What's new
Van's Air Force

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

Primer-Sherwin Williams P60G2

dhmoose

Well Known Member
Does anyone know what a good P60G2 primer coat looks like? I've used the primer on various sections and get a light green coating after spraying it with a 1:2 p60g2 to reducer ratio. This coat looks considerably thicker then what Vans does on their QB kits. Thoughts? Thanks!
 
Van's primer doesn't have the green pigment in it. For some reason it is sold overseas without the green pigment. At least that is what I was told. If your paint is splotchy try using a little more reducer. I ended up using 2 parts reducer or activator to one part primer.
 
The primer Vans uses is not a corrosion preventative primer and is called a wash primer. The sole purpose of this type of primer is to promote adhesion, and not for corrosion. I am not at home or I would provide you with the part number of the Vans paint. The 2 part primer that I used on top of Vans primer, and for all subsequent un-primed parts is shown on my website www.mykitlog.com/peytonb. Normally you do not need to use a thick coat to promote good adhesion, but because you are probably using it as a corrosion barrier, you should put it on thick. This stuff is really bad for you to breath, so a positive pressure mask is a must!
 
This is a true statement but it does have protective qualities.

The primer Vans uses is not a corrosion preventative primer and is called a wash primer. The sole purpose of this type of primer is to promote adhesion, and not for corrosion.

There is no coating that "prevents" corrosion, only gradients from no protection to very good protection. Van's "unofficial" testing of the wash primer showed it protected significantly better than unprimed Alclad.
I am told the test was strips hung from the outside staircase for a year at the factory in the elements. The unprimed Alclad showed a lot of surface corrosion. The wash primer showed none. The factory is located in an environment of lots of rain, little or no salt, and pretty low humidity (when it is not raining!, it's Oregon, it rains a lot here!). That test is what they based the decision to use the wash primer on the QB's I am told.

If you read the wash primer manufacturers own data it specifically says it has minimal corrosion protection, or "poor", I believe it stated. It is still far better than nothing even though many thousands of airplanes live and fly today without any protection, and no corrosion.
 
Dont put it on thick...

Normally you do not need to use a thick coat to promote good adhesion, but because you are probably using it as a corrosion barrier, you should put it on thick.

I believe SW specifies 4 mils. It warns that thicker coatings may cause adhesion problems (peeling) with the primer.
 
I believe it should be 1:5 to 1 ratio

Does anyone know what a good P60G2 primer coat looks like? I've used the primer on various sections and get a light green coating after spraying it with a 1:2 p60g2 to reducer ratio. This coat looks considerably thicker then what Vans does on their QB kits. Thoughts? Thanks!

It states this on the product. From David's kit log, that shows a bit more pigment than what I like to see, although I had many parts look like that and I would not do them over.
The appearance should be a transluscent green without any small dots of green or blotches, in other words a continuous smooth sheen of very light green. That is about the 4 mils recommended by SW. Anything with a mottled appearance usually means that it did not atomize very well out of your gun.
It takes some practice to get the gun set. HVLP's are a bit tricky with this product but you can still get a good result with the right set up. Take practice shots on some scrap until you get that suttle sheen and then blast away.
 
Jonjay,
In regards to the corrosion protection, one only need to read the data sheet for the wash coating Vans applies. It states, as I recall, it should not be used for corrosion protection. My only point is that Vans could have selected a much better product at very little difference in cost, and saved a lot of us a lot of time.
I really don't care how many production spam cans are out there flying without any protection. My current 25 year old hangered Piper does not have it and I can already see the start of discoloration in the wings which was not there 20 years ago. In 1980 it was a Piper option to have the interior panels treated, unfortunately the guy who owned the aircraft prior to me chose not to pay for the option.

