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Help with primer issue!

97swede

Member
Hello, first post, and I need some help! I’m having an issue getting self etching primer to stick to aluminum angle. I have done all the research on priming and decided that I would prime parts with rattle can primer for the most part. After a lot of research it seemed that most folks had good success with the SES self etching primer that Aircraft Spruce sells. After a couple of attempts I am still having issues. I have tried roughing the surface with a maroon scotch brite pad, no luck, so I then went to 80 grit paper and still couldn’t get adhesion. I think I have talked enough so please see attached photos and I would love to hear how you folks that have used this have had success. Thanks!
 

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Make sure you: 1) clean the metal to get rid of oils and 2) spray a thin tack coat first, as opposed to just spraying one thick coat.
 
Prep

Hello, first post, and I need some help! I’m having an issue getting self etching primer to stick to aluminum angle. I have done all the research on priming and decided that I would prime parts with rattle can primer for the most part. After a lot of research it seemed that most folks had good success with the SES self etching primer that Aircraft Spruce sells. After a couple of attempts I am still having issues. I have tried roughing the surface with a maroon scotch brite pad, no luck, so I then went to 80 grit paper and still couldn’t get adhesion. I think I have talked enough so please see attached photos and I would love to hear how you folks that have used this have had success. Thanks!

SEM is pretty good rattle can. Shake it well.
My guess would be aluminum oxide or other contaminate. It forms fairly quickly on bare aluminum. Try scuffing while washing with a powdered cleanser. Bon Ami is best. No bleach. Comet or Ajax work but make sure to rinse well to clear the bleach. Dry and prime as soon as possible.
80 is a bit aggressive. Maroon scotchbrite is fine.
 
I used “Goof Off” to clean the part, I’m starting to think that may be part of the issue. Any recommendations on what to use for cleaning? Denatured Alcohol?
 
I used “Goof Off” to clean the part, I’m starting to think that may be part of the issue. Any recommendations on what to use for cleaning? Denatured Alcohol?

I just use acetone. Cheap and easy. I wouldn't be surprised if the Goof Off leaves residue behind.
 
Aluminum oxide

I used “Goof Off” to clean the part, I’m starting to think that may be part of the issue. Any recommendations on what to use for cleaning? Denatured Alcohol?

Ok. Back on my soapbox.
The enemy of adhesion is aluminum oxide. Similar to the red layer of rust that forms on steel. It's only a few microns thick.
It has to be removed and solvents won't remove it. Yes, you can clean with a solvent and call it good. It's your airplane. See me post above. Easy to remove while washing and no harmful chems.
 
I use lacquer thinner, then the maroon Scotchbrite, then either lacquer thinner or isopropyl alcohol, at least 91%. Clean it enough so that there's no trace of anything left on your rag or paper towel. You'll need to make several passes with different pieces.

I get excellent results with SEM.

Dave
 
Just me

I tried rattle can primer but was never happy with the adhesion. I bit the bullet and went with Sherwin Williams P60G2. I thought it would be a hassle to mix, spray, and clean up. Turns out it is really easy to use. The hardest part is putting on the respirator ( buy a good 3M one from Home Depot).

My opinion is that rattle can is good for a small quick repairs, but it wont take the building abuse I subject my parts to. It seems others have good success with rattle can primer, but the stuff I was able to buy in Southern California were really worthless, in my opinion.

I hope you have better luck.
 
ezcoat

I've been using ezcoat, maroon pad, prekote clean with maroon pad (or bonami like mentioned), rinse, dry, prime, light coat. I think the ezcoat went on better then the self etch can. I tested a bunch, and have used ezcoat since. Did my vert stab and rudder so far with it. You can check pictures on my EAA page in my signature.

I'd say there is no way goo gone is residue free, I believe that's main part of the issue you are seeing.
 
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Thanks everybody for the help. A good cleaning and light coats worked perfectly. I used two light coats of self etching primer then top coated with EZ Coat. The stiffeners look great and are well protected now!
 
Your local paint supplier should sell Panel Wipe. It is a slow solvent that de greases and removes silicone prior to painting.

Maroon Scotch, wipe down with panel wipe, paint. Never had an issue and we are on a car 50/50 mix etch primer which sticks like the proverbial !

Agree with previous - flash coat, then fuller coat always best. Rattle can most of our small bits and angle - don't forget to clear the nozzle with a quick spray with the tin upside down as the last pass. Stops clogging.

3M 4251 mask is great - specifically for organic solvents. Replace every 6 months and keep in the bag sealed. Around $25 a time.
 
I am surprised metal-prep was not mentioned. It is easy and quick, just rinse with distilled water and blow dry with non-oily air.

I think Larry (wire jock) has done the best posts of hands-on research using non chemical cleaning with his Bon-Ami method.
 
