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Sherwin Williams P60G2 longevity Test

rvbuilder2002

Legacy Member
Mentor
Since it has been a while since any info about this test has been provided, I thought it was time for an update.

As has been mentioned in the past, this test is about as un-controled as any can get and it in no way am I meaning to imply that it compares to any of the Mil Spec lab executed tests that are commonly done to test the performance of protective coatings, but I feel it still provides some worthwhile real world situations data that can be used when making the prime / don't prime / what primer should I use, decision.

Though Sherwin Williams doesn't officially endorse P60G2 as a protective coating unless it is top coated, I think the results of this unscientific test show that it does provide a good level of protection which makes it a good choice when factored against cost, added weight, and ease of application, which is why we have used it for decades in our shop at Van's, on the production QB kits, and recommended it in our construction manual as one potentially good option.

The test -
On April 15, 2002, I made a test panel of .020 thick 2024-T3 aluminum. The panel was divided vertically into thirds with the right side third having nothing done to it.

The center third was cleaned with a wax/grease remover and the left side third was scuffed with grey Scotchbrite and then cleaned with wax/grease remover.

The left and center third was then sprayed with P60G2 mixed 2:1 - reducer : primer.

The test panel was then hung outside, but underneath an outdoor stairway so that it is not exposed to direct sunlight, etc.
For reference, we are in a rather humid/wet environment (for part of the year anyway) and the pacific ocean is about 60 mile direct west of here.

The test panel was left for about 4 years and then a 1/2" wide strip was exposed along the top by removing the primer. The surface was like brand new under where the primer was, but the right side third that was not primed had shown a very slight indication of surface corrosion.

Fast fwd 4 more years to Sept 2010. Exposed another 1/2 wide area and found same results.

Fast fwd 4 more years to Sept 2016. Exposed another 1/2 wide area ( skipped a row for better definition) and found same results.

Fast fwd to the current date and exposed another row in Oct 2020. Found same result. It may look a little splotchy in the photo but that is only because I didn't work to get every single bit of the primer off (as it has aged, removal of the primer with solvent seems to be getting more and more difficult)

As each row has been exposed, from that point on it has begun to develop some detectable level of surface corrosion and the nearly 19 years that the unprimed right side third has been exposed it definitely shows signs of corrosion but still not to a degree that would make an aircraft un-airworthy if found on interior skins.

All in all I think this shows that for a low cost, low weight gain, and easy to apply primer, it does offer some valuable corrosion protect and it will continue to be the go to choice here at Van's.
 

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Thank you

Thank you for keeping this test going.
I am reassured since I just scothbrited, acetone wiped, and sprayed.
 
On my QB, I acetone-wiped the interior of the fuselage before spraying top coat. I wonder if the acetone wipe removed a lot of the primer?

The unprotected panel looks pretty bad to me. I'm glad I primed everything that wasn't already primed by the QB folks.
 
The unprotected panel looks pretty bad to me.

Keep in mind that this test panel is directly exposed outdoors 24/7/365.

Even an airplane stored full time out side doesn't get anywhere the same level of exposure to the weather, and chemical elements that are in the air onto the untreated interior skins. In the context of RV's, since most are stored inside a hangar, it is on still another level of difference.

So I think this is much worse than you would see on any unprimed RV that was 20 years old, unless it was stored outside on an airport within site of an ocean coastline.
 
Scott: what are your thoughts on value of scuffing versus direct application?

Scuffing is clearly superior but the self etching action works very well as long as the surface is cleaned well.

Considering that it doesn't take very long to give parts a quick going over with grey Scotchbrite I think it is worthwhile, but I think some people spend an excessive amount of time on it.
 
Scuffing is clearly superior but the self etching action works very well as long as the surface is cleaned well.

Considering that it doesn't take very long to give parts a quick going over with grey Scotchbrite I think it is worthwhile, but I think some people spend an excessive amount of time on it.

Guilty as charged, sir!! (Guilty of spending excessive time on pretty much everything for that matter)
 
What are the opinions on maroon scotch Brite vs the finer gray stuff? Is the red too coarse?
 
what a good test! very well done. it shows that with a clean surface and not too much expense you can achieve good benefits.
 