In regards to the RV-10, when I sink almost $200K and 2 years into an airplane, I would like to think that it will have the best solution possible for corrosion protection. Most who are building the slow kits are using the two part epoxy chromates which accomplish this to a much greater extent than a wash primer.
In regards to the thickness of the coating, I understand the data sheet does indeed specify a very thin layer for use of the product as an undercoat layer, but there are a lot of areas that will never get a finish coat that will benefit from a thicker coating. By "thicker" I mean covering the underlying material sufficiently that it appears a consistent green. I personally have not seen any issues of pealing. I would guess if it was put on real thick there could be issues. Like I stated, I have not seen this peeling issue. It seems once this stuff is put on it is extremely durable.
 
Thanks!

I appreciate all the replies and comments. My intention was not to start a primer war, but to get opinions on the method to use for SW P60G2. Another way to word the question would be..."What does 4 mils of SW P60G2 look like?" In my experience (empennage), I have strayed from the manufacturer recommended 1:1.5 and used 1:2. It seems to work well but as was mentioned, this material is difficult to shoot with an HVLP gun. Avoiding runs (it has a consistency like water) and blotches takes patience but with a couple coats, the result seem good. I get a full surface coat with no "untouched" areas. I have not seen any peeling, even when I have scuffed an area accidentally when riveting. So, I'm confident that the coverage is good and will last. What I can't be sure of is the "corrosion protection" of it and the ideal thickness (SW does say that it does not provide corrosion protection in their sheet). Since Vans tested it, speaks favorably about it, and uses it on the QB, I'll assume the corrosion protection is sufficient. So, the only issue is, "What does 4 mils of SW P60G2 look like?" (without a paint thickness tester)
 
A few points about P60G2 (and protective primer in general)

Jonjay,
In regards to the corrosion protection, one only need to read the data sheet for the wash coating Vans applies. It states, as I recall, it should not be used for corrosion protection. My only point is that Vans could have selected a much better product at very little difference in cost, and saved a lot of us a lot of time.
I really don't care how many production spam cans are out there flying without any protection. My current 25 year old hangered Piper does not have it and I can already see the start of discoloration in the wings which was not there 20 years ago. In 1980 it was a Piper option to have the interior panels treated, unfortunately the guy who owned the aircraft prior to me chose not to pay for the option.

In regards to the RV-10, when I sink almost $200K and 2 years into an airplane, I would like to think that it will have the best solution possible for corrosion protection. Most who are building the slow kits are using the two part epoxy chromates which accomplish this to a much greater extent than a wash primer.
In regards to the thickness of the coating, I understand the data sheet does indeed specify a very thin layer for use of the product as an undercoat layer, but there are a lot of areas that will never get a finish coat that will benefit from a thicker coating. By "thicker" I mean covering the underlying material sufficiently that it appears a consistent green. I personally have not seen any issues of pealing. I would guess if it was put on real thick there could be issues. Like I stated, I have not seen this peeling issue. It seems once this stuff is put on it is extremely durable.

It is correct, that Sherwin Williams does not promote P60G2 as a corrosion protective coating on aluminum.
This is also true of a large # of the other coatings that RV builders choose to use. Most manufacturers require the coating to be paint top coated for true protection.
P60G2 has Chromates in it. This is a common ingredient of protective primers (like the popular Tempo brand Zinc Chromate primer). The chromates act as a sacrificial anode to the development of corrosion.

As mentioned by Jonjay...Vans has an outdoor exposure test sample that has been outside in the Oregon weather, but under cover so it has no U.V. exposure. It has been in place since April, 2002, so it has been in place almost 9 years. A recent inspection showed that the bare alclad surface under the P60G2 coat has zero indication of corrosion. The bare, uncoated portion of the test sample has corrosion.

My experience using P60G2 for the past 20 years is that there can be variation from one can to another. Often it is unsprayable if mixed to the recommended 1.5:1 ratio. I usually mix at 2:1 (but not always...depends on the consistancy of that particular can).
Most beginners tend to spray it too heavy. When properly mixed, spray just heavy enough to wet the entire surface (resist the temptation to add more regardless of how dark it looks).
The color tends to darken slightly as it dries.
Proper application results in what looks like a very light green anodized coating.
 