Thanks everybody for the help. A good cleaning and light coats worked perfectly. I used two light coats of self etching primer then top coated with EZ Coat. The stiffeners look great and are well protected now!

Just curious, why both primers?
 
Just curious, why both primers?

I read that SES says that the EZCoat is a better topcoat, with a tougher finish that is less permeable. They say that the self etching should be used as a primer coat. Ironically, both cans say they provide corrosion resistance, but I figured it wouldn’t hurt to go with SES’ recommendation.
 
I read that SES says that the EZCoat is a better topcoat, with a tougher finish that is less permeable. They say that the self etching should be used as a primer coat. Ironically, both cans say they provide corrosion resistance, but I figured it wouldn’t hurt to go with SES’ recommendation.

Interesting, do you remember where did you found that? I did read about ezcoat being better as a primer without a top coat then se without a top coat. Since I'm using EZcoat only is why I'm curious. We are all trying to learn, thanks!
 
Your local paint supplier should sell Panel Wipe. It is a slow solvent that de greases and removes silicone prior to painting.

Maroon Scotch, wipe down with panel wipe, paint. Never had an issue and we are on a car 50/50 mix etch primer which sticks like the proverbial !

Agree with previous - flash coat, then fuller coat always best. Rattle can most of our small bits and angle - don't forget to clear the nozzle with a quick spray with the tin upside down as the last pass. Stops clogging.

3M 4251 mask is great - specifically for organic solvents. Replace every 6 months and keep in the bag sealed. Around $25 a time.

I gave up that procedure 20 years ago. I just wipe the nozzle with a rag, spot sprayed with Berryman B-12 or CRC Brakleen, and have never had a clogged nozzle or loss of pressure.
 
What's everyone using for gloves? I use a scotch-brite pad with acetone for prepping parts for P60G2, and the nitrile gloves disintegrate within seconds. I bought heavy duty gloves from HD and those also were destroyed before I finished my first part.
 
What's everyone using for gloves? I use a scotch-brite pad with acetone for prepping parts for P60G2, and the nitrile gloves disintegrate within seconds. I bought heavy duty gloves from HD and those also were destroyed before I finished my first part.

Acetone shortens the life of gloves, but I can't say that I've ever had it actually be a problem. But I'm sure gloves break down faster if you're using acetone while you scuff parts with scotch brite. I personally just scotch brite dry (I used to use scotch brite with acid etch, but after experimenting found very little practical difference in adhesion by adding the acid etch), then use the acetone separately to clean up the surfaces. I'm not sure there's a huge benefit of using acetone WITH the scotch brite, since I doubt you can get away without still having a separate cleaning step once you're done scuffing anyway. So my $.02 would be don't combine the acetone/scuff. Gloves last a long time when all you're doing is wiping parts down after the scuffing is done. You don't have to soak parts with acetone, so your gloves shouldn't be swimming in the stuff regardless of method.
 
cleaning process

There should be no need to use anything as strong as acetone for degreasing kit parts. The vapours are also bad for your health.

My suggestion to prep for priming is as follows:

1) Deburr holes and smooth/round edges as per normal practice.

2) Degrease using a specific wax/silicone/grease remover, this may be naptha based. It is friendly to nitrile gloves. Use a clean cloth or paper towels, not scotch brite. Scotch brite at this stage will spread the dissolved oil and grease into the scratched surface.

3) Remove the oxidation using maroon scotch brite with water and a few drops of mild detergent. The water will sheet off when the oxide is removed. Rinse and dry the parts.

4) Within six hours (to avoid re-oxidation) wipe down the parts with methylated spirits and clean towels just before spraying the primer.

Clean gloves should be used to handle the parts through all of the above so as to avoid contamination with body oils.
 
What's everyone using for gloves? I use a scotch-brite pad with acetone for prepping parts for P60G2, and the nitrile gloves disintegrate within seconds. I bought heavy duty gloves from HD and those also were destroyed before I finished my first part.


Whatever work has 🤣
 
I have used a diluted phosphoric acid wash with scotch brite pads, rinse, let dry then prime.
For small parts I use Alodine 1/1 bath for 5-7 minutes
I have never had any problems with flaking.

Jim Frisbie
RV 9A 950 hrs
 
Lacquer Thinner & Bonderite

I'm very satisfied with the results on the 6061 and select alclad items:

1) Clean d/o/g with acetone or lacquer thinner.
2) Bonderite alumniprep
3) Bonderite 5700 conversion coat, which is a non-chorme alodine I'm comfortable using at home.
4) SES self-etching primer.

Doesn't take long at all.
 
Process

There should be no need to use anything as strong as acetone for degreasing kit parts. The vapours are also bad for your health.

My suggestion to prep for priming is as follows:

1) Deburr holes and smooth/round edges as per normal practice.

