Sherwin Williams P60 G2

Ok, please don't let this turn into a primer war.

If I decided to use Sherwin Williams P60 G2, is it best to scotchbrite the surface prior to application or would this remove the alclad?

If it removes the alclad, then you are removing the alclad, then rinsing (introducing moisture), then painting over it?

Fine (green) scotchbrite won't remove enough material to go through the alclad unless you go at it for a LONG time. I'd don't know how this primer reacts, but most of the time primer sticks like crap to alclad without some sort of mechanical or chemical etch.

s-w primer

I used the zinc chromate version of the SW primer. I think the chemistry is the same for the etching component.

I have sprayed it on clean alclad (MEK used), and scuffed alclad.

It sticks extremely well both ways.

In fact, the instructions do not indicate scuffing, just cleaning. It's a huge labor saving, not having to scuff, etch, alodine etc. Just a good clean will do. I noticed, however, that Van's scuff their parts before priming. They use the SW primer.

I'd use this stuff again in a heartbeat. I talked to the SW engineer at the factory about the application, and he also indicated that it 'locks up', providing a moisture barrier without a topcoat. I believe that this takes several weeks to cure to this state, however.

Vern Little, 9A

P60G2 does not require that you scotch bright or use a chemical etch prior to application (it is a self etching primer), but you must clean well to be sure all mill lubricates etc. are removed.
But scuffing with fine scotchbrite will promote better adheasion because you are not relying on just the chemical etch that it in the primer.

I started using Aircraft Finishing System's Aluminum Etch/Cleaner on my empenage, then used their water-based primer. I liked that process a lot, but when I ordered my QB kit, I found that Van's used the S-W primer, so I started using the S-W product (after a lot, and I mean a LOT of debate!). I have continued to use AFS's etch/cleaner to prep all of the parts, and the S-W primer seems to stick very well. The primer doesn't seem to come off when parts get banged around using this process, but obviously it comes off with scotchbright or sanding.

For what it's worth, when I first switched to the S-W product, I test-primed a couple of parts - one with AFS's etch/cleaner, and one with no prep at all (except cleaning with soap and water). To be honest, I couldn't really tell the difference, other than the finish on the part w/o the etch/cleaner seemed to have a slightly smoother finish after priming. But that might be my imagination.

I continued to use the etch/cleaner because it is probably worth cleaning/prepping a part before priming (obviously cleaning is mandatory) and it's all done in one step.

Greg

I doesn't matter how well you think the self etching primers do. It doesn't hurt the alclad to scuff it a little. It will assure the paint sticks. I've done pull tests with different stuff and have seen paint come off in both cases. The best course is to scuff it a little and then clean it with mild soapy water. When I say clean it...I mean CLEAN it. Mild soap does not mean barely any soap. It simply means a good lather of dish soap. (Before you quote me..Go read first)Do it several times until you are absolutely positive that it is clean. Cleanliness is the one thing that can hurt you the most down the road. I would not even attempt painting an exterior finish without the self etching primer or a good deoxydine/alodine treatment.

And another thing...if you have a Labrador retriever..don't let him scratch his back on all your aircraft parts..especially the bottom of the fuselage!! The oils in their coat are a pain to get off the aluminum.

http://experimentalrv7.com

I washed the skins and all other parts with warm soapy(dish soap) water and a red scotchbrite pad. Rinsed well and let dry. Right before priming I lightly wiped them with acetone and sprayed the SW P60. It worked very well for me. The only problem I had was the primer didn't spray very well until someone told me to use 2 parts activator to one part primer instead of 1-1. It leaves a light greenish gold tint when dry. You can see some of the parts I primed like flap brackets and skins on my website. There is even a picture of me scrubbing down the parts. www.jimsairplanes.com I hope this helps!

rv9aviator said:

The only problem I had was the primer didn't spray very well until someone told me to use 2 parts activator to one part primer instead of 1-1.

Click to expand...

Actually the instructions on the can say to mix 1.5:1 reducer to primer, but I have found some of the cans to be slightly thicker and spray better by adding a little more reducer.

Scott

You're right, it was 1.5 to one. 2 to one sure does spray better though.
One other thing, you need a drill motor with a paint mixer on it to get the stuff mixed properly. Mine must have sat in the store for a while cause it was like clay mud in the bottom of the can. Once I got it stirred up well it was fine.

I scuff lightly

I've been using the P60G2 on my entire project and I love it. I scuff my parts lightly with a gray scotch pad and then wipe them off with a wax and grease remover type of preclean. I've also used laquer thinner to wipe the parts clean before spraying with good results. I wouldn't recomend using soap and water for a preclean.

Don't use alumiprep or alodine before using P60. The label warns against this. When all else fails do what the label says!

I don't think the scuffing is required but it sure can't hurt to give the primer some more "TOOTH"

I undersand there are two versions of P60G2. One has a chromate in it and the other does not. Every can I've had listed chromate listed on it.

For the best results be sure and use 1 part primer to 1.5 parts reducer! Also don't mix up more primer than your spray gun can apply in one application. I found that if I mix up a big batch of primer, spray part of it, then come back and refill my gun with the remixed primer it makes a sputtery mess. A sort of skin forms within the premixed primer while it sits in the pot. This can hapen in just a few minutes. Once this gets ino your gun it will never spray right again untill you clean out thoughly.