I have to agree with Scott. I've been using Sherwin Williams wash primer since the mid 1970s and found it to be a very good as a corrosion control. I have had conversations with Sherwin Williams over the matter and they admit that even though it wasn't formulated for that purpose, it works quite well.
 
Correction on thickness for SW Wash Primer

I apologize as I mistated the thickness. It is not 4 mils, it is .4 mils, dry.
I still stand on my good, better, best approach but will never argue about the merits of anyones own personal choice - It is a choice with pluses and minuses to each.
Good - Alclad
Better - Wash Primer
Best - Epoxy/other designed top coats.

I was not aware that SW Wash Primer had any chromates in it. Learn something new everyday.

If anyone is curious, although not directly RV related, I would be happy to post pictures of various types and levels of corrosion I have found in my restoration work. It is quite eye opening when you actually see the start, middle, and finish of the process. My current project has everything from simple surface corrosion (piting), filiform in the Zinc Oxide coatings, filiform in the base metal, and exfoliation.

If you are doing any kind of regular inspections you should be able to identify the start of a corrosive event and take immediate action to mitigate it before it becomes a structural issue.
 
My project is a very slow build, sorry Mel, and the P60 primer I applied 7 years ago looks exactly the same now as it did in 2004. This would be the same as any airplane stored in a dry hanger.
 
Last edited:
SW info

I've used the P60G2 for a few years now and I'm happy with the protection, ease of use, etc. That said, I take respiratory precautions and treat the stuff like "green death" (nickname shared by the SW rep).

SW asks for a 1.5:1 ratio of reducer to primer. I believe Wally at SynergyAir liked a 3:1 ratio instead.

Here the data sheet from SW:

http://www.paintdocs.com/webmsds/webPDF.jsp?SITEID=STORECAT&lang=E&doctype=PDS&prodno=P60G2

Does this answer your question or were you looking for something else?

David
 
The 1.5 to 1 will look splotchy for sure. I used 2 part activator to 1 part paint with good results. Just don't lay it on until you get a dark green color. A light gray green is all you need. A lot of my parts were primed in 2004 and they still look like new with not a hint of corrosion. It would depend on where you live I guess but I'm not close to an ocean and salt water. Another thing, ask for OEM pricing at the Sherwin Williams store. If they will go along with you it will be much cheaper.
 
Last edited:
Spray a light coat on bare aluminum. Compare it to a non-primed piece. If you can see any difference at all, you have enough. VERY little is needed.
 
Pretreatment for Sherwin Williams R7K44

I found this thread reading about primers and decided to use the Sherwin Williams primer.
Question
How are you prepping the surface?
I assume scotch brute maroon pad followed by a wipe with Acetone or similar product.
 
I found this thread reading about primers and decided to use the Sherwin Williams primer.
Question
How are you prepping the surface?
I assume scotch brute maroon pad followed by a wipe with Acetone or similar product.

You are good to go for interior pieces and things that do not get a top coat. However, for maximum durability, scotch bright maroon is no where near as agressive as I see the pro painters going. I think it is fine for interior surfaces, but for exterior probably not agressive enough. Perhaps some of them can chime in on their prep.
 
Interior priming

Thanks
I'm priming interior surfaces with it.
I called Sherwin Williams. They recommended some sort of water borne cleaner.
I'm still searching for the name.
 
Temperatures

I used the SW primer on my build for all the big parts and only used the rattle can primer for small parts or when I did not want to mix up the SW primer.

I found mixing it 2:1 best but I also found that warmer temperatures prevented the splotchy speckles. At lower temperatures <65F, I would get splotches. When the temperature was above this I would get and even light green coat. I like this stuff even though it was a pain to mix because it has a tough finish. You can scratch your nails on it and it will not chip up the primer, not so with the rattle can stuff.

I had no experience spraying primers or paints before my build so factor this in with how you weigh what I wrote, I can only tell you I got better with time and personally I think the primer is very tough finish and will do well as a light weight corrosion protector.

Cheers
 
thanks

Thanks. That's exactly what I wanted and have been hearing from others. Light is good. Especially in the tail.
 
