Painting over anodize?


Is any special preparation require when painting over a newly oxidized steel
surface?
Will either fine roughing up with 400 grit work, or using a regular oxide
primer?
Or...?
Thanks.
Reply to
Gone Fishin'
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However, here are some rules. Don't paint over mill
on it and that will lift on its own, so it must be
shot blasting to white metal is much better.
exists and cannot be removed. The use of muratic
converters. In the case of chemical use, the chemicals need
After all of these processes, you have a short
sets in. Depending on prevailing conditions, that
Use of a passivating metal treatment will extend the window considerably and will also aid wetting and adhesion significantly.
Reply to
Don Foreman
. After all of these processes, you have a short
rrosion sets in. Depending on prevailing conditions, that
Whether you just neutralize the acid and wash, or whether you use phosphoric acid, you should apply the primer as soon as the surface is really dry. Tests done on aluminum treated with fpl =A0pretreatment, found that the bond strength was highest with immediate application of the paint. Just sitting around for a couple of hours produced lower bond strengths. No corrosion involved. Just airborne contaminates.
Dan
Reply to
dcaster
Your question is far too vague, but painting steel is not rocket science. However, here are some rules. Don't paint over mill scale or rust. If the steel has not been shot blasted, it still has mill scale on it and that will lift on its own, so it must be removed. Wire brushing and grinding is slow and ineffective for this. Sand and shot blasting to white metal is much better. Purpose rusting helps to lift the mill scale and makes blasting faster. If rust exists and cannot be removed. The use of muratic acid works well. If that cannot be used, then it can be converted with converters. In the case of chemical use, the chemicals need to be washed away with water and neutralized with a soda and then washed again. After all of these processes, you have a short window of time to get the first coat of etching primer applied before corrosion sets in. Depending on prevailing conditions, that window is between 20 minutes and 2 hours. Whatever paint system you elect to use, you must follow the manufacturer's directions verbatim. Do not take short cuts. The first paint applied is critical to the paint scheme being applied and all the other ones which may occur later on. You probably think I'm really anal about this and well over the top. I am not. Take short cuts and you will learn the hard way. Many times these rules are not followed, but only in the cases where the failure will occur on some one else's dime or ignorance is present.. Steve
Reply to
Steve Lusardi
often use one as cheap insurance even on white metal.
Uh...yes.
I use a couple of PPG/Ditzler products. DX579 metal cleaner contains phosphoric acid and a detergent. DX520 metal conditioner (used after DX579 if at all) contains phosphoric acid, zinc oxide, nickle nitrate and nitrobenzenesulfonic acid sodium salt. The cleaner (DX579) removes oils, waxes and light rust. The conditioner (DX520) leaves a passivating coating of zinc phosphate.
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However, here are some rules. Don't paint over mill
scale on it and that will lift on its own, so it must
and shot blasting to white metal is much better.
rust exists and cannot be removed. The use of muratic
converters. In the case of chemical use, the chemicals
again. After all of these processes, you have a short
corrosion sets in. Depending on prevailing conditions, >>>that >>>window is between 20 minutes and 2 hours. >> >> Use of a passivating metal treatment will extend the window >> considerably and will also aid wetting and adhesion significantly.
Reply to
Don Foreman
Don, Are you referring to phosphoric acid compounds as passivating treatment? I often use one as cheap insurance even on white metal. Steve
However, here are some rules. Don't paint over mill
on it and that will lift on its own, so it must
shot blasting to white metal is much better.
rust exists and cannot be removed. The use of muratic
converters. In the case of chemical use, the chemicals
again. After all of these processes, you have a short
corrosion sets in. Depending on prevailing conditions,
Reply to
Steve Lusardi
Confirmed: sanding these parts 24 hours after spraying 2nd coat and the paint is not dry. Gummed up the sand paper.
Boy, does this Rustoleum paint dry slowly... It says 48 hours, but at this rate it looks like it will be longer.
Is Krylon a better choice? Or...?
