How many layers of oil paint

Lathe is coming along. One pin in the apron (part of interlock mechanism) was bent, but I was able to straighten it with the press.
I have started painting the lathe, for now it is just the apron. I tried to be good about stripping the paint and degreasing.
http://igor.chudov.com/projects/Clausing-6913-Lathe/07-Painting/
I plan on using Valspar oil paint and anti-rust red primer, which seems to be a decent, thick alkyd paint. I believe it to be oil resistant, but if anyone thinks otherwise, I would like to know.
The question is how many layers of primer and paint is best. I was planning on two layers of primer and two layers of paint. This means that it takes four days to paint something, with one day per layer due to drying time.
i
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Ignoramus11495 wrote:

If I were going to all that trouble, I'd be looking for a good 2 part catalyzed epoxy paint.
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Pete, I would like to know why you think so, just so that I can understand why epoxy is better.
i
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wrote:

Epoxy is one of the more resistant resins. Some chemicals obviously will eat it, but in normal usage its only real Achilles heel is UV radiation primarily from sunlight.
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OK, I changed my mind and I will use epoxy. I assume I need to remove the primer that I put on, which will be easy.
i
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Ignoramus11495 wrote:

Yes. You'll need a compatible primer. A two-part epoxy primer would be ideal. Randoplate or EpiBond are my personal favorites. Then a top coat to protect from UV.
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On Tue, 09 Feb 2010 09:48:41 -0600, Ignoramus11495

Maybe not, I'd ask the epoxy paint supplier. One of the outstanding features of epoxy is adhesion to metal, so you might want to. On the other hand, when I bought two part epoxy from Sherwin Williams, they recommended a primer. I don't remember what kind, but it was not water based.
Pete Keillor
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Iggy, The main advantage to any 2 part paint is that they cure, not dry. In that light, they are not stressed and resist chipping far better than any conventional paint, but whatever you use, it must be a compatible paint system from bottom 'till top. I absolutely prefer powder coating to all paints, because of durability issues and cost. If you consider the cost of all the cleaners, solvents, primer, sandpaper the cost of a powder solution is much cheaper. As an example, when I rebuilt my 13 x 40 modern SB, I did it in powder including the chip pan. Now, 7 years later, immersed in oil and other coolants and after countless cleanings, the powder coat is as good as when it was done. I have never seen any paint stand up to chips in the pan for more than a couple of years. However, I did not have the courage to put the headstock, carriage, bed or tailstock through the heat process required for the powder coat in fear of warping. If you stick to a RAL color, the powder and paints will match. Steve

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Steve, at this point I am committed to epoxy. Removing primer from the apron is not a big deal, maybe 10 minutes.
i
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Steve Lusardi writes:

This is not true; they all "cure" in that they form polymer films from monomers. Epoxy "curing" (polymerization) is triggered by the addition of a catalyst. Latex (emulsion) curing is triggered by the breaking of the emulsion caused by water or solvent evaporation. In oil paints curing is triggered by the oxygen in the air. But they all form cross-linked polymer films. They don't "dry" like mud turning into dirt. Linseed oil versus epoxy are different polymers with very different resistance to solvents, but they are both just polymers.
Paint is a superstitious item to most people. They have no idea how paint works beyond the label on the can, or what is different about various types. They think paint "dries", and that "latex" paint has something to do with rubber. For all we spend on public schooling, this is a shame, that such a practical bit of chemistry is not taught. Of course paints are an ancient item and you don't have to understand chemistry to use them, just to optimize their use.
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Richard J Kinch wrote:

Splitting hairs here,
The stuff that sets epoxy in motion is called "hardener". "Catalyst" is used in polyester and vinylester resins...
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cavelamb writes:

Yes, or "curing agent". The curing action is catalytic polymerization, which converts the resin to a thermoset material. Hence "catalyst" is an appropriate term for what an epoxy hardener is in principle.
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Richard J Kinch wrote:

