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Washing parts before priming - practical approach?

L

localizer

Active Member
Hello everyone,
As I'm about to start on empennage I have a myriad of questions. Here is one of them - how do you guys wash parts and dispose of the dirty liquids? The thing is that our house, and garage, where I will be building is about 100 feet away from a lake. I don't even wash cars on our driveway because I don't want any runoff to the lake...
Any suggestions how to wash with water and then with MEK or laquer thinner?

Thanks,
Yuri
 
You can let solvents evaporate. Then it goes into your neighbors airshed instead of your watershed. That's what most of the world does.
 
Washing parts before priming

First you should check the primer manufacturer's instruction sheets for the recommended products and sequence. I tried using MEK and all I got was a headache and not very clean parts.

The paint I am using recommends using Alumiprep 33 to clean and etch, followed by a water rinse, followed by Alodine 1201, followed by a water rinse, then paint when the water has been blown off or has evaporated (I usually leave it overnight).

I use two types of tanks for the Alumiprep and Alodine. For small parts I have a plastic (underbed storage) container about 2'x4'x6". When done I pour the Alumiprep and Alodine back in their bottles for the next session. For larger parts I use the box the wing parts came in lined with vapour barrier polyethylene with a drain in one corner. After use, as with the plastic containers, I drain the chemicals back into their bottles

You're probably referring to the water rinses and does this contaminate the ground water/creek/lake. I live next to a ditch that empties into a fish bearing river. I haven't tested the water in the ditch to see if any chemicals are present in it, but I suspect not. I believe the chemicals evaporate before doing so, but you'll have to let your conscience be your guide or test to make sure.
 
Going green?

Painting and paint prep is a pain in the butt, messy and time consuming. I'm doing it but I'm not sure I would recommend it to others.

If you are concerned about water run off during the wash process, I would recommend not doing it. Blow a little rattle can primer on the mating surfaces and move on. You'll probably save about 150 hours of build time as well.
 
Wash befor primer

What I do is scuff real good with Scotch brite to take the shine off and give the primer a good adhesion surface, then wash with dawn dish soap and water and a good clean water rinse, let dry in the sun.

I use Acid etch primer from Napa auto parts #7020 i do believe. Very simple it works well.

No chemicals to worries about at all.
 
Don't prime

Alclad parts. 90% of your plane is taken care of. Then you have saved money, time, weight, your health and the lake or air. Mine has not corroded out of the air yet.
 
Alumiprep 33 and Alodine rinse water waste: For very conservative users, mix the waste water with premix
concrete/ sackcrete and pour in to plastic pail moulds. Remove from moulds after 24 hours.
Store in a dry place while the casts are curring (30 days or so).
Dispose by burying. Just one guy's thoughts.
 
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PreKote is one alternative

I've just begun building and am using PreKote instead of a chromate conversion. It is easier to use and approved by the EPA. There is a how-to video on their web site (www.prekote.com) that supposedly is addressed exclusively toward GA aircraft, but by that they mean how to prep an entire bizjet. RV parts are easier by far.

I bought a large plastic "under bed" storage container and am using it as a wash basin. I spray the part with enough PreKote to thoroughly drench it, then scrub it to a lather with a stiff, plastic bristle household brush. Next, I scrub and scuff with a maroon Scotchbrite pad, spray on more PreKote and repeat the brush-to-lather step. Then I immediately rinse very completely with plain tap water.

All the rinse water can go straight down the drain. In fact, a clean laundry sink would make a good rinse basin, and I'll probably get one for that purpose. The usual last wipe down with MEK or other solvent is not only not required, it is strongly advised against. Just dry the part and prime ASAP.

As a caveat, I should state that I haven't yet had enough experience with it to give an impression of how well the primer adheres and holds up to abuse. I chose it based on the fact that the military and major airframe companies are using it. I would guess there are several on this forum who have extensive experience with PreKote. Maybe they'll chime in.

Good luck with your project...enjoy the journey.
 
Its prekote for me also, easy enough to use, not harsh on me or the environment and promotes excellent adhesion.


bird
 
I've always thought that if I were to build another I'd only acid etch then alodine the entire airplane.
 
Pro auto body supply?

Do you have a pro auto body shop near by?
I use a solvent cleaner/ degreaser called "Big Sky". Looks to be a combination
of chemicals. Works well. Just wipe the parts with
Paper towel. Primer is self etching primer by SEM.
Very nice stuff. Just hit the mating surfaces. No need
To hit the entire alclad surface.
 
don't prime

I'm with Wayne on this one. Manufacturers use ALCLAD specifically because the pure aluminum coating prevents corosion.

That being said, if the coating is scratched or damaged(ie. If your drill slips) you open up the alloy underneath the coating to corrosion.

IMHO, the only primer you need to apply is to cover up damaged spots on the coating.

Additionally, the average paint job for a single engine a/c weighs 30-40 lbs. Imagine how much extra weight priming all those interior surfaces will cost you!
Cheers!
 
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Crazy idea but you never know...

If you want to use the nasty stuff get a big pile of parts ready for priming. Go visit a local auto body shop and inquire about renting their paint/prep booth while they are closed on the weekend. A local body guy here offered to let me paint the entire plane in his shop on the weekends for 20 bucks an hour cash as long as I brought my own gun, and cleaned up after my self.
 
