Bare aluminium bike frame – etch or epoxy?
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When I paint aluminium/aluminum items that have been media blasted, if the surface is fine enough (ie. from Soda), we’ll use 2-3 coats of PPG D831 Etch Primer, a 15 min flash off and then straight to basecoat followed by clear. Otherwise you can do DG straight over the etch as well.
PPG do recommend a WOW primer over the top of the etch before base (or a sealer such as D825), but we’ve never had any issues and/or returns of any items painted in this ‘etch to base’ method. And I’m talking about things that get a lot of wear and tear including wheels and brake calipers. I actually prefer not having to apply a primer after the etch as it keeps my material build down.
Alternatively, you can get the frame powdercoated, and then base right onto the PC after it has been scuffed with a 500 grit dry pad.
PS> MIPA also have a 1K etch that you can base right onto.
If it was me I would use proper etch as I call it (not 1k stuff that comes in aerosol) then wet on wet and base and clear, simples.
We do alot of audis (aluminium panels) and they recommend the spies 4075 which is proper etch and on new panels and repairs and for any warrenty corrosion work we have to use the epoxy primer which can be used as an etch sanding and non snding surfacer just takes ages before you can do anything with it sand or recoat it. Ive always maintaned that etch should never be painted straight over with waterbase.Another thing if the aluminium has sat around bare for a while and handled alot I would chuck it in with another job and bake it before Id clean and paint it.
[quote=”InvictaRefinish” post=25483]If it was me I would use proper etch as I call it (not 1k stuff that comes in aerosol) then wet on wet and base and clear, simples.
We do alot of audis (aluminium panels) and they recommend the spies 4075 which is proper etch and on new panels and repairs and for any warrenty corrosion work we have to use the epoxy primer which can be used as an etch sanding and non snding surfacer just takes ages before you can do anything with it sand or recoat it. Ive always maintaned that etch should never be painted straight over with waterbase.[/quote]Agreed…we don’t use aerosol primers except the PPG G5, which is a 1K aerosol speifically used for rub throughs. And the MIPA product isn’t an aerosol. It comes in a tin.
And, we’re using Delrton GRS which is solvent-based. As mentioned, never had any problems basing straight onto the 2K D831 Universal etch after a 15min flash off. Often though, I will coat the etch with D825 before base as it is a tintable surfacer/primer.
Thanks for all the replies
[quote=”InvictaRefinish” post=25484]Another thing if the aluminium has sat around bare for a while and handled a lot I would chuck it in with another job and bake it before Id clean and paint it.[/quote]
Yes, I used to do that back when I was doing a lot of wheels, and clean them immediately before priming.
Waiting to see what my DeBeer guy comes up with on the etch. I’m hoping for another free sample… :whistle:
Well it’s been a while, but I finally received the bike frame the other day, along with a major change of direction – he wanted it satin black instead of lime green!
After chatting with Peter from DeBeer about my concerns of keeping the film build as low as possible, he suggested one coat of well reduced epoxy, left to sit for an hour, then two coats of 2K primer/sealer. I had planned to let this flash and go wet on wet with the (solvent) base, but ran out of time. The next morning I gave the primer a quick sand down and gave it two coats of black base, then my cocktail clearcoat.
From experiments in the past I’ve found I can get a great satin finish with good durability by mixing 10% of DeBeer 8-214 scratch resistant clear into their 1-105 matt clear. Two coats of that later and it was looking good.
For those of you into your MTB’s the bike itself is a Specialized Demo 8, 2012 model. Apparently £5k worth of bike, with just the aluminium and magnesium frame being £2.5k of that! Even though it was brand new he wanted it painting so it was unique. He’s sending me some photo’s when it’s built up, then he’s off over to Whistler with it to start his new job.
Some pics I took along the way:
[IMG]http://i321.photobucket.com/albums/nn385/Duluxdude/Work/Robs%20MTB/P1010706Large.jpg[/IMG]
[IMG]http://i321.photobucket.com/albums/nn385/Duluxdude/Work/Robs%20MTB/P1010709Large.jpg[/IMG]
[IMG]http://i321.photobucket.com/albums/nn385/Duluxdude/Work/Robs%20MTB/P1010710Large.jpg[/IMG]
[IMG]http://i321.photobucket.com/albums/nn385/Duluxdude/Work/Robs%20MTB/P1010712Large.jpg[/IMG]
[IMG]http://i321.photobucket.com/albums/nn385/Duluxdude/Work/Robs%20MTB/P1010714Large.jpg[/IMG]
[IMG]http://i321.photobucket.com/albums/nn385/Duluxdude/Work/Robs%20MTB/P1010715Large.jpg[/IMG]
[IMG]http://i321.photobucket.com/albums/nn385/Duluxdude/Work/Robs%20MTB/P1010716Large.jpg[/IMG]
[IMG]http://i321.photobucket.com/albums/nn385/Duluxdude/Work/Robs%20MTB/P1010717Large.jpg[/IMG]
i like it Andy! those are some real nice bikes. Pics assembled would be cool.
Thanks Ryan.
I was surprised how little it weighed too! I put a dozen or so bolts into a plastic bag for safe keeping, and the bag weighed more than the bolts 😆 The magnesium parts almost felt twice as heavy with primer and paint on.
Unfortunately the guy has contracted Glandular Fever, so may not be building the bike up just yet. It’s also ruined his chances for the job in Canada. Doctors have told him he can’t ride for 6 months 🙁
Nice. Good job
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