Q

qiutong

Active Member
Hi everyone,

I've read many posts and websites that say one way to prep aluminum for primer is to use a scotchbrite pad and Dawn dish soap to scuff the surface and clean off all of the surface oils. Ideally, you want to get a "break free" water film, indicating that all oils have been removed. While building the empannage, I did it this way, and it took forever to get that "break free" film I was looking for. Each part seemed to take several scrubbings and about ten minutes each.

Now that I've started the wings, and was faced with many more, and larger parts that need to be prepped for primer, I started looking for a faster way to remove all of the surface oils. I had several chemicals left over from my automobile restoration days, but the best chemical/cleanser I found was "Simple Green". It comes in spray bottles as well as concentrated versions, and can be purchased almost anywhere. It is also environmentally safe and won't harm your skin either. It worked MUCH faster than the "Dawn" did. I still used the scotchbrite pad with it to make sure that the surface was well roughed-up.

I hope that this might help someone else as they prep for primer. If some of you more experienced builders see a problem with this cleaner, please chime in. The primer seemed to lay down very well and seems well adheared to the metal, so at this time it seems okay. Hopefully it will not be a problem down the road. We'll see.

Brad
 
Are you using regular Simple Green or the Extreme, which is formulated for aluminum? I seem to recall that the regular may cause corrosion issues if it isn't totally rinsed out from crevices and such. The Extreme is made for aircraft, according to Simple Green's website.
 
Haven't tried the Extreme for primer prep, but have used it on my plane for general cleaning & it sure does the best job of any product I have found, cleaning stains in a few seconds that nothing else would touch. I expect it would work well for degreasing.

And Rod is right, the regular SG must be thoroughly rinsed or it will cause corrosion.
 
I could remember getting my @xx chewed for using simple green to degrease high performance pistons/jugs. What I was told is that simple green corrodes aluminum.
 
I don't even keep simple green in the garage with the airplane. I keep everything that I can identify as corrosive in a smaller shed on the side of the house.
 
Home Depot sells the good stuff..

And you can purchase the blue bottle Simple Green --- for aviation at
Home Depot. It has the Boeing specs right on the bottle. Might be in a different isle than the regular cleaning product.... though.

We spray it on & then wipe with a well damped rag, followed by another rag.

L.Adamson --- RV6A
 
Although corrosion creation should always be a concern, do note that Brad is talking about prepping individual not-yet-riveted parts. Compare that with prepping an assembled airplane using the acid etch and alodine process, something most of us would consider reasonable. In Brad's case there are no seams to trap cleaner and he is obviously taking care with the water rinse.

I'd want the aluminum-safe Simple Green for wipe on, wipe off cleaning, but with a good water rinse and no seams I'd find it hard to worry about the regular stuff.
 
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What Dan said...

I was just about to say what Dan said. The potentially corrosive properties of Simple Green are probably why it works so well for primer prep.
 
Thanks for the heads-up on the potential corrosion problems of Simple Green. I didn't even know that they made more than one type. I was using the regular home use type. Next time, I will get the type that is formulated for aviation. I was glad to hear that it is also available locally.

When I cleaned my parts they were not assembled, therefore, no seams to trap any residue. The drilled holes could, I guess, hold some, but when I rinsed the parts, I continued to scrub with the scotchbrite pad as the water ran over the part. I can't imagine that any was left on the part.

I will continue to prep for primer with the "aviation" Simple Green, but will be very careful to completely remove all of the cleaner from the parts. If someone has any suggestions that work as well, but without the potential corrosion problems, I'd love to hear them.

Thanks,
Brad
 
qiutong said:
Thanks for the heads-up on the potential corrosion problems of Simple Green. I didn't even know that they made more than one type. I was using the regular home use type. Next time, I will get the type that is formulated for aviation. I was glad to hear that it is also available locally.

When I cleaned my parts they were not assembled, therefore, no seams to trap any residue. The drilled holes could, I guess, hold some, but when I rinsed the parts, I continued to scrub with the scotchbrite pad as the water ran over the part. I can't imagine that any was left on the part.

I will continue to prep for primer with the "aviation" Simple Green, but will be very careful to completely remove all of the cleaner from the parts. If someone has any suggestions that work as well, but without the potential corrosion problems, I'd love to hear them.

Thanks,
Brad
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Coleman lantern fuel (naphtha) is a very good degreaser that doesn't leave a film. Obviously it is flammable, so precautions are in order.
 
I use DX-330. Wipe it on with a paper towel and look at the towel. When it comes back clean, you know you've gotten all of oil off.
 
I just Scotchbrite then clean with a paper towel soaked in acetone. Remember the latex gloves. Works simply and cheaply. A gallon of acetone will last most of the project.
 
Simple green with Boeing Spec or the "other" simple green?

