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I am at that stage where I am prepping for paint. I have heard many mixed stories of which products are suitable for the job.
An aircraft spray painter that I recently met has recommended that I scour using alumiprep, rinse, spray on alodine, rinse and dry, wax and grease remover and then paint.
Another friend of mine prepped his Savanah by scouring with water, scour with alumiprep, wax and grease remover and then paint.
Yet another method that another friend of mine has used is to scour with denatured alcohol (metylated spirits) and then paint.
Obviously the objective is to remove the oxide layer on the metal and paint it as soon as possible and I have just read that denatured alcohol does that very job so why use nasty chemicals like alumiprep. As any wash from the painting process floods to the ground just outside my shed, there is no way that I am going to use alodine and contaminate the ground with chromium where my son plays.
I have already purchased some alumiprep but I am concerned with what might happen if trace amounts of it get caught in crevices inside the structures. On the other end of the scale, I have an aquaintance that has a 601 HD that is painted and unflown and has been in a shed all of its life. It has bubbly corrosion on the metal pushing the paint up. I have no idea what prep work that he did.
So, is denatured alcohol enough to stop corrosion on a project that is 3 years old? I am thinking that it might be and as a final wash, it certainly dries nice and quick when compared to water. This means that I can get my epoxy primer on very soon after prepping instead of hours down the track.
What have you used to prep the aluminium on your plane? What other toughts do you have on the topic?
Hey Phill, check out this site http://www.stewartsystems.aero/default.aspx
I'll pass on some advice from experienced builders I have met over the years, these guys have built over 40 airplanes. They're building RV's now, 2 or 3 a year. Wait at least a year before painting the airplane, not including the fiberglass. The DAR gave the same advice after inspecting my airplane. At minimum, wait until you do your Weight & Balance before painting.
6061 Aluminum is corrosion resistant and can be polished. The link listed offers some products that might be useful, just in case.http://www.stewartsystems.aero/catalog/3afff6e7-8eea-4019-840d-f362...
Stewart Systems has a series of five videos on youtube:
just paint the bloody thing
Like you I wanted to avoid alodine etc for obvious reasons. What I did stumble upon at my local aviall was a product called PreKote surface pretreatment. I've been using it to prepare all my parts before painting and it seem to work great. The whole process is very easy all you do is spray it on the part with a normal household spray bottle then scrub the surface down with scotchbrite. You then wait a minute do the same thing again then rinse it off with water and let it dry. It foams up like soap when you scotchbrite the aluminium and looks as though it turns the aluminium oxide black like when you use rust convertor on steel. Haven't had any parts sitting round long enough to know what it's like long term but they say in there promo that the us airforce now uses it so I figure it must work quite well. It was about $60 to $70 dollars for the kit which included a 1 gallon/3.8 litre bottle which looks to be enough to do a whole aircraft. The mob that produce it are called pantheonchemical who have a website pantheonchemical.com.
How has the PreKote worked out. Is your paint adhering?
And what primer and paint did you end up using?
I will assume that we are prepping 6061 T-6 alu. the right way would be to etch with alodine 1200S red scotchbrite and water to get your water breakfree surface, apply alodine. let dwell to a light gold tone. rinse throually. NOTE: its much better to do this process on parts prior to assembly to avoid alodine becoming trapped in areas where you cannot reach to rinse.
just prior to prime, a wiping with .a light solvent isopropal alchol is fine....lightly tack than prime. best to use a good two part epoxy polimide primer most need to be top coated with paint within 8 hrs of priming..
If assembled and you have to alodine a one step alodine can be used.
google na-01-1a-509 its the navy's aircraft corrosion control bible
The first method you mention here is similar to that a friend of mine used on his RV7, but he said scour with methylated spirits. He carted his RV off to an automotive spray painter and they used a two pack.
A paint seller I questioned advocated the Alodine, citing that's what RV builders do, but remember, they are built with 2024, which is Alclad, different to the 6061 we are using.