Maybe. But we maintain the myth that there is a difference.
Viva la difference!
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Oil paints and latex paints, as well as conventional drying lacquers, etc., have a considerable amount of solvent that evaporates, leaving the surface of the coating in tension. They generally chip easier than two-part-curing epoxies and polyurethanes.
However, not all epoxies and polyurethanes are "100% solids." (A misnomer, but that's what they're sometimes called.) They often contain solvents, too. As for resisting chipping, two-part polyurethanes, in general, are far more chip-resistant than epoxies.
At least they were, the last time I had to research and write about them, which was a couple of decades ago.
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Ed Huntress



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On Tue, 9 Feb 2010 22:09:39 +0100, the infamous "Steve Lusardi"

Yabbut, just -try- to touch up a few small chips with epoxy or powdercoating.
Alkyd paint has worked just fine for me. Clean with paint thinner and a scotchbrite pad, then allow to dry, then paint. 2nd coat 2 days later and it lasts for years, with very easy touchup. Save the paint number and formula to your computer (and maybe a notebook) for later use.
-- In order that people may be happy in their work, these three things are needed: They must be fit for it. They must not do too much of it. And they must have a sense of success in it. -- John Ruskin, Pre-Raphaelitism, 1850
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On Feb 9, 2:19pm, Ignoramus11495 <ignoramus11...@NOSPAM. 11495.invalid> wrote:

Get some other opinions, but I would only use one coat of primer. Back when they used Zinc Chromate primer the rule was one coat, thin enough to see thru the coat. See what the paint company recommends.
Dan
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snipped-for-privacy@krl.org wrote:

The trick is to let the primer dry completely before you put on the paint. I know its hard to wait but it is the best way to do it. As far as two part epoxy paint, make sure you have proper ventilation and use a fresh air mask. The warnings on the cans are for real. I knew four different painters that used that stuff and are all dead now. I personally would not get near that stuff.
Coolant is what will make the paint peel and blister. The better the surface prep the better the paint job.
John
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    [ ... ]

^^^^^ ^^^ ^^^^     Note that does not mean a brand-new unused air mask, but an air mask which takes fresh air pumped in from a place safely away from the vapors. You pump enough air into the mask so that any leaks will be out from the mask to the surrounding air, not *anything* coming in from the paint booth. (And you probably don't want to use your compressor to provide it, because there is also "oil vapor pneumonia" to consider.) Something like a diaphragm pump would probably work well. The pressure is low, the needed air flow is only medium.
    And *absolutely* *positively* don't paint in any part attached to the house and keep the wife and kids away until the job is done.

    That I can understand.
    Good Luck,         DoN.
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I will read the labels and follow.
Are you guys talking about spray painting with a spray gun, or does what you say apply to brush painting?
If this epoxy is that bad, I will wait until summer to apply it, when I can do it with the garage open.

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On Tue, 09 Feb 2010 23:46:49 -0600, Ignoramus11495

Hmmm. Ig, summer will be better because of cure times anyway, and good ventilation is a necessity. I painted mine in a homemade spray booth, really just a poly sheet room with a 500 cfm exhaust blower, in the basement. I did use a respirator, more for the solvent MEK than the epoxy.
I worked with epoxy for several decades on a daily basis with local ventilation, no respirator. One of the primary concerns with epoxy is the minute amount of residual epichlorohydrin, which is a sensitizer. The hardeners, usually amines, can be very nasty. Some of the amines I worked with are worse than lye if you get them in your eyes.
Some of the precautions above sound a lot more appropriate for two part urethane systems, which are a whole different class of hazard, since urethanes are a reaction product of isocyanates and polyols. The isocyanates will kill you. I think they're grossly overstated for epoxy. Do a search on cold molded boats and you'll see massive amounts of handwork with epoxy. Keep in mind that the damned stuff is extraordinarily sticky and a mess to clean up.
Just stick to your plans of following the label precautions and you should be fine.
Pete Keillor
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