Ok you back yard painting guru's here is what I need!
Got a new panel made for myu bay dor just like the one the dealer had made before I bought the bus. I damaged this on e when I drove over a tree root in the dark woods of Sertoma one night! That's another story! Anyway, my friend did an awesome job for the new panel and I'm about to glue it in place.
Question, it's aluminum as was the first one, and it needs to be painted after it's on the bay door. What do I need to do to prep this panel for the paint to adhere? I have cleaned the old part where it is to be glued and I have the glue, along with 1x2's strips of wood and clamps to hold it in place for 24 hrs.
What is the best grit/s sand paper to use and what is the best primer?
Thanks as always....
Ace
Buses, Bluegrass & Babes! (not necessarily in that order)
Ace,
Should that be Babe without the 's" AKA Susan?
When we painted the new aluminum skin on our bus (almost 10 years ago), we bought an etching solution that was applied first, then a primer that was made for aluminum. Go to a local autobody paint store and they can fill you in on whats available and how to use it. Jack
I use Southern Polyurethanes Epoxy Primer regularly for priming aluminum. DA with 80 grit, degrease and prime. No etching necessary. It is an awesome Epoxy Primer.
absolutly correct, if you rough the panel up, do not use etch primer, etch is designed for smooth surface only.
Ray D
Buddydawg is correct in that you do not have to etch if you use an epoxy primer. Then wet sand with a rubber pad using 400 grit and you will be ready for paint. You sand until the shine is off ( use a small squeegee ) and the 80 grid scratches are filled and smooth. Ask your local body shop supplier for the squeegee and the sanding pad.
That said, I am old school and an leaning toward cheap insurance and to etch anyway. It is a very simple and inexpensive process. Then epoxy prime and paint.
Another thing, if you are painting the panel on the bus, be sure to mask off the entire bay opening and rubber so you don't get overspray everywhere and dirt blowing out from the bay. Good Luck!
Thanks guys! I will be going to the local paint supplier soon!
Another question! Since this is relatively small, can I just use a touch up gun and if so what is the best recommended air pressure?
Also can I ask for the paint in a pint instead of a quart?
Annndddd.... what's the best mix ratio such as 50/50 60/40 etc.?
This is going to be base coat clear coat application to match the rest of the bus if that helps!
Thanks
Ace
Rough the panel up with 80 grit????? Are you kidding? What happens when someone wants to polish down the road?? A light scuff with red Scotch brite pad is plenty. Take it from one who has painted small airplanes all the way to airliners. Aluminum is aluminum.
The correct way to prep aluminum is. Etch, Alodine, and prime.
1.) Clean it with DuPont Super clean (pre-sanding) silicone and wax remover followed by some MEK if you want using clean sanitized flannel rags.
2.) Scotch Brite the panel until all gloss is gone. Clean again as above until no black is shown on the rags.
3.) Etch aluminum with Dupont AlumiPrep acid etch. Mix with water per container and spray on and let stand for about one and a half minutes. Rinse with plenty of water, Deionized is preferred but tap is OK. allow to dry completely
4.) Alodine with Dupont alodine mixed per container. Let stand on surface again for about a minute and a half. Rinse again with lots of water and a gold tint should be visible if done correctly. This process is called a conversion coating and will pay huge dividends with paint adhesion and corrosion prevention down the road. It will stop filiform corrosion from occurring under paint. You know those little worms under the paint.
5.) Tack rag and prime with primer of your choice/ zinc chromate is the easiest, cheapest and plenty good, just a couple of light coats will do. I have pulled Curtis P-40 crashed Warhawks out of Russia that showed no signs of corrosion because of the proper treatment and zinc chromate. In fact the chromate was still as good as the day it was sprayed. These airplanes were outside in the forest since WWII.
A word to the wise: never let MEK come into contact with powdered alodine it will explode. Seen it happen.
QuoteRough the panel up with 80 grit?Huh? Are you kidding? What happens when someone wants to polish down the road?? A light scuff with red Scotch brite pad is plenty. Take it from one who has painted small airplanes all the way to airliners. Aluminum is aluminum.
The correct way to prep aluminum is. Etch, Alodine, and prime.
No I'm not kidding, if someone wants to polish it down the road they should not be painting it now. Aluminum is aluminum but every paint system is different. The correct way to prep aluminum depends on the system you are going to use to paint it. Dupont may require the use of the steps you laid out, so be it. Southern Polyurethanes recommends a different application. Take this from me someone who has painted motorcycles, boats, cars and to top it off a crap load of aluminum. I try not to take up with the squabbling around here but I can assure you there are many ways to "correctly" prep and paint aluminum. Now you you are entitled to do it your way and share it with the world but don't tell me the "correct" way, when I can promise you my way is just as effective.