I've been using Sherwin Williams wash primer since the early '70s (long before Van's offered a Q/B kit) on everything from tractors, to cars, to airplanes. Back then it had a different part number, but was the same product as P60G2.

S/W engineering and I had a talk and even thought they insisted it is not designed for corrosion protection, they could not recommend a better suited product.

My 23 year old -6 still looks the same inside as it did when originally coated.
It should be put on very thin. If you can tell there's anything there, that's enough.

Bad: It's expensive and nasty to the lungs.
Good: It's very light weight and works very well.
 
Last edited:
Total newbie here. Expecting RV-14A empennage kit in a few days. Doing reading, research, etc., to get ready!

So what would be the sequence here. Let's say I'm starting the vertical stab. Would it go something like this?

1. Deburr all parts for a given assembly step
2. Wash/prep then prime using P60G2
3. Assemble then rivet the assembly

Or would you build an assembly first then prime?

Also, is the SW for internal parts only, ie those parts that will not eventually be painted?

Thanks,
Chris
 
Hey Chris,
Plenty of info in the primer wars discussions.
If you want to swing up to Venice, I can show you what I do.
Or, there are plenty of other builders in your area.
I'm a Akzo primer guy, so YMMV.
Just before you are ready to do final assembly/riveting:
  1. Clean/degrease - Naptha, Prep Sol, whatever you like
  2. Phosphoric acid etch and Scotchbrite scrub
  3. Chromate convert (Alodine)
  4. Prime
  5. Assemble/rivet

If you are using an etching primer, the etch and conversion steps are skipped, but I still recommend a good scotchbright scrub.

Prime everything unless you plan to polish. That's my advice for coastal FL.
Good luck!
 
P60G2

Chris
Always treat or prime before assembly to protect areas that touch. Especially dissimilar metals.
Almost everyone will agree with Alodine. I chose not to use it due to it's health and environmental issues. That said, it's such a good coorosion inhibitor, I may use it on the exterior.
Any surface you expect to paint should have a compatible primer so ask the manufacturer. I did some research and asked and got a variety of answers but Sherwin Williams sources agreed P60G2 was ok under Jet Flex if sprayed within an hour for a good chemical bond. I haven't considered exterior paints yet so no treatment has been done on exterior surfaces.
One important factor to research is surface prep. You'll read almost as many opinions as primer wars.
My opinion...
The enemy if adhesion is Aluminum Oxide. It's a thin layer that forms on aluminum. Basically the aluminum version of rust on steel. Paint doesn't stick to it very well. Maroon Scotchbrite will remove it and provide some "tooth" for a mechanical bond, but will reform within hours so timing is important. I prefer to scotchbrite the flat surface before dimpling for "tooth" but clean prior to priming.
Cleaning is important. The aluminum oxide layer needs to be scrubbed off or etched off before painting and dirt and oils removed. I don't like acids and solvents much so I use Bon Ami cleanser and gray scotchbrite. Scrub well, rinse well, dry thoroughly, wipe with a tack cloth then spray.
You want a hydrophillic surface. Water should coat the metal. If it beads, it still has aluminum oxide and oils.
P60G2 goes in very thin. Mix 1 part primer:2 parts catalyst. Shoot till color change is barely visible. Touch dry in minutes. Fully cured in hours.
 
There are a lot of very good replies on this post and good arguments on all sides. I do have a question I want to throw out there for everybody. I live in southern Florida and corrosion is a big problem here. I know a lot of other RV builders are using very exotic and expensive primers. Is there any long-term evidence that these product actually perform better than an inexpensive shaker can zinc chromate primer? I don't mind spending $200 a gallon for a product that will protect my airplane but a primers only purpose is to prevent oxygen from reacting with a metal. Seems to me that any primer made for aluminum that has decent adhesion and sealing properties would have identical performance.
 
The old "shaker-can zinc chromate" primer was fine in it's day. It had little or no competition.

The biggest problems with zinc chromate are that the coating needs to be fairly thick, which means WEIGHT, and it has poor adhesion properties.

