Michael Burbidge

Michael Burbidge

Well Known Member
I found a product called prep-n-etch at Home Depot. It is a metal cleaner meant for prepping metals, including aluminum, for painting. It is phosphate based. Has anyone tried it? Would it be appropriate before priming aluminum airplane parts?
 
Not sure I can answer the real question, but if it is phosphate based, it is probably phosphoric acid, which typically will help dissolve (iron) rust. Not sure what it will do to aluminum or aluminum alloys. Partly would depend on what else is in there, based on what I know of chemistry.

greg
 
Acid...

Greg Arehart said:
Not sure I can answer the real question, but if it is phosphate based, it is probably phosphoric acid, which typically will help dissolve (iron) rust. Not sure what it will do to aluminum or aluminum alloys. Partly would depend on what else is in there, based on what I know of chemistry.

greg
Click to expand...

Greg.. It appears that phosphoric acid is the main active ingredient in Alumiprep 33

http://www.jamestowndistributors.com/userportal/pdfs/MSDS/Awlgrip/alumprep33.doc

But why risk the Home Depot stuff? You can buy acid etch that meets aluminum acid etch/alodine requirements at your local auto paint store... and no hazardous shipping charges...:)

gil A
 
acid etch

Phosphuric acid is also the active chemical in Variprime to etch the metal.

Regards...Chris
 
You can also purchase all of the blind rivets you need at Home Depot. This will probably save you more money than the etch. Like the phosphoric acid, all you need to know is that they are aluminum. Please, unless you have a great deal more info on the paint, stick to aircraft grade material. You've invested a lot of time and money to this point. Why would you want to risk all of this work?
If you want to see the ultimate in money saving, look at the post where builders are hand threading their gear legs. After literally chiseling the thread form onto the heat treated shaft with a constantly dulling die, no one seems to care that they have likely generated a significant number of tears and cracks which may eventually lead to fracture. If the nut fits, good enough. Save money? Yup!
Terry
 
Just to clarify..

terrykohler said:
You can also purchase all of the blind rivets you need at Home Depot.
Click to expand...
Terry,
I assume that this comment is "tongue-in-cheek."
But before some "newby" runs out to Home Depot to buy pop rivets, let me say that any blind rivets used in aircraft NEED to meet some kind of "specification!" The ones at Home Depot don't!
 
Ordered Alumiprep...

Sorry for asking the question. You guys are right, it is stupid to get this kind of stuff at Home Depot, when you're not sure it will work just to save a few bucks. I couldn't find Alumiprep locally so I ordered some. That and Alodine.
 
No, not necessarily so. I am sure product is product. The question is, what is the product.

Each brand is it's own "chemical soup". I can't believe there are that many soups out there to choose from.

I got the stuff from West Marine in the (2 ounce?) bottles. It APPEARS to be Aluma Prep and Alodine. It is SUPPOSED to prep and convert aluminum. It looks and feels like AP 33 and Alodine. I don't use much of it and for my needs, it should be fine.

It may suit you too?

:confused: CJ
 
Apples, apples and oranges

Captain_John said:
No, not necessarily so. I am sure product is product. The question is, what is the product.

Each brand is it's own "chemical soup". I can't believe there are that many soups out there to choose from.

I got the stuff from West Marine in the (2 ounce?) bottles. It APPEARS to be Aluma Prep and Alodine. It is SUPPOSED to prep and convert aluminum. It looks and feels like AP 33 and Alodine. I don't use much of it and for my needs, it should be fine.

It may suit you too?

:confused: CJ
Click to expand...


Captain... not quite apples to apples..

If it's this stuff from West Marine... yes it is probably the usual acid etch/alodine treatment (two steps) for aluminum.

09186_f.jpg


However, the original poster was talking about some generic (try a Google search "prep-n-etch", all I came up with was a concrete etch) hardware store stuff that is for all metals, and is one step.

Not quite the same thing.

gil A
 
"Wheel Brite" is a product at auto cleanup suppliers that works like the Alumprep.


makes alum shine like new money


cary
 
Not the same acids

caryr said:
"Wheel Brite" is a product at auto cleanup suppliers that works like the Alumprep.


makes alum shine like new money


cary
Click to expand...

Not exacty the same....

The MSDS

http://www.mvpdistributing.com/pdf_mvp/24-44_wheel_brite.pdf

..states the Wheel Brite has Sulphuric Acid and Hydrofluoric Acid in it as well as the Phosphoric Acid of the "aircraft quality" acid etch.

Does it make a difference? ... I don't know...
But the real stuff is easy to get, is tested for our application, and is not very expensive....
Why bother with the unknown stuff?

Parts may be parts - but acids are not all equal....:)

gil A
 
HF warning

I don't know what the concentration of HF (hydrofluoric acid) is in any of this stuff, but it is extremely dangerous to humans. Although HF is a weak acid, in invades tissue and reacts with bone material. Although probably not permanent, it can be EXTREMELY PAINFUL for days to weeks if you get a bad burn. I know because I use it in my lab to dissolve rocks! (it's also the stuff that's used to etch glass) The HF itself, being a weak acid, is not very noticeable when you contact it, in comparison to sulfuric which is pretty obvious shortly after coming in contact as you get an acid burn. If/when I use HF, I always do so with new rubber gloves, and in a chemical hood. Granted, I am using the highly concentrated stuff and don't want to breathe the vapors. The "consumer" stuff that is off-the-shelf is (must be?) pretty low grade (otherwise they couldn't put it on the market as they do) and it is doubtful that you will have an issue with vapor. But if it were me, I would still definitely use rubber gloves.

greg
 
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