Alodine, still need to primer?

zx6rrider · #1 01-02-2010, 08:42 PM

Just trying to figure out which way to go here. Im 24 and recently picked up an abandoned tail kit. I was thinking about etching/alodining everything. The alodine is supposed to protect from corrsion so is there any real point to priming anything that wont be out in the weather? Would like to keep it as light as possible so thought the lack of primer may save a pound or two plus some time and money. If I were to lose my medical around 70 and die flying around 90, thats 66 years Id like to see the thing last (OK maybe I'm a little optimistic), do you think the alodine alone would be enough? Going to try and get my hands on some powder so it will be affordable. Looking at the Iridite 14-2, does it matter what I use to etch with, I thought most alodines were an etch/alodine system but I havnt seen what is recommended with the Iridite. Thanks for your advise.

GAHco · #2 01-02-2010, 10:05 PM

The first step is Cleaning the aluminum thoroughly, the next step is a thorough rinse with clean clear water as mineral free as possible.

The second is air drying and not re-contaminating.

The third could be either a) Alodine, or b) Wash Primer.

If you chose a) Alodine, it is better than nothing but should at least get a coat of primer on it for the interior. If exterior use a top coat too .

If you chose b) Wash Primer, (I use US Paints/Azko Nobel) then for interior structure all you have to do is put the wash primer on.

If you chose b) Wash Primer, and are doing a top coat, you will need to epoxy prime, and then add the top coat.

PPG, Azko Nobel, and Sherwin Williams all offer comparable processes.
Some are easier than others but all of these and maybe more have proven results when ALL the directions (process's) are followed.

Research, and ask around what other experiences are, and always remember, painting a whole airplane inside and out is a large and tedious task, it can also be rewarding. Best wishes,

zx6rrider · #3 01-03-2010, 06:37 AM

Thanks for the info, looks like its time for some more research.
And thanks for the hardware book, looks like that will be a great tool along the way

chaskuss · #4 01-03-2010, 08:35 AM

Chad,
I would strongly advise you to use the SEARCH function on the forum. Simply enter the word Alodine into the search box. You will find tons of info in the archives. The SEARCH button is found on the blue bar at the top of this page.
Charlie Kuss

Jim Percy · #5 01-03-2010, 09:39 AM

FWIW, I used brush-on or dip alumiprep and alodine for all of the non-alclad parts, and did not use primer on top. I figured this gave at least as much protection as the wash primer used by the quick-build factory. No sign of corrosion yet, but I've only been flying for ~3 years. Time will tell.

terrykohler · #6 01-03-2010, 10:03 AM

When I started my build in early '02, I set up a corrosion test/comparison of bare aluminum (wrought angle),non-alclad sheet, and alclad sheet.
Samples were tested bare, as well as with alodine conversion, and finally with alodine +zinc chromate.
Testing was carried out in a salt spray cabinet according to ASTM B117
As a result of this testing, I decided to:
1. Alodine and coat all wrought product (you may wish to use something other than zinc chromate)
2. alodine non-alclad sheet (ribs, for example)
3. Paint contact surfaces (for example, between rib flanges and wing skin).
My best guess is that the structure should be good for 100+ years. Just a SWAG based on my own testing.
Terry

Mel · #7 01-03-2010, 10:14 AM

Quote:

Originally Posted by terrykohler

2. alodine non-alclad sheet (ribs, for example)

Just as information; the ribs, and all other 2024 sheet aluminum in the RV kits are al-clad.

zx6rrider · #8 01-04-2010, 03:48 AM

Thanks for all the info, Ive been looking through the archives here for the past couple weeks and noticed everyone primed over the alodine so that was my main question. After reading about primers on here for about 3 hours yesterday, Im half tempted to just scuff and epoxy prime everything and forget the etch/alodine but Im sure after a few more hours of reading I will change my mind again. Hate to say Im trying to be cheap, but if I can get away with just doing one or the other and have it last, I probably will as this is going to be a budget build. Thanks again

chaskuss · #9 01-04-2010, 05:32 AM

Quote:

Originally Posted by zx6rrider

Thanks for all the info, Ive been looking through the archives here for the past couple weeks and noticed everyone primed over the Alodine so that was my main question. After reading about primers on here for about 3 hours yesterday, I'm half tempted to just scuff and epoxy prime everything and forget the etch/Alodine but I'm sure after a few more hours of reading I will change my mind again. Hate to say I'm trying to be cheap, but if I can get away with just doing one or the other and have it last, I probably will as this is going to be a budget build. Thanks again

Another excellent online resource is EAA Chapter 1000's web site. They have extensive info on corrosion control for aircraft. EAA Chapter 1000's membership contains folks who work at Edwards Airforce base. Lots of folks with advanced degrees in aviation related subjects. [In other words, a lot of knowledge there]
See

http://www.eaa1000.av.org/technicl/c...on/corridx.htm

The extent of corrosion prevention will depend on where you live [dry or humid], your mission and where you intend to fly. Living in New Mexico is good, flying 500 feet above the coastal shore line anywhere in the southern States is bad.
Also consider how difficult future corrosion repairs would be. Empennage parts are cheap and relatively easy to build, so a corroded rudder would not be as bad as internal wing corrosion. Future repairs of interior wing corrosion would be the hardest to repair, so that is where you should do the most corrosion control. The fuselage allows interior access for future repairs.
Just a few more things to consider.
Charlie Kuss