Blasting Aluminum

major519

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Nipissing, Ontario, CA
I have recently aquired a M274A5 mule.
It needs to be stripped of paint to bare aluminum.
What are my best solutions for doing this?
I have used sandblast in the past on steel but knw it is very agressive on aluminum.
Should I be looking at soda blast or is sandblast OK with the correct sized media?
I know some guys use glass bead on aluminum as well but for an entire mule this is not feasible.
 

JCKnife

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Kentucky
Tag with interest. I was wondering how to clean up winch bodies before re-painting (they are aluminum also).
 

3dAngus

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Soda blast or crushed walnut shells. They prefer the crushed walnut shells. Comes out shiny and clean, polished surface.
Reference: History channels "American Restorations"

It will not damage aluminum or give it the grainy characteristics sand might. Gentle.
 

3dAngus

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With a chem stripper, you would need to dip in a acid bath at a commercial location with the tools for recovery. It is to big for chem bath for the DIYer and would be a huge environmental hazard. The aircraft refurbishers have the solution with a recovery process on hand, but if you could get access, it would definitely be the way to go. It's not cheap. Crushed walnut cost about the same as quality sand, and is not cheap either, but not a hazard either.
 

rickf

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The problem with chemicals is neutralizing them afterwards. You will never get it all and corrosion will soon follow. I would go with the walnut shells also. What you don't get could be lightly sanded and painted over. You will need ti lightly sand the whole thing anyway to make the paint stick.

Rick
 

JCKnife

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I'm having good luck with paint stripper from Lowes. It's a slow process: apply, wait, scrape, wire-brush. But it's doing the job.
 
Paint removal

I have recently aquired a M274A5 mule.
It needs to be stripped of paint to bare aluminum.
What are my best solutions for doing this?
I have used sandblast in the past on steel but knw it is very agressive on aluminum.
Should I be looking at soda blast or is sandblast OK with the correct sized media?
I know some guys use glass bead on aluminum as well but for an entire mule this is not feasible.
I have not done a lot of paint removal. That said a friend that does this for a living uses "Aircraft coating remover". I tried it and it really gets the job done... now. 2cents2cents
 

hndrsonj

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I'm having good luck with paint stripper from Lowes. It's a slow process: apply, wait, scrape, wire-brush. But it's doing the job.
Also, most of the newer stuff is neutralized with water. It makes it alot easier.:beer:
 

JCKnife

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Kentucky
You need to use aluminum primer also, regular primer will not work properly.:driver:
Right. I was planning on using a self-etching primer from NAPA. We've used it often on aluminum-based vent pipe flashings in our roofing installations. The Dupli-color green cap stuff has worked best.
 

135gmc

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Find a shop that does blasting for car restorers. Odds are that they will use soda blasting or CO2 blasting. Walnut shells work if you are in a cabinet-type blaster, but whole vehicle blasting is usually soda blast. They even use it stripping airplanes.

Paint stripper (aircraft-type) would work, but it will be very slow, plus the stripper isn't free. Soda blasting is clean & simple.
 
A

A/C Cages

Guest
Never use stripper if there are seams where it can seep into.
We used on our helicopter soda blasting only but on our rotor blades we used only chemical strippers and then made sure it was free of all chemicals and also oils by using MEK and had to have a complete water break on them.

If you are wanting to remove paint from T6061 under 1/4" thick, never use walnut. Tends to overheat them and you can get warp from it. We found out this the most expensive and hard way. Had to replace all the header panels in the S76. Ouch $$$
 

greybird

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I have spend a lot of time dealing with thin aircraft aluminum. I don''t know how thick your aluminum is on the mule, but here are several suggestions.

1. Patience. Aluminum is easy to destroy.

2. _NEVER_ use steel or stainless steel wire brushes. They will tiny pieces of steel imbedded in the aluminum, which will corrode later. A wire brush in a drill or grinder will eat your aluminum, and leave a BADLY distorted surface. ( you will understand after you try it)
Scotch - brite at slow speeds is your best corrosion remover.

3. Tal-Strip brand paint stripper (sometimes called "Aircraft Stripper" works well for removing paint, but must be rinsed _THOROUGHLY_. I can find it at my local auto parts store. Use serious chemical resistant gloves, goggles, use it outdoors, etc. It is NASTY STUFF. If you get it on your skin, the burning pain will help you find the spots quickly. Getting it in your eyes will mean a trip to the hospital or worse. Not something you want to wash into your sewers either.

4. A company called Aircraft Spruce ( and others ) sell stuff called Aluma-Prep, and Alodine. The Aluma-Prep is a mild acid that cleanes the aluminum before painting. The Alodine ( which contains Chromate, not something you want to get on you of spill into your sewers ) will make the surface of cleaned aluminum less likely to corrode. With good primer, you may not need it in Canada). If you use this stuff, use it carefully, and follow instructions. Dumping it into your sewer will not make you popular with your local environmental officials. Dispose of waste properly.

5. Aluminum is resistant to _MILD_ Acids. Caustic or basic materials ( found in some paint strippers ) will turn your aluminum into expensive white powder. Engine cleaner and even Simple Green contain enough caustic to start the corrosion process. ( Simple Green now makes an aluminum safe cleaner )

6. If there is an Airport around that services small planes, (or large ones for that matter) Call the repair shop and ask an A&P mechanic for advice. they deal with aluminum and corrosion all the time. An Aircraft paint shop would be a treasure trove of knowledge.

7. Sandblasting: Walnut shells are a wonderful thing if you can find and afford them. otherwise, sand, (or a non-silica abrasive) at a pressure of not more than 50 PSI may work. much higher than 50 PSI will cause aluminum sheet metal to heat from the blasting and become wavy. There is not good fix when that happens. ( Don't ask me how I know ) I suspect even Walnut shells could cause the heating and distortion at high enough pressure. There was a while that some places were using Dry Ice as a blast medium to avoid that problem. Remember Item No. 1 above.

8. Be glad you don't live in Florida where Salt Air and high humidity can really eat through Aluminum.

9. Advice given here is worth exactly what you pay for it. Caveat Emptor.
 

JCKnife

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Kentucky
I've been scraping with a putty knife and following up with a wire brush by hand, not seeing any ill effects so far. And I already used a wire brush in a drill on the other end before I tried the stripper. The parts I'm working on aren't exactly free of marks to begin with.
 
A

A/C Cages

Guest
I've been scraping with a putty knife and following up with a wire brush by hand, not seeing any ill effects so far. And I already used a wire brush in a drill on the other end before I tried the stripper. The parts I'm working on aren't exactly free of marks to begin with.

I read that and I was cringing worse then fingernails on a chaulkboard.
Scraper
Wire brush
Drill
Im sure others with aircraft knowledge like myself are all going noooooooo noooooooo nooooooo ...lol

But I guess there is a difference between a multi millon $$$ aircraft and a old MV??
 

JCKnife

Active member
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Location
Kentucky
Right--I'm working on 40-year-old winch bodies that are already dinged up, scratched, etc. Plus they had 2-4 different colors (layers) of paint showing. They will look a lot better when I'm done, I feel confident, and no worse for wear. (obviously I have no reason to scrape on sensitive areas like where seals and gaskets go).
 
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