Original Posted By: "Jack Phillips"
Group;I've had problems painting metal parts, both steel and aluminum. Some parts will take the paint perfectly, but other times it's as if there is something on the metal that repels the paint and I get little voids and imperfections. Cleaning with hot soapy water, MEK, alcohol, or degreaser don't seem to make any difference... there are little areas that just won't take the paint.Is this maybe some silicone from a cleaning rag, or something in the pores of the metal? Any ideas?Oscar ZunigaSan Antonio, TXmailto: taildrags(at)hotmail.comwebsite at http://www.flysquirrel.net________________________________________________________________________________
Pietenpol-List: painting metal parts
RE: Pietenpol-List: painting metal parts
Original Posted By: owner-pietenpol-list-server(at)matronics.com
Oscar,I had good results using the PolyFiber products. The procedures aredifferent depending on the metal. For steel:a. Beadblast the parts to get all welding scale and any rust off. evenclean metal can benefit from beadblasting as it gives a little more "tooth"for the primerb. Clean with PloyFiber's Met-L-Solc. Prime with PolyFiber's Epoxy Primer. I find the green works better thanthe white. Once cured, this stuff is bulletproofd. Paint with whatever top coat you want. If you use their Aerothanepolyurethane, you will find it produces an extremtly hard, durable finishFor aluminum:a. Clean the parts with PolyFiber's Alkaline Cleanerb. Etch with PolyFiber's Phosphoric Acid etchc. Apply an Alodine coating. I didn't use PolyFiber's coating becausetheir's is a clear alodine and I prefer the gold alodine so you can seewhere you have missed.d. Epoxy Prime as above. The acid etch and alodine provides a finelytoothed surface and the primer just about jumps on the aluminum.e. Top Coat as above. Once the primer is on, you can use any paint you wishPolyFiber's products are very expensive (that epoxy primer is about $65 fora quart kit, which makes about 1-1/2 qts), but this is the part of yourproject that will really show. If you did a world class job on the woodworkand then the paintjob looks like crap, the whole airplane will look likecrap.JackFinally finished with structural repairs on NX899JP and starting to dofabric work. -----Original Message-----
Oscar,I had good results using the PolyFiber products. The procedures aredifferent depending on the metal. For steel:a. Beadblast the parts to get all welding scale and any rust off. evenclean metal can benefit from beadblasting as it gives a little more "tooth"for the primerb. Clean with PloyFiber's Met-L-Solc. Prime with PolyFiber's Epoxy Primer. I find the green works better thanthe white. Once cured, this stuff is bulletproofd. Paint with whatever top coat you want. If you use their Aerothanepolyurethane, you will find it produces an extremtly hard, durable finishFor aluminum:a. Clean the parts with PolyFiber's Alkaline Cleanerb. Etch with PolyFiber's Phosphoric Acid etchc. Apply an Alodine coating. I didn't use PolyFiber's coating becausetheir's is a clear alodine and I prefer the gold alodine so you can seewhere you have missed.d. Epoxy Prime as above. The acid etch and alodine provides a finelytoothed surface and the primer just about jumps on the aluminum.e. Top Coat as above. Once the primer is on, you can use any paint you wishPolyFiber's products are very expensive (that epoxy primer is about $65 fora quart kit, which makes about 1-1/2 qts), but this is the part of yourproject that will really show. If you did a world class job on the woodworkand then the paintjob looks like crap, the whole airplane will look likecrap.JackFinally finished with structural repairs on NX899JP and starting to dofabric work. -----Original Message-----
Pietenpol-List: painting metal parts
Original Posted By: Rick Holland
Re: Pietenpol-List: painting metal parts
Original Posted By: "Oscar Zuniga"
Oscar:When I built my Avid Flyer, I had to paint many aluminum and 4130 parts, notto mention fiberglass. I used a 2 part epoxy primer. Everything went great.I'd try the two part epoxy and stay away from Krylon or other primers in acan.One other problem, you have fairly high humidity in your area. You mightneed to install a moisture guard on your airline. Here at Knot-2-Shabby wehave humidity too but not as bad as San Antonio. Here is a trick I learnedfrom an old-timer... I use a filter out of the compressor at 10 feet, then Igo out 25 feet, and installed a moisture guard I bought as Sears. Then I runanother 25 feet from the mositure guard to my gun (HLVP) and it helped themoisture problem. (Don't ask me why the 25 feet-moisture guard-25 feet thingworks, I learned this trick from the paint shop here when I was spraying acustom pickup I built in the 80s... Didn't have this problema in El Paso,since there is no humidity there, but in Central Texas, wow.Are you draining the sump daily on your compressor? (A great safety measure,not to mention a way to keep excess water out oif the line.)Also, I almost always add a fish-eye additive to my paint (in addition to ahardener... in the color coat, not the primer) and the fish-eye additive isVERY GOOD for the problem you described. I've never tried these additives inanything other than enamels by the way.Last, have you used any air tools needing oil? You might have a contaminatedoil line.PLATA----- Original Message -----
