PreKote Question

I have a question about prepping parts with PreKote for priming with SW P60G2 Industrial Wash Primer.

Previously I have been sanding (scuffing) all shiny surfaces with Scotchbrite pads to a dull finish in order to get good adhesion of primer and then washing with Lacquer thinner. Primer sticks great, but all this sanding and washing with lacquer thinner is a bit of a pain.

As I read about PreKote, it's not clear to me if I can avoid all this tedious sanding before washing with PreKote. If I simply wash with PreKote and scrub (lather it up) with scotchbrite pad as per instructions, does this properly prep the factory surface without having to sand all the parts to dull finish by hand before wiping down?

It's not clear to me from other posts if I can avoid this initial "sanding" of the parts before using PreKote. Can someone give me their insights?

Hi Randy,

I would suggest using the Prekote at 100% and lathering with a maroon scotchbrite pad. Lacquer thinner isn't necessary as prekote does clean the aluminum oxidation and any light oils. I would suggest that if you have any adhesive contamination that you use goo gone or a solvent on those areas first. This system has been working great for me. The real test was using gorilla tape over the akzo when I was rolling the leading edges. The AKZO held up like a champ. Good luck!

prep

Two types of adhesion "mechanical" (sanding) and "chemical" (solvent) if the product can "bite" into the substrate with one of those your good to go. With that said do a test of no scuffing leave it sit for manufacture full cure time and see what it takes to scrape it off.( read up on all the manufacture data they do all that testing for you to see) On aluminum I've always abraded the the surface metal prepped than prime just to be safe. I've seen a Cessna 180 K model factory sea plane mod and inside the wings the Zinc primer was coming off in dollar bill size sheets. maybe no prep? Just depends on where your priming I own a 70 year old Cessna with NO PRIMER and inside the air frame looks pretty good.

At the beginning of my build I bought a 5 gallon bucket of PreKote and will use almost all of it for the RV-10. Yes it is tedious and requires some elbow grease but well worth it.

My procedure:

1. Put on Nitrile or Latex gloves and keep them on for entire process (very important as it prevents oil from hands from contaminating parts)
2. Spray product on shiny aluminum
3. Scrub with maroon scotchbrite pad until all shiny aluminum is scuffed and nice gray lather is formed
4. Rinse well and make sure water sheets off nicely (no water beads)
5. Hang parts in paint booth to dry

The whole point of PreKote is to eliminate having to use other harmful products...no Alodine, no acetone. I am anti Alodine big time!

I highly recommend AKZO two part epoxy primer, the stuff is bulletproof. I have no experience with other primers though.

Cleanser

Good advise about mechanical, chemical adhesion and removal of Aluminum Oxide.
If you want another option, try the same scrubbing process but use Bon Ami cleanser.
It's my choice with P60G2. Low cost and works great.

I use PreKote and think it works great! I use as directed and spray it on the part, do a scotchbright scrub in one direction, spray it again and go 90 degrees from the first way... then rinse with water and let dry.

The Precoat info says it replaces acid etches and conversion coatings

P60-G2 primer is a self etching primer. It is specifically designed to not require pre-eteching or use of a conversion coating.

In my opinion, you would be going to a bunch of extra work and expense using it as a prep for P60. Particularly if you are pre-scuffing all surfaces just before priming. If you were using a nonself etching (epoxy) type primer, then it would probably be a very valuable step.

Cleaning the parts well is still important but that can be done with a good wipe down with an inexpensive prep solvent... even colman stove fuel (naptha).

Since you're scrubbing the aluminum with a scotchbrite pad while you are using the PreKote it will still end up with the same dull finish you get with your current process where you scrub it with the scotchbrite pad before washing. Of course I'm no expert, and have never used PreKote, but I don't see much of a difference in the end result between scuffing before washing vs scuffing while washing with PreKote.

Thanks CES 140 for "mechanical" VS "chemical" etching. Helps me understand it much better.

In my opinion, you would be going to a bunch of extra work and expense using it as a prep for P60. Particularly if you are pre-scuffing all surfaces just before priming. If you were using a nonself etching (epoxy) type primer, then it would probably be a very valuable step.

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rvbuilder2002, can you clarify for me... I'm trying to avoid the pre-scuffing and saving at least one step. Are you saying that the SW self etching primer can be applied with no scuffing (mechanical etch) or PreKote (chemical etch) as long as it's clean? Will SW P60 stick to aluminum oxide without pre-etching it in any way?

Since you're scrubbing the aluminum with a scotchbrite pad while you are using the PreKote it will still end up with the same dull finish you get with your current process where you scrub it with the scotchbrite pad before washing. Of course I'm no expert, and have never used PreKote, but I don't see much of a difference in the end result between scuffing before washing vs scuffing while washing with PreKote.

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Tim,
I get your point, but the first batch of parts I scrubbed with scotchbrite to get dull finish (mechanical etching), then used scotchbrite pad soaked in lacquer thinner to clean, so in affect, we using scotchbrite pad twice. I'm thinking if I can chemically etch parts to that dull gray finish, it will take a lot less "scrubbing" than using the scotchbrite pad alone.

Fundamentally, I'm just lazy and looking for the path of least resistance.

rvanstory said:

Fundamentally, I'm just lazy and looking for the path of least resistance.

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In that case, scuff with maroon ScotchBrite pad, wipe clean with a lint-free cloth dampened with Coleman Lantern fuel, then shoot the primer. Not only is it lazy but it works great.

The P60 is still stuck tight to my RV-6 after nearly 20 years using that method.

rvanstory said:

Fundamentally, I'm just lazy and looking for the path of least resistance.

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I completely understand! Since I haven't used PreKote all I can offer are my opinions based on what I read on their website, which I'm sure you've also read. They have an FAQ (on this page: http://pantheonchemical.com/prekote-surface-pretreatment/) asking "How does PreKote prevent corrosion?" and the answer is

"The application process cleans the surface and changes the surface tension which creates an extremely strong bond for coatings to stick to. This strong bond prevents corrosion."

So I can't say for sure whether the part will end up with the dull finish you are looking for, but to me this says that either way the surface should have been changed enough to provide good adhesion with your primer. Sorry if that isn't helpful!

rvanstory said:

rvbuilder2002, can you clarify for me... I'm trying to avoid the pre-scuffing and saving at least one step. Are you saying that the SW self etching primer can be applied with no scuffing (mechanical etch) or PreKote (chemical etch) as long as it's clean? Will SW P60 stick to aluminum oxide without pre-etching it in any way?

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Deglossing the surface is best practice to assure good adhesion but not necessarily required.
The self etching performance of P60-G2 is actually quite good as long as the surface is cleaned really well.

I recently posted some updated info to the Van's facebook page for the test I have had going for many years. A portion of the test piece was not scuffed but only cleaned just before spraying. After 15(?) plus years stored outside, there is still no indication of delamination.

I usually scuff skins but don't spend too much time on irregularly shaped parts (but I clean them well). Always sticks very well.

prekote

Not sure why there is confusion here. Watch the video produced by Prekote (easy to find online) and follow the directions in the video. Yeah, there is some elbow grease involved but the simplicity is there. You can use an organic solvent, lacquer thinner, mek, toluene but not necessary. A good water rinse and shoot it. Per Prekote's instructions.
This has worked just fine for me. Rule of KISS.