What are the opinions on maroon scotch Brite vs the finer gray stuff? Is the red too coarse?

Because the maroon is courser than the grey, it takes a lot more effort to scuff a major percentage of the surface.
Think in terms of sanding with 80 grit vs 150 grit... the 80 grit will make some deep scratches quickly but will leave a lot of unscratched area between the grit particles so will require a lot more passes over a specific amount of square inches to get the same result as the 150 grit.

Course scratches aren't required.... just de-glossing. The grey does a great job of that.
 
I literally had a woman at an automotive paint store refuse to sell me primer because I wasn't top-coating it.

You need to talk with the store manager. If she is the manager, you should contact the regional manager. What you do with their paint after purchase is none of their business.
 
Ordered QB 14A

Scuffing is clearly superior but the self etching action works very well as long as the surface is cleaned well.

Considering that it doesn't take very long to give parts a quick going over with grey Scotchbrite I think it is worthwhile, but I think some people spend an excessive amount of time on it.

Hi Scott,
Ordered my QB and was so the fuse interior will be primed with P60G2.
Can I scuff and apply interior paint to the cockpit area or do you recommend priming it first with something before the paint coat?

Trying to save weight.

Thanks
 
Hi Scott,
Ordered my QB and was so the fuse interior will be primed with P60G2.
Can I scuff and apply interior paint to the cockpit area or do you recommend priming it first with something before the paint coat?

Trying to save weight.

Thanks

Paint formulations aren't what they were 25 years ago.... Now adays, a proper primer coat that matches the paint being used is important for good adhesion / durability.

I recommend a light coat of the primer recommended for the paint you will use. It doesn't even need to fully cover so you can use some extra reducer and mist it on very light which wont add much additional weight.
 
I wanted to use Sherman Williams paint on my project but the distributor here in Abbotsford B.C. is not very friendly. They would not sell to me. I ended up using Sikens primer and Emeron top coat.
 
Proper catalyst / reducer for P60G2

Can someone tell me the proper catalyst / reducer to mix with the P60G2?

I'm about to start my RV-10 emp build and this thread has been a huge help deciding whether and what primer to use on the inside. I was able to find a semi-local Sherwin-Williams place that has P60G2 in stock, but there was some confusion on what catalyst / reducer to use. The rep I talked to mentioned that the catalyst was separate from the reducer. I was under the impression that I only needed one additional part to mix with the P60G2.

Thanks!
 
Can someone tell me the proper catalyst / reducer to mix with the P60G2?

I'm about to start my RV-10 emp build and this thread has been a huge help deciding whether and what primer to use on the inside. I was able to find a semi-local Sherwin-Williams place that has P60G2 in stock, but there was some confusion on what catalyst / reducer to use. The rep I talked to mentioned that the catalyst was separate from the reducer. I was under the impression that I only needed one additional part to mix with the P60G2.

Thanks!

R7 K 44 is the Reducer Catalyst. Most of us mix 1 part primer to 2 parts catalyst. The trick is spraying it very thin. I usually make one quick pass then a second at 90°. Stop as soon as any color can be seen. That's plenty. It turns a beautiful translucent greenish gold color in just a few minutes. You can see markings and the aluminum grain through it.
Clear or clean the gun soon. It sets up quick.
 
R7 K 44 is the Reducer Catalyst. Most of us mix 1 part primer to 2 parts catalyst. The trick is spraying it very thin. I usually make one quick pass then a second at 90°. Stop as soon as any color can be seen. That's plenty. It turns a beautiful translucent greenish gold color in just a few minutes. You can see markings and the aluminum grain through it.
Clear or clean the gun soon. It sets up quick.

Excellent! Thanks for the advice! It sounds like the trick is going to be mixing up just enough to do one batch of parts and not waste it.
 
Primer choice

Great topic, and thank you for doing this long term "un-scientific" experiment.

How does the community feel about the choice in primers today? is there a significant difference between Sherman Williams, Kirker Enduro Prome, P60G2, etc?