Since this seems to be the most appropriate thread I will try expanding on this here first. Having reviewed as many posts as I can that cover all the possible prep and cleaning options for our aluminum parts, I decided to go out to HD to find the non-corrosive Simple Green product with the blue color and the Boeing Spec "right on the bottle." What I found instead was some purple-colored Simple Green (Simple Green HD, for Heavy Duty) that states that it is also a non-corrosive formula, and good for use on aluminum and other substrates. Apparently the Denver area HD stores do not seem to stock the Boeing-spec version from what I can tell.

So, my question is if anyone has used this other non-corrosive formula, or if there is any feedback on its use as opposed to the one with the Boeing spec on it? One post I read that contained a letter back from the company that makes Simple Green did not even mention the purple stuff at all, so I am naturally curious if this stuff is the same or a similar formula to the blue stuff or not?
 
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Simple Green Aircraft Cleaner

I just checked their website and they say:

Extreme Simple Green
Motorsports Cleaner & Degreaser
Extreme Simple Green? Motorsports is a cleaning and degreasing product that is extremely aggressive on grease and heavy soils, but won?t harm the high end surfaces found on motorsports equipment. This product is effective for use on motorcycles, ATVs, sports cars, RVs, watercraft, bicycles, aftermarket parts & equipment and more! Extreme Simple Green Motorsports meets compliance standards for Boeing spec D6-1748P. Originally developed for the aircraft industry and geared toward safely cleaning high end aircraft exterior and engine surfaces, this product is an ideal choice for all of your motorsports cleaning and degreasing needs.
 
How simple is simple green?

Thanks for replying Bob - yes, if you go to their website and click under the industrial section you find the extreme product you refer to. The stuff I ended up buying is found in their household section, about half way down the page, and is called Simple Green Pro HD (Heavy Duty) - both state that they are non-corrosive.
 
Bob'sRV6A said:
I just checked their website and they say:

Extreme Simple Green
Motorsports Cleaner & Degreaser
Extreme Simple Green? Motorsports is a cleaning and degreasing product that is extremely aggressive on grease and heavy soils, but won?t harm the high end surfaces found on motorsports equipment. This product is effective for use on motorcycles, ATVs, sports cars, RVs, watercraft, bicycles, aftermarket parts & equipment and more! Extreme Simple Green Motorsports meets compliance standards for Boeing spec D6-1748P. Originally developed for the aircraft industry and geared toward safely cleaning high end aircraft exterior and engine surfaces, this product is an ideal choice for all of your motorsports cleaning and degreasing needs.
Click to expand...

Lookie there...says it's perfect for your plane right on the bottle! :)
 
Flyin'Bryan said:
Thanks for replying Bob - yes, if you go to their website and click under the industrial section you find the extreme product you refer to. The stuff I ended up buying is found in their household section, about half way down the page, and is called Simple Green Pro HD (Heavy Duty) - both state that they are non-corrosive.
Click to expand...

I bought the purple stuff too, but didn't use it. Usually, the aviation type isn't in the household section. Check around the tool area, or end isles.

L.Adamson --- RV6A
 
"Ideally, you want to get a "break free" water film, indicating that all oils have been removed. While building the empannage, I did it this way, and it took forever to get that "break free" film I was looking for. Each part seemed to take several scrubbings and about ten minutes each."

Alumiprep after detergent washing will pass the water break test with much less effort.
 
Alumiprep corrosive...

I use Alumiprep, which I think is designed as a cleaner/etcher for aluminum. I believe that it is corrosive. If you leave a part in too long then it starts to turn black. But if you leave it in for the appropriate amount of time and then rinse thoroughly it cleans the surface without corroding the parts.
 
No simple Green for me yet, but sometime.

I am still priming all my parts before riveting. Then I use Azko Noble Zinc Chromate Wash Primer. The rep told be to use powdered calgonite in warm water. Less if the metal is fairly clean to start with, more if its not.

I use gray 7448 scotchbrite for cleaning almost all of the sheet metal parts and the maroon 7447 for the bars and extrusions to get them really clean.

Rinse very well, and then blow dry with clean compressed air while parts are suspended on safety wire.

Leave them hanging and knowing that they are fully dry, prime them.

Don't touch them until the primer cures at least a hour or two.

Note: If you are going to put anything over the primer you have 4-6 hours that it is chemically open.

When in doubt follow instructions.

Other than one little trick that I do that is NOT in the instructions, and that is I thin the green primer mixture about 10-15% with medium laquer thinner for a lighter smoother coat.

I am saving simple green for once I get er flying and need to keep the smudges of my baby's belly.:p
 
Found the bottle of the blue stuff on clearance

Thanks for the responses everyone. So I stopped by Home Depot after work and went looking on the end caps as one of you suggested, and found one lonely bottle of the blue stuff sitting in the auto clearance section for about $2.60. I am totally on board with performing the water sheet test, regardless of the cleaning solution I use. Interesting comments about alumiprep as well.

