Van's Air Force
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Acid etch instead of scotchbrite?
- Thread starter Lionclaw
- Start date
JanRV6UK
Well Known Member
Well .. I wipe all alu with acid etch using Scotchbrite .. then rinse with lots of water .. you see the water just 'sheet off' ... the difference is so easy to see ... you remove all grease and any oxidation .. I use a aircraft grade etch primer - which does not come off with MEK after it has fully cured ...
az_gila
Well Known Member
Acid etch?
Where is the acid in the rattle can primers?
Here is the Home Depot one's MSDS -
http://www.homedepot.com/catalog/pdfImages/aa/aa8d8a7b-f26a-4b45-b364-20ab8464716d.pdf
No mention of acid here either -
http://www.homedepot.com/p/Rust-Ole...-Aerosol-Primer-254170/202531910#.UiEJe53n-Uk
It seems like it has more cleaning solvents built in, that's all.
Where is the acid in the rattle can primers?
Here is the Home Depot one's MSDS -
http://www.homedepot.com/catalog/pdfImages/aa/aa8d8a7b-f26a-4b45-b364-20ab8464716d.pdf
No mention of acid here either -
http://www.homedepot.com/p/Rust-Ole...-Aerosol-Primer-254170/202531910#.UiEJe53n-Uk
It seems like it has more cleaning solvents built in, that's all.
JanRV6UK
Well Known Member
I also wonder if all so called 'acid etch' are created equal ... This is what I use http://ecocleanavantichemicals.shop033.com/p/8269548/20l-deoxidine-624.html
Not that I buy it from Australia .. But look for the data sheet. it has some very strong stuff in it ... Deoxidine 624 I have had small small parts in the bottom of my small plastic bath I use .. taken straight out .. after being in it for 15 or 20 min while rubbing the larger stuff with Scotchbrite .. when rinsing with water ... the water just flows on the alu in a completely different way .. it removes all traces of grease and any oxidation
Not that I buy it from Australia .. But look for the data sheet. it has some very strong stuff in it ... Deoxidine 624 I have had small small parts in the bottom of my small plastic bath I use .. taken straight out .. after being in it for 15 or 20 min while rubbing the larger stuff with Scotchbrite .. when rinsing with water ... the water just flows on the alu in a completely different way .. it removes all traces of grease and any oxidation
bruceh
Well Known Member
You definitely need the mechanical scratching of the surface with the scotchbrite pad to get a good surface to prime.
Fill a spray bottle with 50/50 alumiprep and water. Spray it on, and go at it with the scotchbrite pad. You don't necessarily have to get every nook and cranny, but definitely do the thorough once over with the pad. Rinse and make sure the water doesn't bead up on the surfaces. I let it dry then give a quick wipe down with acetone on a paper towel before shooting on the primer. You'll see with the acetone wipe down that there is still some residual gunk on the pieces that needs to be taken off. If you have lots of pieces that you are doing, and you don't want to get them mixed up, you may want to remark them with a blue sharpie before hitting them with the primer. Be sure to wear gloves when you handle the pieces.
Fill a spray bottle with 50/50 alumiprep and water. Spray it on, and go at it with the scotchbrite pad. You don't necessarily have to get every nook and cranny, but definitely do the thorough once over with the pad. Rinse and make sure the water doesn't bead up on the surfaces. I let it dry then give a quick wipe down with acetone on a paper towel before shooting on the primer. You'll see with the acetone wipe down that there is still some residual gunk on the pieces that needs to be taken off. If you have lots of pieces that you are doing, and you don't want to get them mixed up, you may want to remark them with a blue sharpie before hitting them with the primer. Be sure to wear gloves when you handle the pieces.
XOverZero
Well Known Member
PreKote
Ditto here...scotchbrite and PreKote. Another plus is not having to wipe with acetone. In fact, the directions specifically say do not use any solvents, just rinse with clear water. One less nasty to deal with. I air dry the parts, then wipe off any residual drops with a Kimwipe. SEM then adheres very well.
Ditto here...scotchbrite and PreKote. Another plus is not having to wipe with acetone. In fact, the directions specifically say do not use any solvents, just rinse with clear water. One less nasty to deal with. I air dry the parts, then wipe off any residual drops with a Kimwipe. SEM then adheres very well.
I used scotchbrite, acetone, and then marhyde for my interior during my 9 years or building. Very durable with no place that it scratched or wore. Before first flight sprayed entire interior with PPG Concept polyurethane. Sprayed it right over the Marhyde with just a scotchbrite rub. Seven years and 600 hours it still looks like new. No signs of Marhyde underneath letting loose.
Exterior done with scotchbrite, acetone, then PPG etch primer with Concept polyurethane over top. Also still looks new.
