What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

PPG DX-503

acam37

acam37

Well Known Member
I need some advice on using this stuff. After prepping our fuselage "by the book" we applied PPG DX-503, let it sit for 4 minuets, and rinsed. Instead of getting that uniform golden color we got golden streaks along wing some blueish tint. I"m wondering if this is what it's supposed to look like after application? In my mind I was thinking the entire fuselage was going to be this evenly golden color without all those streaks. And what about those blue streaks?
921397ac2356419036a33826a4a3343e_zpsebpvabim.jpg
[/URL][/IMG]
89543bbad994af1ebb7476735f394712_zpsij1yowgg.jpg
[/URL][/IMG]
603d9932b34c5c0e8e6cf2ad2bca5fed_zps2wjavexg.jpg
[/URL][/IMG]
 
I haven't used that product specifically but it looks like the surface needed to be cleaner and the DX503 needed more time before rinsing. I'm at a loss with the blue streaks. When I get streaks they are usually brown in color. Some brands of conversion coating color more than others with some actually being clear.

If you are sure the skin was cleaned well and the DX503 was applied evenly then wipe the skin down with MEK on a lint free rag and prime. Primer should be applied within 24 hours of the conversion coating being applied for best results.
 
The surface was first treated with alumiprep, thoroughly rinsed with water, then it was cleaned with a scotch bright pad using water and "dawn" dishwashing liquid. I don't know how much cleaner I could have got it? One section was done with a brush which got the results stated in first post, so I tried applying it with a rag. Same results. So finally I used a sprayer to try and get a more even coat. All three application methods created the same results.
 
Old Product?

I am not familiar with the product you are using, but Aluminum looks like that if you use alodine conversion coating that is old. Does the product you are using look clear, or does it have "floaters" in it, or anything else to indicate chemical change?
 
Product was brand new. I picked it up from the PPG paint supplier on Friday and opened it just before use. This airframe is 24 years old. We sanded to bare metal and I used a flap brush wheel around all the rivets. No metal wire wheel or wire brush was used. Only sand paper and the red 3M scotch brite pads. After the final wash and rinse, the water sheeted off like it is supposed to do, indicating a clean surface. Also we never touched it after cleaning to assure no contaminates from our hands got on it. So all that's left is the product itself. I was under the assumption that DX-503 is the same as Alodine 1201.
 
DX503/Alodine 1201

My Alodine is very old, shows floaters and is discolored. Does the same thing your DX503 did. That is all that I know. I will be buying new before too long, as it is getting towards paint time for me.
 
I've had the same gold/clear/blue result from a fresh bottle of alodine 1201 after a phosphoric acid surface cleaner. Don't know why it happens.
 
I have seen that happen sometimes when I alodined skins before assembly.

I think it was because the alodine liquid was too thin or diluted. It needs to really wet the area and stay put without agitation. The blue parts could be rubbed/washed off with gentle scothbrite action and be re-alodined.

It never seems to happen with parts dipped into an alodine solution.
 
Wash wish soap is the first step. I use Eldorado ED-500. Anything similar is good.

Wash with the etch second. Lightly scrub with scotchbrite while the etch is on the skin. Rinse very well.

Lastly spray on your alodine starting from the bottom and go up. When you rinse, start at the bottom and go up. If a spot looks light you can hit it again. The color of the alodine treated metal will lighten in color overnight.
 
I've only seen the blue with old and assumedly contaminated Alodine (Chromic acid). I figured I got some phosophoric acid in the alodine or some other contaminant. Look in the bottom of the bottle and see if there is any sludge. Are you sure you got new/unopened?
I've never seen blue with new solution (I mix up from powder and distilled water).
The streaking is pretty much going to happen unless you can submerge the parts. Not pretty, but not an issue.
 
Thanks for the replies. I researched it and asked a few local RV builders if my results were acceptable. The consensus was that it was OK. So this evening I wiped everything down with MEK and shot the epoxy primer.
 
You must log in or register to reply here.
Back
Top