More modern etching primers are much better in many ways.
 
Thanks a lot Mel. I am planning on going quick build and the lady at Vans mentioned they only use the P60G2 and there is no option to upgrade to a different primer, so I am stuck using this product for the wings and fuselage. Wondering if I should use something different for the empennage or just stick with the P60G2 for the whole plane.
 
I have been applying primer with a sponge brush and it seems quick, easy and inexpensive. I mix it thin so if flows out well and doesn't leave brush marks. Dupont Variprime seems to work well for me. It is a metal etch primer, and has zinc chromate in it. I still scotch bright and clean with a good detergent. But even if the parts are not super clean, and have a oily fingerprint or two on them, the metal etch primer cuts right through and gives me good adhesion. I like the idea of having a good primed surface where parts are touching.

2n8psoz.jpg
 
I am able to use the same sponge brush and the same small plastic mixing cup repeatedly. I open the Dupont Variprime can and stir with large wooden popsickle stick, then transfer the primer by dipping the stir stick and scrapping on the sides of the mixing cup until I get the amount I think I will need. It is often a very small amount for small parts. When I transfer by stir stick, and not pouring, I avoid contaminating the rim of the can with primer so the lid will go back on cleanly. Then I poor activating agent in, generally about twice the amount of primer by volume, and stir with same transfer stir stick. You can sort of tell if the mixing ratio is correct by the way it flows off the sponge brush and not leave any brush marks. If has been sitting awhile and dried/thickened a bit, I will often splash a little more activator in the mixing cup to thin it out again. I am a cheap skate by nature and the waste product. After I finish priming my parts, I splash some lacquer thinner in the mixing cup, swish around with my sponge brush to clean both the brush and cup. I will sometimes use a heat gun to speed drying so I can flip my parts more quickly. I can prime parts and be ready to rivet in about 15 minutes. Yes, I am not following the mixing instructions on the can, but I don't think this stuff catalyzes in the same way that epoxy paint does, and mixing thin doesn't seem to degrade durability.
 
Sam, your method seems like a good compromise between rattle can and HVLP spray of a two-part epoxy primer. I'm intrigued. How long have you been using this method? I'm really asking how old are the oldest parts on which you've used this technique and do they still look the same as the ones you've done most recently?
 
Priming rivets

Quick question guys. Since most of the internal priming work needs to be done prior to assembly, once the parts are finally riveted together, the rivets themselves miss out on getting any primer. My question is, do I need to go back after assembly and re-spray over all the bare rivets? Not sure now corrosion proof rivets are.

Thanks,
Casey
 
Rivets

Quick question guys. Since most of the internal priming work needs to be done prior to assembly, once the parts are finally riveted together, the rivets themselves miss out on getting any primer. My question is, do I need to go back after assembly and re-spray over all the bare rivets? Not sure now corrosion proof rivets are.

Thanks,
Casey

Rivets are treated. No spray needed.
 
Just wanted to share something I read in the plans on primers. Looks like Vans actually has a short list of some specific primers that they recommend are superior (Sherwin P60G2 is one of these).

Brand / Product
DITZLER - DP-40/50 EPOXY PRIMER
DUPONT- VERI-PRIME (PRIMER #615 and CONVERTER #616S)
MARHYDE - Self-etching primer, available in a spray can as well as quarts
PRATT & LAMBERT - Vinyl Zinc Chromate, EX-ER-7 and T-ER-4 Reducer
TEMPO - Chromate in a spray can
SHERWIN WILLIAMS - WASH PRIMER #P60G2 and Catalyst Reducer #R7K44
 
where are you guys/gals buying your wash primer
Sherwin-Williams P60G2 Semi-Transparent Green Industrial Wash Primer ??

Skygeek has been back ordered, local sherwin guys ( auto) says not available thru him, only tried them due to aluminum bodies today in automotive
 
P60G2

where are you guys/gals buying your wash primer
Sherwin-Williams P60G2 Semi-Transparent Green Industrial Wash Primer ??

