folks recommend?

 

[Firestopper]

Your inquiry is a little ambiguous. What are you protecting the aluminum part from? If your looking to simply paint the part, it must be clean like any other paint prep, however a special primer should be considered for aluminum. Zinc Chromate primer is what I use when spraying aluminum. You should be able to find a spray can of it locally if you only need to coat a small part. Use in a well ventilated area as with all paints and solvents and protect your respiratory system. Keep your lungs pink.....

 

[TOOLMASTER]

clear lacquer

 

[jpfabricator]

The powdercoating is fairly cheap and most semi major citys have a powdercoater or 2, but it adds irregular thickness to your part.
The 2 part epoxies, paint, duracoat, ceracote, are all epoxies that will stick to clean scuffed surfaces. They arent the best for abrasive protection but are fairly cheap and doable at home.
I cant coment on the anodizing, as I have never tried it.

Sent from somewhere in East Texas by Jake Parker!

 

[Bob Korves]

Why are you not just leaving the natural aluminum finish and let the cutting fluid help preserve it?

 

[dlane]

I powder coat Smalls often , what is it ?.

 

[Billh50]

I would just buy a spray can of clear and paint it.

 

[dogma]

What are you protecting the aluminum part from?

[water soluble] cutting fluid. I believe that is commonly some composition of water, petroleum distillates, a surfactant (eg., triethanolamine), and/or a glycol.

Zinc Chromate primer is what I use when spraying aluminum.

I hadn't discovered that class of treatments. Sounds like a combination of cold zinc plating and chromate conversion in a can. I pulled an SDS and it did list chromic acid, which means Cr(VI) is a concern.

 

[dogma]

clear lacquer

I thought lacquer would be removed by surfactants?

 

[dogma]

The 2 part epoxies, paint, duracoat, ceracote, are all epoxies that will stick to clean scuffed surfaces.

I suspect your right that an epoxy is the most practical / reasonable toxicity home option. I even found some rattle can options. The pot times are at best a few days, so it would mean burning an entire $20 can for a small part.

The powdercoating is fairly cheap and most semi major citys have a powdercoater or 2, but it adds irregular thickness to your part.

I think I will go ahead and try to price powdercoating to see what the proccess is like.