You should ALWAYS refer to the tech sheets of the products that you use. Note the warning from SPI about etch and metal treatments and the use of their products at the end of their tech sheet.
Uses for SPI Epoxy:This epoxy is one of the finest available and it is great for use on any type of metal or
aluminum if properly cleaned. This epoxy eliminates the need for an acid-etch primer.
Use this epoxy on bare fiberglass or SMC before applying body fillers or 2K primers for
best long-term results.
Prepping the Surface:Metal or Aluminum must be clean of all rust and oils and any films. Never clean metal
with lacquer thinner or reducers of any kind. Raw metal of any type is always cleaned
best with a waterborne wax and grease remover such as SPI's part # 700-1. This is most
important for prepping aluminum and sand aluminum or metals with 80 grit DA paper.
Spraying:Spray two wet coats for normal applications. For special projects such as restorations
Spray one coat and let it flash about 10-30 minutes at 70° degrees or higher. Then spray
second coat for maximum corrosion protection. If one coat of epoxy is used wait 60
minutes before painting.
This epoxy does not need to be sanded if painted over within 7 days. Always paint or
primer over the epoxy within 7 days. After 7 days the epoxy should be sanded and recoated
with epoxy for best adhesion.
Body Fillers:On any restoration it is always best to apply the body filler over the epoxy rather than
bare metal for best adhesion and corrosion protection. If one coat of epoxy is used then
the body filler can be applied in 60 minutes. When applying two coats of epoxy, wait
over night before applying the body filler. The epoxy does not need to be sanded before
applying the body filler.
Wet and Dry Sanding:If for some reason you need to sand a large area of epoxy, the epoxy will dry sand best
after 12 to 16 hours. Wet sanding with moderate pressure can be done after 60+ minutes.
To use as a Paint Sealer:To use the epoxy as paint sealer, reduce 10-50% with the proper temperature range
urethane reducer (this is very important). Spray one wet coat ONLY, let it set 60 minutes
and apply paint. For sealing of a potential problem paint job, apply two coats of epoxy
with proper flash times between coats and let it set over night before painting.
Pot Life:24-48 hours depending on humidity and temperature (sealed container)
Precautions:
NEVER use SPI Epoxy over a Soda Blasted vehicle, Acid
Etch/Wash Primer, Rust Converter or other Metal
Treatments. NEVER!
Is there a trick to sanding around the rivits? I sanded some around the cap on my bus using a 4 1/2" grinder with a wire wheel. The cap is steel and the rivits are aluminum. I was not happy with the results. How should it be done?
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I try not to take up with the squabbling around here but I can assure you there are many ways to "correctly" prep and paint aluminum. Now you you are entitled to do it your way and share it with the world but don't tell me the "correct" way, when I can promise you my way is just as effective.
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I don't care for squabbling either. I do think that 80 grit is a bit more akin to a chip sealed road surface than something I'd want rubbed on my bus.
I don't know much about a lot of things but as an aircraft painter that has his work in the Smithsonian Air and Space Museum and have been doing it all my life I can truly say I am right. The boys that pay 50 million for their jets made of Aluminum want it done right because they travel at 600mph in all sorts of conditions including rain snow and ice and it sucks when the paint comes off.
No disrespect intended here you probably have forgotten more about buses than I will ever know.
Ace, One word KRYLON. At Wally world. Tom Y
BarnOwl. The wire brush is way to stiff and will scratch the metal which should be filler and sanded smooth. Get a red scotch brite pad and sand each and every rivet and the surrounding metal until there is no shine. Yes, it is a ton of work but the paint just won't stick if there is any dirt or smooth paint. It is a lot easier to sand now that to strip the peeling paint and fix later !!
And I just learned something thanks guys. I didn't know you shouldn't epoxy over etched alum!
And with all this great advice Ace. You better :) lay an, "@$# Bustin' Shine" on that bus !!!!
Gee the area I'm doing is only 18-20 inches by about 40 inches. Its down at the bottom of a bay door and I only want it to blend with the rest of the bus which wasn't done what I would call professionally but well done none the less!
Thanks again...
Ace
Hold on a second. Ace said he was going to GLUE the panel on the door. If that is the case why isn't the panel painted in a friendly environment "before" it is glued on the bus? Inquiring minds and all that. Who wouldn't skip the masking process if the could?
I have sprayed a coach outside in the dirt road and all I did to keep dust down was sprinkle the crap out of the area around the coach really well and painted in the early morning. No dust, bugs, sticks or small birds in the paint. I know, I wouldn't have believed it either but I got a superb job from really cheap DuPont paint.