Thanks.
Reply to
Gone Fishin'
Rustoleum is good paint. There are other heavy-duty enamels, from the majors, but most straight alkyds are going to take a long time to dry hard. That's just enamel. Rustoleum probably is slower to dry than most. In many applications, they don't use a second coat. It's better to use a good primer, and then the top coat will lay on a lot thicker than each coat used without primer. Get a compatible primer made for use with the enamel.
There are a lot of industrial-type paint systems out there today, including several polyurethane systems that are tough and that produce a nice finish. Probably the toughest is two-part polyurethane, which comes in brushable versions. Don't touch the spray-coat versions unless you study it well. It's highly toxic and you can't protect yourself with just a respirator. But the brush-on is safe.
I like plain, old-fashioned enamel. But I use it with primer.
-- Ed Huntress
Reply to
Ed Huntress
Rustoleum takes at least a week to get as hard as it ever will, which isn't very.
There are respirator cartridges that are NIOSH-rated for urethanes. The more significant issue is getting a good face-to-respirator seal.
Reply to
Don Foreman
Can you recommend another brand of spray-can paint that you like better?
Thanks.
Reply to
Gone Fishin'
You go first. I'll watch.
-- Ed Huntress
Reply to
Ed Huntress
I should wait for Don's opinion, since you asked him, but my opinion is that none of them are worth the powder to blow them to hell.
If I need to spray paint on something, I use one of my spray rigs -- even the little Badger "spray can," with a spare tire for an air supply, on little jobs. It's better than spray cans, and a lot cheaper after you've done a few jobs. Those Badger thingies are cheap.
You can get much better paints in a regular can than the junk they put in spray cans.
-- Ed Huntress
Reply to
Ed Huntress
I concur.
Reply to
Don Foreman
On Wed, 2 Sep 2009 06:43:34 -0700, Ed Huntress wrote (in article ):
All I see by Badger is the air brushes:
Can you point to the Badger "spray can" device?
Thanks.
Reply to
Gone Fishin'
I've painted several cars with PPG/Ditzler basecoat-clearcoat urethane. No problems. I renewed the cartridges after each job.
Reply to
Don Foreman
For very small projects (this one I'm doing is about 10-12 square inches), can you buy small quantities of quality paint? Where?
Thanks.
Reply to
Gone Fishin'
This is the newest version, I guess. It's a little fancier-looking than mine, but it looks like it's still the same old suction-type atomizer device:
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Mine has served me well for around 35 years. I got the tire converter for it, which I think came with it when I got mine. But I use it most often with a little compressor. The cans of "Propel" work well, too.
BTW, if you have any metalworking tools, these things are simple as can be to make, from an old screw-top jar and a couple of aluminum rod scraps. But you need one that works from which to take the proportions and get them right.
-- Ed Huntress
Reply to
Ed Huntress
OK. Have you taken an IQ test since you did that, to see if the numbers still hold up?
Just so people are aware that ordinary paint respirators are NOT up to the job. From there, they should research it thoroughly.
-- Ed Huntress
Reply to
Ed Huntress
Buy the smallest cans you can get and learn how to seal a paint can well after using it. I have alkyd resin cans that are 20 years old and the paint still goes on and dries just fine.
-- Ed Huntress
Reply to
Ed Huntress
BTW, I see that the tire/Propel adaptor and the hose come complete with the sprayer on the "blister pack" offer here, for $17.99:
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If you find that the enamel you're using is too thick to spray well in a little sprayer, I suggest using this trick before adding thinner: Heat a saucepan of water and hold the assembled and filled sprayer in the hot (not boiling; maybe 150 deg. F) water for a couple of minutes. Then wrap it in a dishtowel while spraying. Watch out for water drips coming off the bottom of the jar when you spray.
This works with really heavy paint and modest (40 psi or so) spraying pressures, which is all you should use with that rig -- especially if you're using a tire for air.
-- Ed Huntress
Reply to
Ed Huntress

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