Van's Air Force
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Self etching Primer before Epoxy Primer?
- Thread starter patterson
- Start date
jsharkey
Well Known Member
Military prep would be an etch/clean with something like Dupont's 225S solution followed by chromate conversion coating (alodine) and then a zinc chromate primer prior to top coat. You could probably then tie it down at the end of an ocean pier with out corrosion worries 
Jim Sharkey
Jim Sharkey
Erik Westlund
Member
etching
the guy I've been talking to at ppg told me to use EAP9 its a ppg product that they use to prep metal before primer. I'd give them a call.
Erik
http://http://corporateportal.ppg.com/na/aerospace/default.htm
the guy I've been talking to at ppg told me to use EAP9 its a ppg product that they use to prep metal before primer. I'd give them a call.
Erik
http://http://corporateportal.ppg.com/na/aerospace/default.htm
Adhesion is my concern
I should point out that Corrosion here is not a big concern. The plane lives in a hanger and I believe it is well primered/protected inside since during the build I used alot of SEM.
My real concern now is getting good adhesion of the basecoat and no fisheyes to deal with, plus long term durability. I'm going to use DP50LF primer before basecoat, but what is the best way to prep the surface before primer is applied? My plane will be part paint and part polished, so that adds a level of difficulty to the whole deal.
Thanks again
Ron
I should point out that Corrosion here is not a big concern. The plane lives in a hanger and I believe it is well primered/protected inside since during the build I used alot of SEM.
My real concern now is getting good adhesion of the basecoat and no fisheyes to deal with, plus long term durability. I'm going to use DP50LF primer before basecoat, but what is the best way to prep the surface before primer is applied? My plane will be part paint and part polished, so that adds a level of difficulty to the whole deal.
Thanks again
Ron
kentb
Well Known Member
I used K36 on the fiberglass....
On the AL I used PPG primer after buffing with scotchbright pad. I cut the pad so that I could us it in my DA sander.
After the buffing I wiped the AL with acetone to clean and then shot the primer. Wait about 30 minutes and then shot the PPG paint.
Kent
On the AL I used PPG primer after buffing with scotchbright pad. I cut the pad so that I could us it in my DA sander.
After the buffing I wiped the AL with acetone to clean and then shot the primer. Wait about 30 minutes and then shot the PPG paint.
Kent
Ron, I had similar questions and asked PPG Tech for information about aluminum coating systems. Here's the response, make of it what you will:
____________________________
Thank you for your interest in PPG Refinish products. Aluminum may be refinished by one of the following Deltron combinations:
1. Etch primer DX1791, DPLF Epoxy, DBC, Deltron Clearcoat of choice
2. Etch primer DX1791, DPS3055, DAS3025, DBC, Deltron Clearcoat of choice
3. Etch primer DPX171, DPS3055, DAS3025, DBC, Deltron Clearcoat of choice
4. DX533, DX503, DPLF Epoxy, DBC, Deltron Clearcoat of choice
5. DX533, DX503, DPLF Epoxy, DPS3055, DAS3025, DBC, Deltron Clearcoat of choice
6. DPLF Epoxy(2 coats) DPS3055, DBC, Deltron Clearcoat of choice
These are just some of the combinations. All told there are probably another 10 more. A lot would depend on whether or not sanding is necessary (DPS3055, K36, K38 all require sanding...). The most common combination involves DPLF Epoxy somewhere in the mix. Options 1 and 4 are the most common. The rest is up to you.
A few things to keep in mind:
1. You CAN NOT apply DPLF Epoxy over DPX171 Etch primer. The only Etch products that may go under DPLF are the DX1791 Etch primer, and the DX503 Aluminum Conditioner.
2 If you decide to use the Metal Treatments (DX533 & DX503), you can not use any other kind of Etch primer as well (DX1791, DPX171)
3. DCC Concept Acrylic Urethane Single Stage may be used in place of DBC basecoat if you decide not to clearcoat.
If further assistance is required, please contact us at the Technical Service number listed below or visit our website at www.ppgrefinish.com.