Skygeek has been back ordered, local sherwin guys ( auto) says not available thru him, only tried them due to aluminum bodies today in automotive

Check the SW Web page for distributors. Only the SW auto paint shops carry it. I found one in Denver. There's probably one near you too.
Try these.

FORT MYERS-METRO COMMERCIAL #2366
12990 METRO PKWY STE A
FT MYERS, FL, 33966-1403
(239) 225-0820


FT MYERS-ALICO COMMERCIAL #2445
17131 ALICO CENTER RD STE 1
FT MYERS, FL, 33912-6019
(239) 415-4025
 
Last edited:
Thank you Sir, I called the Metro store they said that part number was no longer available?
I also spoke with SW Aerospace in Tampa, he told me that Product was not designed for corrosion protection, only for prep for an actual corrosion primer...

Oh my Primer is tough
 
P60G2

Thank you Sir, I called the Metro store they said that part number was no longer available?
I also spoke with SW Aerospace in Tampa, he told me that Product was not designed for corrosion protection, only for prep for an actual corrosion primer...

Oh my Primer is tough

Well Van's has been using it for 15+ years. Can't believe any store would loose a sale that way.
If you want to use it, just buy a gallon and two gallons of catalyst. Store doesn't need a reason. They never asked me. For what it's worth, the stuff is super easy to spray, very light and won't come off (provided surface is properly prepped).
 
Last edited:
Not wanting to extend the primer wars but I am currently priming all internal parts with SW P60G2. When it comes to fuselage skins is anyone priming the outside of the skin where there are lap joints? This area would not be able to get primed and painted with the rest of the airframe.
 
I've seen it done like that before. Builders have masked off exterior surfaced of skin that get covered by a lap joint (ie. L/R wing skin joint, fwd and rear aileron skins at the spar, upper and lower flap skin)

I didn't do it, probably wont.
 
SW

"...he told me that Product was not designed for corrosion protection, only for prep for an actual corrosion primer..."

I actually spoke with a SW tech, at length, about this before I decided to prime.

It is true that the P60G2 is designed to have a top coat of something else...and that top coat is also supposed to be applied within a certain time after P60G2 application, according to the SW tech.

That said, I believe the mothership actually has a test piece that was sprayed with P60G2 many years ago, and is holding up fine...
 
Priming

Not wanting to extend the primer wars but I am currently priming all internal parts with SW P60G2. When it comes to fuselage skins is anyone priming the outside of the skin where there are lap joints? This area would not be able to get primed and painted with the rest of the airframe.

Yes. I did. Anywhere a surface would not be accessible. P60G2
 
....I also spoke with SW Aerospace in Tampa, he told me that Product was not designed for corrosion protection, only for prep for an actual corrosion primer....

Turns out that many primers are like that. Their main corrosion protective feature, as far as I can determine, is as a barrier.

Dave
 
Talked to SW Aerospace for advice

I asked my SW Aerospace rep about the recommended P60G2 primer and was told it will do nothing for corrosion resistance. They recommended and acid wash coat then a primer. They were really adamant about putting on too thick. They recommend only applying enough to create a solid film, no more than that. Below are not noted from the conversation:

DO NOT HI BUILD, only enough to create solid fill for both products
HVLP Gun is good to use
Use plastic containers to mix
Temperature at application time, ambient and surface is important
1. Scuff with Red Scotch Brite or 320-400 sandpaper
2. Clean / prep with MEK soaked Red Scotch Brite
3. Final clean with MEK wetted rag
4. Acid Wash with 484646 Wash Primer
a. Only enough build to create solid film (not big build)
5. Wait 1 hour
6. Prime with 486707 primer
a. Again, only to solid film, not thick (too thick can crack)

All prep and cleaning of surfaces and equipment done with MEK or SW 110308 (use MEK)
See PDS for proper reducer
I assume no scuff coat between acid wash and primer
Both can be brushed or rolled in a pinch, just have to be careful not to get too thick
 
Back
Top