Another Primer Question. Sorry i have to ask

So I?ve been trying out different primers lately and I think I found the one that I want to use for my internal parts. I have a question. Do the internal parts need to be able to hold up to solvents? I think I want to use the SEM EZ-Coat product but the only problem is that it doesn?t hold up to solvents. I did an oil test and it wipes right off without staining but when I wiped my test part with MEK the paint comes right off. My Scratch test, Bend test and tape pull test all passed. The only thing that I worry about is when the External of the plane gets prepped for painting and if any cleaning solvents gets into the internal area and starts to eat away my coating. Should I worry about this? Correct me if I?m wrong but the only way to keep this from happening is if one uses the two part epoxy coating product or the SW P60G2 wash primer. Correct?

I initially thought I wanted to use an aerosol can primer. The more I thought about how many cans of primer I would use, and how long it would take to spray the parts, the more it looked spraying epoxy primer was the best solution. I suggest you buy some Akzo 463-12-8 and a cheap HVLP gun. The Akzo is very easy to mix (1:1) and spray. I still cannot understand the reasoning behind the SW wash primer. Wash primers are designed to by top coated with paint within hours and were never designed to be a corrosion resistant coating, much less a stand alone coating.

Mike H said:

I still cannot understand the reasoning behind the SW wash primer. Wash primers are designed to by top coated with paint within hours and were never designed to be a corrosion resistant coating, much less a stand alone coating.

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We'll, Hughes helicopter was using SW P60-G2 in the 80's as a surface protectant without top coating.
I have a test sample that has been hanging outdoors (protected from sun exposure) for almost 12 years and there is no corrosion under any of the protective coating.
It contains chromates and does a good job of protecting aluminum. I admit it doesn't meet any mill spec when used by itself and is not impervious to all fluids and chemicals, but it is a good low cost easy to use option that I still use regularly.

I was not aware that Hughes Helicopters used it on the interior of their airframes without top coating it. Still does not seen advantageous compared to solvent resistant epoxy primers since you still have to mechanically scuff and clean the surface prior to application, as well as mix and spray with an HVLP gun. Cost and application time appears to be almost identical, so why not use a two part epoxy primer that was designed specifically for use on aircraft?

Mike H said:

I was not aware that Hughes Helicopters used it on the interior of their airframes without top coating it. Still does not seen advantageous compared to solvent resistant epoxy primers since you still have to mechanically scuff and clean the surface prior to application, as well as mix and spray with an HVLP gun. Cost and application time appears to be almost identical, so why not use a two part epoxy primer that was designed specifically for use on aircraft?

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I'm not interested in joining a primer war / debate (you obviously feel you have made the optimal best choice), but I will try and answer your questions for the benefit of others that might be interested.

I don't know how the cost compares to the product you are using, but ... $130 will buy enough P60-G2 to make almost 2 sprayable gallons (enough for a couple complete RV airframes)

P60-G2 is a self etching wash primer.
It does not require scuffing for good adhesion, just thoroughly cleaned parts.

It drys super fast (when properly applied). By the time clean up of the gun is completed, you can start riveting parts.

Why not use epoxy primer?
Because to use it properly and gain the full benefits....
It usually does require scuffing and/or etching prior to application
For full Millspec level protection it generally also requires a conversion coating process (alodine) prior to application.
It generally contains a higher level of dangerous chemicals.
It generally costs more (particularly if you consider the extra materials such as alodine).

For anyone interested in reading more about making a primer choice for corrosion protection, have a look at this article written quite a few years ago by one of our local RV builders (Brent Anderson), called Priming - A beginning dilemma (beginning on page 45 of THIS document )
Many of the products have changed since then, but the thought and reasoning processes used to make a choice are still the same.

The same document also contains the first report of a test of SW P60G2 primer for corrosion protection. It was only about 3 years old at the time (2005) but the test sample is still outside, now over 14 years old, with the same results.

Major sub assy priming

So this thread got me started and wondering if priming my major subs prior to closing is the right thing. I am getting my tool box kit today to build for my nephew and get my skills back up to speed.

I am about convinced to go with Mikes AKZO 463-12-8 but I looked it up on A/S and it is 300 hundred bucks for 2 gallons of primer and some thinner. Sticker shock. Phew. I thought I read a gallon would do two RVs. And the shelf life is two years. Can I be done that fast?

I am still on the horns here.

Do I need to squirt the inside of my tail kit and wings as I get them riveted together? And is there source for this AKZO that is not 2 perishable gallons at a time. If not I may go with the rattle can wash.

The thinner/reducer IS NOT required for spraying 463-12-8. A two gallon kit is a little less than $200.00 Actually as mixed without thinner, I could go to a smaller daimeter nozzle/tip on my HVLP gun. Right now I am using a 1.5mm tip and I only have the fluid needle one turn out from the seat. The primer will not go bad in two years unless the lids are not sealed correctly.

My process is to deburr all parts, scuuf with maroon ScothcBrite, clean with Acetone then prime. The following day the paint will be hard and ready to final drill, dimple, assemble etc. Some builders also etch the parts after scuffing as an additional step prior to priming. I have also been priming both sides of my skins (except interior of tank skins).

463-12-8 and TR-19 thinner are heavily MEK based, so don't waste your money on TR-19. Just grab some MEK if you need to thin (which generally you don't).
(MSDS's can help you see "behind the curtain" and Butanone, BTW, is MEK)

Graco (see VAF ad sidebar) has AKZO cheaper than Spruce.

Wear an organic filter respirator.

TedsNumberOneSon said:

So this thread got me started and wondering if priming my major subs prior to closing is the right thing. I am getting my tool box kit today to build for my nephew and get my skills back up to speed.

I am about convinced to go with Mikes AKZO 463-12-8 but I looked it up on A/S and it is 300 hundred bucks for 2 gallons of primer and some thinner. Sticker shock. Phew. I thought I read a gallon would do two RVs. And the shelf life is two years. Can I be done that fast?

I am still on the horns here.

Do I need to squirt the inside of my tail kit and wings as I get them riveted together? And is there source for this AKZO that is not 2 perishable gallons at a time. If not I may go with the rattle can wash.

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Terrell - fairly expensive, yes, but AKZO is super primer IMO. I think once you see how easy it is to apply, the durability, and the level of protection it offers, you wouldn't be as concerned about the cost. I, like Mike, am doing both sides of the skins and feel much better about my parts lying in wait... I swear I can watch aluminum corrode in my garage - especially this time of year

Dues have now paid for themselves

60av8tor said:

Terrell - fairly expensive, yes, but AKZO is super primer IMO. I think once you see how easy it is to apply, the durability, and the level of protection it offers, you wouldn't be as concerned about the cost. I, like Mike, am doing both sides of the skins and feel much better about my parts lying in wait... I swear I can watch aluminum corrode in my garage - especially this time of year

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This is awesome and I am growing accustomed to this community and I am glad to be a member of the AirForce. I just sent the bookmark for the Graco to my email for ordering next payday. I think my Dad had a HVLP spray rig and I know for sure has a turbine. This response thread made my whole week.

Practice tool box and new air hose came today. Maybe some brdtbrdtbrdtbrdt noise next day or two.

Again thank you guys a brazlian for the excellent coaching. Esp the guidance to sidebar. I can spring for that.