PPG Technical Service office is open Monday - Friday, 8:00-6:00 EST. This office can be reached at 800-647-6050 or FAX 440-572-6772. The E-mail address is - [email protected]
____________________________
Thank you for your interest in PPG Refinish products. Aluminum may be refinished by one of the following Deltron combinations:
1. Etch primer DX1791, DPLF Epoxy, DBC, Deltron Clearcoat of choice
2. Etch primer DX1791, DPS3055, DAS3025, DBC, Deltron Clearcoat of choice
3. Etch primer DPX171, DPS3055, DAS3025, DBC, Deltron Clearcoat of choice
4. DX533, DX503, DPLF Epoxy, DBC, Deltron Clearcoat of choice
5. DX533, DX503, DPLF Epoxy, DPS3055, DAS3025, DBC, Deltron Clearcoat of choice
6. DPLF Epoxy(2 coats) DPS3055, DBC, Deltron Clearcoat of choice
These are just some of the combinations. All told there are probably another 10 more. A lot would depend on whether or not sanding is necessary (DPS3055, K36, K38 all require sanding...). The most common combination involves DPLF Epoxy somewhere in the mix. Options 1 and 4 are the most common. The rest is up to you.
A few things to keep in mind:
1. You CAN NOT apply DPLF Epoxy over DPX171 Etch primer. The only Etch products that may go under DPLF are the DX1791 Etch primer, and the DX503 Aluminum Conditioner.
2 If you decide to use the Metal Treatments (DX533 & DX503), you can not use any other kind of Etch primer as well (DX1791, DPX171)
3. DCC Concept Acrylic Urethane Single Stage may be used in place of DBC basecoat if you decide not to clearcoat.
If further assistance is required, please contact us at the Technical Service number listed below or visit our website at www.ppgrefinish.com.
PPG Technical Service office is open Monday - Friday, 8:00-6:00 EST. This office can be reached at 800-647-6050 or FAX 440-572-6772. The E-mail address is - [email protected]
Check with your paint supplier but if the surfaced is prepared as you describe, the epoxy will stick to the prepared metal. The epoxy must be coated in 24 hours. If you are going to do some body work and sanding then coat with a urethane sanding primer.
Here is some info: http://www.sherwinwilliams.com/aerospace/convprimers.asp
Ken
Here is some info: http://www.sherwinwilliams.com/aerospace/convprimers.asp
Ken
dedgemon
Well Known Member
Lot of things can work
I'm just finishing up my RV-8 paint work and I've "chosen" to do the following.
1. Clean and scuff the bare aluminum with scotchbrite pads and soap and water.
2. Clean the scuffed surface with solvent and paper towels until "completely" clean. No gray residue.
3. Shoot DP50LF primer
4. Shoot DBC base
5. Shoot 2002 clear.
5 years ago I painted my RV-9A and did basically the same prep except shot DCC single stage over the epoxy instead of the base clear.
I've had very good results with this, no adhesion issues at all.
I have shot DX1791 on inside surfaces and have noticed very poor adhesion in a couple of places (however they were not scuffed).
The modern epoxies seem to adhere really well to clean, scuffed aluminum.
I'm just finishing up my RV-8 paint work and I've "chosen" to do the following.
1. Clean and scuff the bare aluminum with scotchbrite pads and soap and water.
2. Clean the scuffed surface with solvent and paper towels until "completely" clean. No gray residue.
3. Shoot DP50LF primer
4. Shoot DBC base
5. Shoot 2002 clear.
5 years ago I painted my RV-9A and did basically the same prep except shot DCC single stage over the epoxy instead of the base clear.
I've had very good results with this, no adhesion issues at all.
I have shot DX1791 on inside surfaces and have noticed very poor adhesion in a couple of places (however they were not scuffed).
The modern epoxies seem to adhere really well to clean, scuffed aluminum.
Dave, I'm doing the same; it was #6 in the PPG advice, sans the DPS3055 sanding sealer which we don't need. Appreciate your RV-9A report.
I was also unhappy with DX1791 adhesion. Early on I shot a seat back, got a run, and elected to strip and start over. It came off way too easy, often in sheets, and all I used was a water hose and scotchbrite.
I was also unhappy with DX1791 adhesion. Early on I shot a seat back, got a run, and elected to strip and start over. It came off way too easy, often in sheets, and all I used was a water hose and scotchbrite.
If you haven't applied primer and you have already sanded you may be too late with the primer as aluminum oxidizes at a fast rate. Acid wash with an application of alodine is a fast way to get fhe bare aluminum primed quickly. For what it's worth Imron can be applied directly over alodine as are other paints if weight is a consideration. What ever you do follow the paint manufactures procedure and you should have good results. Painted RV6A and RV7 but will never paint again.
dedgemon
Well Known Member
Time helps
Dan,
I've noticed that the DX1791 improves with time (wine??). A day or two after shooting it will be really soft and not well adhered (over alcad) but will firm up and become much tougher over time. Still won't adhere great though unless scuffed. I used it inside just to bring a little zinc to the surfaces. Probably a waste of time really. The sherwin williams wash primer that I used inside of my RV-9A seemed much better. Should have stayed with it.