Soap and water

I use dawn dish soap with scotch brite, water rinse and air or heat gun dry. Final wipe with clean cloth and lacquer thinner. Alumiprep cleans real good to, the waste can be treated to neutral P.H. with baking soda and put down the drain. Alodine is nasty stuff (cromates), and difficult to dispose of properly. I believe the modern epoxy primers do not require a conversion coating to stick provided the primer is applied soon after prep. I use the axon primer (green death), and as long as its clean, it sticks.
 
For interior priming, I'd second what Wayne and others have said, "don't prime". At least don't prime except where Vans suggests priming (very few places). Vans seems to be very conservative minimalists when it comes to priming - if they say do it, I'd do it. Otherwise, unless you will hangar next to the ocean, don't do it. Save weight and time.

For finish paint, that's a long way off. If you take it to a shop, no worries. If you do it, I'd second the PreKote approach. But washing is the least of your pollution worries if you decide to paint at home. Just about everything is toxic.

Bill
 
Phosphoric acid & alodine

Creature of habit and have always used following method:
  1. Wash the plane with Dawn & rinse.
  2. Dilute phosphoric acid from "aviation paint department" at big box (diluted per instructions) and wearing HD rubber gloves go over entire area with Scotchbrite & rinse well.
  3. Brush on alodine (1201- wearing HD rubber gloves) and rinse after 20 minutes or so leaving copper finish. Let dry completely, preferably overnite.
  4. Try to shoot primer within a day or so.

This applies to fuse, wings, & other outside surfaces.

Interior I used rattlecan (Rustoleum Professional primer then top coat).
 
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The same as Wayne & Bill; shiny Alclad. A little rattle can primer where I bugger up the Alclad. After a few years I plan on CorrosionX treatment.

John
 
Cleaning wars!

You really opened the can here, my friend. This is just like primer wars! I may as well throw in my 2-cents...

A lot of people use Alumiprep to clean parts before priming, but I found an excellent product from Aircraft Spruce that I've used throughout my whole project. It's called Metalprep 79. Read about it on ACS's site. It seems to be an improved product over the old alumiprep. Anyway, it has worked very well for me and I would use it again. The cleaned parts dry quickly, come out squeeky clean, and the primer adheres aggressively to the parts. It's good stuff!

100_4552%20(Small).jpg


And if you think the empennage parts are a big batch, wait till you do your wing ribs! I have a page on my site, right here, showing how I set up a scrubbing operation outside on a picnic table and did my wing ribs:

http://www.europa.com/~swayze/RV-7A/Wings/20070803.html

As far as run-off, all the cleaning solution was contained in the scrub bucket I used. It could be carried off somewhere appropriate for disposal when you're finished.
 
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Just my $0.02 worth: From my site:

I have now begun the priming process and have finally chosen the paint, PPG Desoto EAP-12 and Desoprime 7502 (2-pack epoxy).

The main reaon for the choice is the 'relatively' more environmentally friendly (read: doesn't kill you) system, and it is a reasonable level of solution relative to the wash primer used on the rest of the quick build kit. Although I looked at chromates, the backyard nature of application, disposal issues, secondary ingestion issues (i.e. kicked up from the floor after turned to dust) and carcingenic nature of the chromates caused me to go the non-chromate 2-pack route.

The actual process I am following is:
1. Clean with a solvent (using Acetone)
2. Mild chemical etch (5:1 watered down AlumiPrep-33 in Garden spray bottle) Could use scotchbrite if looking little 'old'.
3. Application of EAP-12 (Boegel) adhesion promotor. (Garden spray bottle if required)
4. Application of 3 part expoxy primer.

I also purchased some equipment from overseas (UK). This was purchased from Andy at SprayGunsDireck.co.uk. Thier prices are excellent and service is good, even including the shipping costs which are good value.

Equipment purchased was:
1. Iwata air fed mask cheaper than here in Oz by x3.
2. Sata Minijet 4 spray gun with 1.2 SR
3. Disposable paint cup system (50 small and 50 medium)
4. Disposable gloves and paint suits (x3)

I have already noticed that although the fumes are not significantly dangerous, they are not particularly perfumed..... The face mask has come in very handy.
 
Wow! I did not think this was going to envoke so many replies! I'm so glad I asked - it is very educational for me to read all this.
I think I'm going with PreKote and with doing only mating parts. I like what is said about PreKote and also less time and weight.
Well, I'm still busy with preparing my workshop.. Not a single rivet yet:rolleyes:
Yuri
 
PreKote

I have also used it. Seems to work well and promotes good adhesion. I went with it because of the concern about chromate being used in my back yard and contaminating my ?personal? environment. We have a vegetable garden and I do not really want chromate of any type anywhere in my soil, especially if there is a good alternative.
 
Emp is a great testing ground for prep/priming

IMHO, priming is ineffective for water-tight protection and removing AlClad to prime seemed counter-productive. I chose to build per Vans suggestions about priming (i.e. only where specified). However, the tail kit is a great place to experiment with what YOU choose to do on your airplane. If you have trouble keeping scratches to a minimum and get more "warm and fuzzy" when you see matte colored surfaces instead of gleaming AlClad, then prep and prime the tail feathers (i.e. small stuff). It will be a good proving ground for your procedures and give you a feel for the time/costs involved. I have had at least one person I know who started this way and ended up going the AlClad only route. The 10 is a big airframe. Good luck with whatever way you decide to go.
 
What I did was simple, clean the metal with Sherwin-Williams Ultraclean (mainly if not all naphtha) and spray with Akzo. Very tough and protects the Alclad underneath very well. When I received a kit, I would prep everything and have a huge priming session. Since Akzo dries so quickly, it was easy.
 
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