Exterior done with scotchbrite, acetone, then PPG etch primer with Concept polyurethane over top. Also still looks new.
Having painted some 500 airplanes, (now retired)
FWIW, I have had problems with "etch primers" and I have tried several different ones.
My recomendations, FWIW, Acid etch & scotch pad, clean water rinse, air dry, alodyne, applied with a sprayer, air dry, Epoxy primer, Top coat, check the Mfg. recomendations for "Open Time" on the primer. Do NOT wipe with any solvent. A clean enviorment is always best.
It is best to do the steps in quick succession to eliminate the possibility of contamination.
I am sure this will meet with some discussion, it is the process that has given the best results for me, and I have tried them all.
Dick
FWIW, I have had problems with "etch primers" and I have tried several different ones.
My recomendations, FWIW, Acid etch & scotch pad, clean water rinse, air dry, alodyne, applied with a sprayer, air dry, Epoxy primer, Top coat, check the Mfg. recomendations for "Open Time" on the primer. Do NOT wipe with any solvent. A clean enviorment is always best.
It is best to do the steps in quick succession to eliminate the possibility of contamination.
I am sure this will meet with some discussion, it is the process that has given the best results for me, and I have tried them all.
Dick
KTM520guy
Well Known Member
This is the best way. I do a couple of things slightly different. I don't dry between the etch rinse and the alodine and right before priming I will clean the surface with a lint free cloth and MEK. I don't like for an alodined plane to sit to long before priming. No more than 24 hours. That being the case, I will not wash a plane on a Friday.
JanRV6UK
Well Known Member
Can you elaborate please
Hi Dick
Can you elaborate what your problem have been with Etch Primers ?
Hi Dick
Can you elaborate what your problem have been with Etch Primers ?
az_gila
Well Known Member
Don't know about Dick's comments, but the Aviation Finishes documentation for DuPont doesn't even list an etching primer -
http://pc.dupont.com/dpc/en/US/html...E-R4112_Aviation_Finishes_System_Overview.pdf
Jan,
I have had problems with SW etch primer, poor adhesion, a case in point, SW paid me to repaint after there TECH. PEOPLE ADMITTED THERE WAS AN ISSUE WITH THE PRIMER. In fairness to the Mfg. this was a number of years ago. Had similar issues with other brands of wash primer. As a result I disposed of any and all inventory of wash primers, never to be used again.
As I said earlier, this was a number of years ago and perhaps technology has improved???? but why take a chanch when you have a proven process?
Hope this helps,
Dick
I have had problems with SW etch primer, poor adhesion, a case in point, SW paid me to repaint after there TECH. PEOPLE ADMITTED THERE WAS AN ISSUE WITH THE PRIMER. In fairness to the Mfg. this was a number of years ago. Had similar issues with other brands of wash primer. As a result I disposed of any and all inventory of wash primers, never to be used again.
As I said earlier, this was a number of years ago and perhaps technology has improved???? but why take a chanch when you have a proven process?
Hope this helps,
Dick
KTM520guy
Well Known Member
Back in the 1970's Cessna and Piper both started using self-etching primers to speed up the painting process, thus saving money. If you follow the spec for the primer all is good. Self-etching primer needs more time before it's ready to paint over. You need time for the acid to evaporate out of the primer. Some of the management types did not like seeing primed planes sitting around with no one working on them and ordered them painted. In some cases they were lucky and the primer was good to go. In other cases, the primer was not ready. The paint that was applied trapped the remaining acid and corrosion started to develop. Cessna and piper both bought a bunch of repaint jobs. So much for saving money.
In my experience, self-etching primers have poor adhesion compared to regular primers. Every time I have have used self-etching primer, some primer comes off. It has not mattered the age or type of aircraft or even the brand primer used.
longranger
Well Known Member
"Dry" Does Not Mean "Cured"
I've had no problem with Duplicolor self-etching primer AS LONG AS I LET IT CURE FOR A FEW DAYS AT ROOM TEMPERATURE. If I don't wait, it can be knocked off like you'd painted a piece of Teflon.
After the cure period, I can dimple the parts without loosening the primer.
My prep process is to scotchbrite with Dawn soap suds until there's no beading of the rinse water, then towel dry before spraying.
I've had no problem with Duplicolor self-etching primer AS LONG AS I LET IT CURE FOR A FEW DAYS AT ROOM TEMPERATURE. If I don't wait, it can be knocked off like you'd painted a piece of Teflon.
After the cure period, I can dimple the parts without loosening the primer.My prep process is to scotchbrite with Dawn soap suds until there's no beading of the rinse water, then towel dry before spraying.
Dean Pichon
Well Known Member
I typically see aluminum tape used to seal openings against intrusion of paint remover, etching solution, or conversion coating. Riveted seams are not protected.