Dan,
I've noticed that the DX1791 improves with time (wine??). A day or two after shooting it will be really soft and not well adhered (over alcad) but will firm up and become much tougher over time. Still won't adhere great though unless scuffed. I used it inside just to bring a little zinc to the surfaces. Probably a waste of time really. The sherwin williams wash primer that I used inside of my RV-9A seemed much better. Should have stayed with it.
FWIW, instead of using paper towels and acetone, lacquer thinner or whatever, buy a 60 pack of terry cloth towels from Costco for about $18. Cloth towels cover the surface better than paper towels. These are about 16 X 18" or so and cheap enough you can toss them or use them for rags when you are done. Stewart says not to reuse them and you certainly don't want to use them if they have been dried with the softener sheets in the dryer.
Dave,
I have to agree with you on the Sherwin-Williams wash primer system. The SW E2G970 Corrosion Shield LCF Wash Primer is self etching and I have found that with a thorough cleaning process before application it has great teeth and will be hard as a rock after 24 to 36 hrs. It's not cheap, about 150.00 per gallon plus the reducer. I live in Houston and they sell this stuff to the petro chemical plants due to its adhesion properties. The recomended application is to use the epoxy filler where needed followed by the wash primer. Then apply Sherwin-Williams P30G primer surfacer/sealer, again not cheap, about 240.00 a gallon plus the reducer and hardner. The P30G is then sandable with 800 to 1200 grit and several different choices of top coat. Sherwin-Williams has teamed up with Barrett-Jackson and has a custom base coat/clear coat application Planet Color? Barrett-Jackson that should offer quite a nice overall professional finish.
I also have a real problem with the etch/alodine system. I know it's been around forever but what happens after the aircraft is built and ready for the paint shop. The etch has to be thoroughly flushed with water as its corrosive. I wonder how the etch and alodine chemicals affect wires and electronics that it may get into. With a high quality self etching primer this is not a problem. I called several A&P friends and both said the acid etch must be flushed throughly from all crackes and crevices or it will actually cause corossion. Can anyone with experience with the etch and alodine primer system weigh in here.
dedgemon
Well Known Member
No etch/alodine
I think a bunch of us are a bit leary of the whole etch/alodine thing.
My suspicion is that its been done that way mostly because it doesn't use much labor (compared to scuffing really well).
I'm much happier just scuffing, cleaning, and shooting epoxy.
Then you can pretty much shoot anything you want over the epoxy. I've had really good luck with this and it seems others have as well. Lord knows I've got enough steps in my painting system already without 2 more.
I took a painting class in 2003 (before painting my 9A) and was tought to etch/alodine just because thats the way airplanes are painted. No actual engineering or options. Fact is there are a LOT of acceptable ways to do all of this. Just read the data sheets for a bunch of different approaches. Most painters seem to stick with what has worked for them. And I can't really blame them for that. As an engineer, I would love a chance to talk to a real technical type from PPG or one of the other big paint companies.
I think a bunch of us are a bit leary of the whole etch/alodine thing.
My suspicion is that its been done that way mostly because it doesn't use much labor (compared to scuffing really well).
I'm much happier just scuffing, cleaning, and shooting epoxy.
Then you can pretty much shoot anything you want over the epoxy. I've had really good luck with this and it seems others have as well. Lord knows I've got enough steps in my painting system already without 2 more.
I took a painting class in 2003 (before painting my 9A) and was tought to etch/alodine just because thats the way airplanes are painted. No actual engineering or options. Fact is there are a LOT of acceptable ways to do all of this. Just read the data sheets for a bunch of different approaches. Most painters seem to stick with what has worked for them. And I can't really blame them for that. As an engineer, I would love a chance to talk to a real technical type from PPG or one of the other big paint companies.
David, that makes sense...it is a two part product and should need time to cure. Thanks.
dedgemon
Well Known Member
Just depends
It depends on that particular paint. You can't safely shoot just anything over these self etching primers. For instance most of the urethanes will make self-etching primers lift. Normally you would shoot a urethane sealer or an epoxy primer first.
Get the data sheet for the Valspar paint your interested in and check the surfaces that it can be applied over.
It depends on that particular paint. You can't safely shoot just anything over these self etching primers. For instance most of the urethanes will make self-etching primers lift. Normally you would shoot a urethane sealer or an epoxy primer first.
Get the data sheet for the Valspar paint your interested in and check the surfaces that it can be applied over.