2) Degrease using a specific wax/silicone/grease remover, this may be naptha based. It is friendly to nitrile gloves. Use a clean cloth or paper towels, not scotch brite. Scotch brite at this stage will spread the dissolved oil and grease into the scratched surface.

3) Remove the oxidation using maroon scotch brite with water and a few drops of mild detergent. The water will sheet off when the oxide is removed. Rinse and dry the parts.

4) Within six hours (to avoid re-oxidation) wipe down the parts with methylated spirits and clean towels just before spraying the primer.

Clean gloves should be used to handle the parts through all of the above so as to avoid contamination with body oils.

Whatever primer, this is a good environmental and human griendly prep process. I tried several processes and a simple scuff with a soap works. I did find Alumiprep seemed to work better for Alodine prep. I may try that new Alodine 5700. I really hate using that other stuff.
 
There should be no need to use anything as strong as acetone for degreasing kit parts. The vapours are also bad for your health.

You should qualify that statement, I agree Acetone is an aggressive solvent. It is an eye irritant, should not be ingested and may cause drowsiness or dizziness (in my experience needs large concentrations) also repeated exposure can cause skin dryness or cracking. But it is one of the least hazardous of the solvents. Can be used in small quantities (such as the uses suggested here) with only hand protection, normal splash precautions and some ventilation.
 
acetone makes me dizzy

You should qualify that statement, I agree Acetone is an aggressive solvent. It is an eye irritant, should not be ingested and may cause drowsiness or dizziness (in my experience needs large concentrations) also repeated exposure can cause skin dryness or cracking. But it is one of the least hazardous of the solvents. Can be used in small quantities (such as the uses suggested here) with only hand protection, normal splash precautions and some ventilation.

I agree Pete that there are more hazardous solvents, e.g. MEK, and that the hazards you've listed for acetone are as per the MSDS. When it comes to health and safety in the shop, I simply believe that it is worth minimising exposure by avoiding or choosing safer alternatives and wearing protective gear, according to the level of risk that we are personally prepared to take. If I ingested enough of any solvent to feel dizzy, I'd be concerned about the damage that's being done to my remaining brain cells! ;)
Cheers,
Paul.
 
Nail salons

I agree Pete that there are more hazardous solvents, e.g. MEK, and that the hazards you've listed for acetone are as per the MSDS. When it comes to health and safety in the shop, I simply believe that it is worth minimising exposure by avoiding or choosing safer alternatives and wearing protective gear, according to the level of risk that we are personally prepared to take. If I ingested enough of any solvent to feel dizzy, I'd be concerned about the damage that's being done to my remaining brain cells! ;)
Cheers,
Paul.

Walk into a nail salon sometime. Wow! Talk about fumes. Some nail polish remover is Acetone based. I wonder about the Cosmetologists working in there all day.
 
Pre-RV-10 Empennage Build

I tried rattle can primer but was never happy with the adhesion. I bit the bullet and went with Sherwin Williams P60G2. I thought it would be a hassle to mix, spray, and clean up. Turns out it is really easy to use. The hardest part is putting on the respirator ( buy a good 3M one from Home Depot).

My opinion is that rattle can is good for a small quick repairs, but it wont take the building abuse I subject my parts to. It seems others have good success with rattle can primer, but the stuff I was able to buy in Southern California were really worthless, in my opinion.

I hope you have better luck.
I just received my empennage, well, most of it, 2 weeks ago and am now really digging in to the primer issue. I had planned from previous reading to just use P60 as I figured if it's good enough for Vans then it's good enough for me.

I read elsewhere that it is hard to get a decent coat with an HVLP gun so was wondering about an auto paint sprayer ? I don't own either at this point and would probably purchase from Harbor Freight...but they seem a lot cheaper than I am used to seeing.

Any comments anyone ?

Thanks in advance.
 
I find that the primer sticks best to the aluminum that has been scruffed with the red scrotchbrite pad, etched, and alodined. My experience with self-etching primer is it will stick well to a surface that has been scruffed and cleaned with a solvent such as acetone or denatured alcohol (or isopropyl alcohol in CA). No alodine is needed. However, it's expensive to use it on the entire airplane.

I also used 2 part epoxy primer for exterior surfaces. This stuff sticks to almost anything, plastic, metal, fiberglass, and more. The surface to be primed still must be scruffed and cleaned with strong solvent to clean off an oil residues. Every paint supplier has its concoction of this 2 part epoxy primer, usually it is rebranded from a well known international paint company.

For the HLPV gun, I bought an inexpensive Eastwood brand gun which is probably a Chinese copy of a popular gun. It has two tips, one for primer and one for paint. It worked well for me in the last three years. I am in the final stage of painting my plane. The paint quality is actually dependent on the guy that shoots the paint, and not on the gun. My neighbor bought an even cheaper gun from Home Depot and the quality of his painted car is better than the paint quality on my flat surface airplane skin.

I try not to overthink it because my RV won't win any Lindy.
 
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