Is there a difference between using the primer for interior parts such as ribs and using it in the interior of the fuselage? Is it OK to leave the interior of the fuselage primed but not painted?

Thank you all in advance. Relatively new to the community and am anxious to get started on the emp kit which just arrived today :)
 
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P60G2

Great topic, and thank you for doing this long term "un-scientific" experiment.

How does the community feel about the choice in primers today? is there a significant difference between Sherman Williams, Kirker Enduro Prome, P60G2, etc?

Is there a difference between using the primer for interior parts such as ribs and using it in the interior of the fuselage? Is it OK to leave the interior of the fuselage primed but not painted?

Thank you all in advance. Relatively new to the community and am anxious to get started on the emp kit which just arrived today :)

I use both P60G2 and Kirker EnduroPrime. They are totally different and used as such.
P60G2 is a wash primer. It's not intended as long term protection but obviously does an amazing job. It's also very light. EnduroPrime is a 2K (2 part) Epoxy. It's heavier but really durable. Many will also recommend Akzo or EcoPrime. Akzo is also an epoxy. EcoPrime is a water based epoxy. All good. You may want to search VAF and read specific threads.

Whatever primer, it will probably be left forever with no top coat. Except for areas where interior color is desired. That's what most do.
Whatever paint, make sure the interior color is compatible by research and testing on samples. Don't find out the hard way. I've seen airplanes with no final color. They sprayed a primer and left it as final color. Saves a bit of weight.
I have not seen anyone shoot final interior color with no primer. Typically a primer is recommended to aid adhesion. Never tried it. I do like the look of a good primer used as a final color with no top coat. Looks kinda Military.
 
Since it has been a while since any info about this test has been provided, I thought it was time for an update.

As has been mentioned in the past, this test is about as un-controled as any can get and it in no way am I meaning to imply that it compares to any of the Mil Spec lab executed tests that are commonly done to test the performance of protective coatings, but I feel it still provides some worthwhile real world situations data that can be used when making the prime / don't prime / what primer should I use, decision.

Though Sherwin Williams doesn't officially endorse P60G2 as a protective coating unless it is top coated, I think the results of this unscientific test show that it does provide a good level of protection which makes it a good choice when factored against cost, added weight, and ease of application, which is why we have used it for decades in our shop at Van's, on the production QB kits, and recommended it in our construction manual as one potentially good option.

The test -
On April 15, 2002, I made a test panel of .020 thick 2024-T3 aluminum. The panel was divided vertically into thirds with the right side third having nothing done to it.

The center third was cleaned with a wax/grease remover and the left side third was scuffed with grey Scotchbrite and then cleaned with wax/grease remover.

The left and center third was then sprayed with P60G2 mixed 2:1 - reducer : primer.

The test panel was then hung outside, but underneath an outdoor stairway so that it is not exposed to direct sunlight, etc.
For reference, we are in a rather humid/wet environment (for part of the year anyway) and the pacific ocean is about 60 mile direct west of here.

The test panel was left for about 4 years and then a 1/2" wide strip was exposed along the top by removing the primer. The surface was like brand new under where the primer was, but the right side third that was not primed had shown a very slight indication of surface corrosion.

Fast fwd 4 more years to Sept 2010. Exposed another 1/2 wide area and found same results.

Fast fwd 4 more years to Sept 2016. Exposed another 1/2 wide area ( skipped a row for better definition) and found same results.

Fast fwd to the current date and exposed another row in Oct 2020. Found same result. It may look a little splotchy in the photo but that is only because I didn't work to get every single bit of the primer off (as it has aged, removal of the primer with solvent seems to be getting more and more difficult)

As each row has been exposed, from that point on it has begun to develop some detectable level of surface corrosion and the nearly 19 years that the unprimed right side third has been exposed it definitely shows signs of corrosion but still not to a degree that would make an aircraft un-airworthy if found on interior skins.

All in all I think this shows that for a low cost, low weight gain, and easy to apply primer, it does offer some valuable corrosion protect and it will continue to be the go to choice here at Van's.