So now I have some blue stuff and some purple stuff that is non-corrosive, and all with the name "green" in the product name, just to keep us all confused I guess. I will try these out on some smaller parts or even on some scrap and see how well my elbow grease holds up.

Judging from how much work it took to debur the underside of my spar flanges to my satisfaction, (I used the scotch brite pad, since I could not get my deburring tool to fit in between the flanges to reach some of the holes), I may opt for one of the other "less laborious" cleaning options for the larger pieces.
 
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I am totally on board with performing the water sheet test,
Click to expand...

I would be VERY cautious using either form of Simple Green as a cleaner and prep for priming.

One of the characteristics of both simple greens is that they are surfactants http://chemistry.about.com/od/chemistryglossary/g/surfactant.htm

That is when mixed with water they will cause it to spread (sheet).

While still wet you may think you have a well prepped surface only to later find that you have a thin residue of the extreme.

I use Simple Green extreme to clean the T 28 (it is the only thing that works) Looks great wet (meaning the water sheets and covers all) but depending on the concentration I use it can take HOURS to rinse off all of the residue. You cannot always see the residue, often the only indication of its presence is a slight foaming when you blast it with high pressure.

Simple Green may be a cheaper method of cleaning but I would not use it to prep for primer.
 
woes of cleaning metal....

Thanks Milt. I know exactly what you refer to regarding the film/residue. Perhaps I have made a false assumption that because it has the Boeing spec it should be OK for primer prep cleaning. I don't want to have to go out and buy a pressure washer to be sure I got it all off either.:)

If not Simple green for primer prep cleaning then that leaves me with the following list of options I guess:

Powdered calgonite
PPG products
Dawn dishwashing soap (but which version of that, gheeeesh!)
lacquer thinner
acetone
alumiprep
90% rubbing alcohol
coleman fuel

....and I'm sure I am leaving some others out. I know alumiprep is a popular choice for those applying alodine and epoxy primers, but I made a decision to use self etching primer (not 7220 spray can, but the expensive kind I have to mix), at least on the tail sections, so I don't think I want to double etch the surface unnecessarily by using both alumiprep and the SE primer. Please, no primer war discussions - I have read all the primer posts, done my own research, made my decision, etc.

I wonder if spit shine is corrosive? :D
 
Alumiprep - Yes, acid is corrosive. But, alumiprep on the surface for 90 seconds followed by a fresh water rinse is not and you will see the water sheet off that piece of metal beautifully. Light acids can be used to our benefit in metal prep.

My process was: Laquer Thinner clean, detergent wash with scotchbrite scuff, alumiprep immersion or brush on for 90 seconds, fresh water rinse, air dry, prime.

Flying for 425+ hours and nothing has fallen off....yet.
 
bsacks05 said:
My process was: Laquer Thinner clean, detergent wash with scotchbrite scuff, alumiprep immersion or brush on for 90 seconds, fresh water rinse, air dry, prime.
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Bruce (and others),

I am just starting, so my question is out of ignorance.

Why did you use lacquer thinner before the soapy scotchbrite step?

(I was planning to soapy scotchbrite, then rinse, lacquer thinner (or acetone?), then alumiprep and rinse (not positive yet), air dry, then prime.

I thought the lacquer thinner was to remove the oils left on the part during scotchbriting with my oily hands.

Again, I haven't started yet, so I am looking for some guidance before settling on a best practice.
 
Andrew,
I used LT (with gloves) first in order to remove oils, sharpie, and anything else. Also, adhesives from tape, part number labels, etc come off easily with LT or acetone. Then I proceeded with the other steps.
That is the process I used, but of course there are quite a few variations as you can see. Just pick what you feel comfortable with because you will be doing it over and over and over throughout your build.
 
Will try some solvent-based solutions I guess

Since I am familiar with acetone and how well it cleans the aluminum on my RC engines, I guess I will try that, since it is "readily" available on the garage shelf. I also know from experience that the alcohol does a great job removing the ink that is stamped on the parts.

I read another post in here some time ago that mentioned that LT does not remove the grime, but just moves it around or spreads it out. Not sure if that's true or not, but I am willing to side with those that have used it and are now flying without any problems with primer or paint.

At any rate, as you have stated - pick something and go with it. I refuse to let cleaning and primer prep bog down the build any more than it already has... I will save the Simple Green for later.

Thanks again for eveyone's input.
 
turbo super rv-10 said:
soap is a release agent
i would use aluimi prep
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In my experience, scrubbing parts with a scotchbrite pad and Dawn/water mixture is good primer prep, at least for variprime and NAPA 7220. Dawn is a degreaser, and the scotchbrite mechanically removes any oxide film. Dawn is water soluble and goes away in the rinse. I sure wouln't use this same method to prepare aluminum for fiberglass I ever wanted to remove.:rolleyes:
 
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