Oscar:When I built my Avid Flyer, I had to paint many aluminum and 4130 parts, notto mention fiberglass. I used a 2 part epoxy primer. Everything went great.I'd try the two part epoxy and stay away from Krylon or other primers in acan.One other problem, you have fairly high humidity in your area. You mightneed to install a moisture guard on your airline. Here at Knot-2-Shabby wehave humidity too but not as bad as San Antonio. Here is a trick I learnedfrom an old-timer... I use a filter out of the compressor at 10 feet, then Igo out 25 feet, and installed a moisture guard I bought as Sears. Then I runanother 25 feet from the mositure guard to my gun (HLVP) and it helped themoisture problem. (Don't ask me why the 25 feet-moisture guard-25 feet thingworks, I learned this trick from the paint shop here when I was spraying acustom pickup I built in the 80s... Didn't have this problema in El Paso,since there is no humidity there, but in Central Texas, wow.Are you draining the sump daily on your compressor? (A great safety measure,not to mention a way to keep excess water out oif the line.)Also, I almost always add a fish-eye additive to my paint (in addition to ahardener... in the color coat, not the primer) and the fish-eye additive isVERY GOOD for the problem you described. I've never tried these additives inanything other than enamels by the way.Last, have you used any air tools needing oil? You might have a contaminatedoil line.PLATA----- Original Message -----
Pietenpol-List: painting metal parts
Original Posted By: Ron Franck
Re: Pietenpol-List: painting metal parts
Original Posted By: "Oscar Zuniga"
Possible sources1) Oil from your compressor (rings and cylinder bore getting worn)2) Are you using paper towels? Lots of brands are contaminated with Si.3) Finger prints. You wouldn't believe how much contaminant is on yourfingers!4) Contaminated shop ragsPossible solutions1) Eliminate the above2) Wipe with Prep Sol (Get it at a GOOD paint store. It's what they use inauto paint shops)3) Don't throw rocks at this one. I know it sounds totally STUPID but usethe paint you will be using on the part to clean the surface. I found thisout by accident after what you described happened several times in a row andthe finish was doing it AGAIN! I was so frustrated I literally wiped thewet paint off with a clean rag and just blasted it with another coat. (LikeI said, I was really mad). The residual paint from the wiping was wettedout by the new paint and leveled into a beautiful finish. I have pulledthis little trick several times since then when I couldn't get the surfaceclean by any normal method and darned if it didn't work every time. I don'tknow why it works and I sure don't let anybody see me do it but it hasworked. It's just embarrassing to admit I have done it. If it works foryou let me know. Heck let me know either way. It has yet to fail me whennothing else works.Hank J----- Original Message -----
Possible sources1) Oil from your compressor (rings and cylinder bore getting worn)2) Are you using paper towels? Lots of brands are contaminated with Si.3) Finger prints. You wouldn't believe how much contaminant is on yourfingers!4) Contaminated shop ragsPossible solutions1) Eliminate the above2) Wipe with Prep Sol (Get it at a GOOD paint store. It's what they use inauto paint shops)3) Don't throw rocks at this one. I know it sounds totally STUPID but usethe paint you will be using on the part to clean the surface. I found thisout by accident after what you described happened several times in a row andthe finish was doing it AGAIN! I was so frustrated I literally wiped thewet paint off with a clean rag and just blasted it with another coat. (LikeI said, I was really mad). The residual paint from the wiping was wettedout by the new paint and leveled into a beautiful finish. I have pulledthis little trick several times since then when I couldn't get the surfaceclean by any normal method and darned if it didn't work every time. I don'tknow why it works and I sure don't let anybody see me do it but it hasworked. It's just embarrassing to admit I have done it. If it works foryou let me know. Heck let me know either way. It has yet to fail me whennothing else works.Hank J----- Original Message -----