Thank you Scott for this report.

I was curious how do you determine the added weight and if you have any thoughts or experience of the added weight of other primers, i.e. Akzo vs. the primer used by VANS.
 
I use both P60G2 and Kirker EnduroPrime. They are totally different and used as such.
P60G2 is a wash primer. It's not intended as long term protection but obviously does an amazing job. It's also very light. EnduroPrime is a 2K (2 part) Epoxy. It's heavier but really durable. Many will also recommend Akzo or EcoPrime. Akzo is also an epoxy. EcoPrime is a water based epoxy. All good. You may want to search VAF and read specific threads.

Whatever primer, it will probably be left forever with no top coat. Except for areas where interior color is desired. That's what most do.
Whatever paint, make sure the interior color is compatible by research and testing on samples. Don't find out the hard way. I've seen airplanes with no final color. They sprayed a primer and left it as final color. Saves a bit of weight.
I have not seen anyone shoot final interior color with no primer. Typically a primer is recommended to aid adhesion. Never tried it. I do like the look of a good primer used as a final color with no top coat. Looks kinda Military.

Ah interesting, this is something that even while reading through the endless mess of topics about primer i haven't considered before.

Sounds like there may be some value in using a lighter "Wash" primer for areas that won't be painted or really won't ever see the light of day (inside of wing skins, ailerons, ribs, vert and horizontal stab, etc) and then going with a 2 part primer for the inside of the cabin, and just leaving it as is, or matching it up with an appropriate paint.
 
Weight

Thank you Scott for this report.

I was curious how do you determine the added weight and if you have any thoughts or experience of the added weight of other primers, i.e. Akzo vs. the primer used by VANS.

Not speaking for Scott. Maybe he has more accurate measurements.
I calculated it for P60G2. Weight was so low, it was barely measurable but was confirmed with several parts. Then the weight was calculated using total square footage of the interior including all the sub structure. Less than 4 oz. 1/4lb. I spray very thin!:D
I have an Epoxy/Paint Excel calculator on my blog with square footage of components if you want to play.
 
Not speaking for Scott. Maybe he has more accurate measurements.
I calculated it for P60G2. Weight was so low, it was barely measurable but was confirmed with several parts. Then the weight was calculated using total square footage of the interior including all the sub structure. Less than 4 oz. 1/4lb. I spray very thin!:D
I have an Epoxy/Paint Excel calculator on my blog with square footage of components if you want to play.

Thank you Larry, I agree it is not that easy to measure the weight. I always thought perhaps to mix a few 8oz cup weight it and then let it dry completely. Subtract some for not getting on the parts (overspray), perhaps 10-15% and that would be the weight per gallon of use.
 
What about non alclad parts?

I am gong to use P60G2 on my quick build RV8 as much of the inside surface of the QB assemblies are already treated with it.

My question is what about the non alclad aluminum parts? Is P60G2 still a good primer for those parts or is something different recommended? What about steel bits? I know...search the primer wars...
 
Scuffing is clearly superior but the self etching action works very well as long as the surface is cleaned well.

Considering that it doesn't take very long to give parts a quick going over with grey Scotchbrite I think it is worthwhile, but I think some people spend an excessive amount of time on it.

Hi Scott. I started using the grey scotchbrite pads with pre note however they say not to use grey as they are not aluminium oxide based as the maroon ones are...comments? cheers
 
P60G2 weight

This thread seems the best place to post this.
We always wonder how much weight we are spraying with all the various products. I weighed several parts before and after early in the build and could never make sense of the data. Basically zero weight
The numbers were so small they fall into the error range of the scale (1/10g).
Today I sprayed P60G2 on the inside of the Wing Root Fairings. I weighed them before, calculated square feet, sprayed my usual coat, cured and weighed again.
One gained a tenth of a gram. The other lost a tenth. This stuff weighs nothing and today's sample confirms all my previous weight samples.
Bottom line is that's really light protection. Maybe not as super duper as Akzo, but I bet it saves a lot of weight on an entire airplane. Better than nothing.
 
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