What's your paint prep process?

I have never had Rustolium fully cure in less that 3 weeks at room temp (around 65°F) with low humidity (under 35%). Yes it dries hard enough to handle in just a few hours, but 3 weeks to a month to fully harden. Once fully hard it is a tough paint. Make sure the surface has something for the paint to hold on to. A nicely machined surface is hard to get a grip. Sand blasted makes for a high grip even finish.

With all of that said. The part can not be to clean.While and after cleaning do NOT toutch it with bare hands, you will leave an oily fingerprint everywhere you touch it. Also be conscious of where you set it down to be sure that that surface is also clean.
 
Bare metal needs etched. I used to use a DuPont etchant which is no longer available, but Pontiac 428 put me onto ospho which is apparently very similar. Phosphoric acid. Just follow instructions wire brush or scotch brite the white residue Off. Clean with isopropyl alcohol. Dry with compressed air. Watch and see if oils come out of porous castings. If so more isopropyl, more air. Then epoxy prime And paint. Works pretty good for me.
 
rabler said:
I would add that many of the metal paints take *weeks* before really hard, so I would not be surprised if they came loose in a couple of days. This is especially true if not kept fairly warm. Heat lamps can help.

I normally clean with mineral spirits followed by a wiped down with IPA just before painting. Acetone flashes off so fast I find I can't make any progress before its gone. But I doubt that matters as long as you're doing a decent job.
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Mineral spirits leaves behind an oily film. IPA doesn't, but it's not the most aggressive cleaner.
 
GT-6 Racer said:
Bare metal needs etched. I used to use a DuPont etchant which is no longer available, but Pontiac 428 put me onto ospho which is apparently very similar. Phosphoric acid. Just follow instructions wire brush or scotch brite the white residue Off. Clean with isopropyl alcohol. Dry with compressed air. Watch and see if oils come out of porous castings. If so more isopropyl, more air. Then epoxy prime And paint. Works pretty good for me.
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Klean-Strip 1 Gal. Concrete Etch, Metal Prep and Rust Inhibitor GKPA30220 - The Home Depot

For Pro's and DIY'ers, Klean-Strip is the leading brand of solvents, thinners, removers, and cleaners that are dependable for reliable results. Klean-Strip Concrete and Metal Prep does the job of three
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This stuff is phosphoric acid, and works great. It eats off rust quickly, too. Dilute with water, it's quite strong full strength.
 
Flyinfool said:
I have never had Rustolium fully cure in less that 3 weeks at room temp (around 65°F) with low humidity (under 35%). Yes it dries hard enough to handle in just a few hours, but 3 weeks to a month to fully harden. Once fully hard it is a tough paint. Make sure the surface has something for the paint to hold on to. A nicely machined surface is hard to get a grip. Sand blasted makes for a high grip even finish.

With all of that said. The part can not be to clean.While and after cleaning do NOT toutch it with bare hands, you will leave an oily fingerprint everywhere you touch it. Also be conscious of where you set it down to be sure that that surface is also clean.
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Same experience with rustoleum metallic spray bombs here.

Can be handled in an hour or so, claim hard by 24 hrs. My experience shows it takes roughly a full month to reach maximum cure.

Put anything on it less than a month out and it will "push' it's way through the hardened upper paint layer and into the lower layers which are still "fluid". Makes nice tracks, trails and/or ruts in your freshly painted surfaces. worse case; a big section of your fresh paint rips off with whatever items you've left on your newly painted surface.

It's because of the way it cures. The outer layer tends to cure quickly, which makes you think it's cured all the way through. But what happens is it essentially forms a "shell" that the paint underneath has to off-gas though that "shell". This means it takes a long time for the paint thats not fully cured to get to a full cure because it can't off gas it's solvents as quickly as the very top layers.

It's the same principle that has auto body shops using heated booths to accelerate the cure process....more heat means more engergy in the paint which means it's volatile components off gas more quickly. For most shops, this is a time saver as they can get the car out of the booth sooner (ie: leave it where dust and other contaminants not present in a booth can fall on it) and another into the booth sooner. In a production auto body shop, it's all about the Benjamins....
 
Getting a clean surface before you do any sanding is important. If you sand before getting rid of any oil or other contaminates you let the oil get deeper into the sanding scratches. If the surfaces have been contaminated with any form of silicones they are really difficult to get rid of. Be really cautious about using any form of "fisheye preventer" in your paint. It will contaminate everything it touches and be extremely difficult to remove. Repeated scrubbing with acetone followed by trisodium phosphate scrubbing will eventually get most surfaces clean. Do a couple of clear water rinses. Joints & holes will often bleed contaminates back onto the surrounding surfaces. Only solution is to flush as well as you can with lots of solvent. If you get some flash rust, just fine sand and blow it off.
You can get a good finish brushing with slower flashing paints, not lacquers. Buy a really good brush and use it for tipping.
If you have spray equipment make sure it is clean before hand. Use a nozzle appropriate for the viscosity of your paint. I like HVLP spray guns. Less overspray to deal with. A spray booth will help control overspray so it doesn't get onto you nice fresh paint job. I've got a commercial paint booth, an assortment of spray guns and solvents with different rates of flash off. If you get orange peel reduce pressure, get further away from the surface, use lighter / thinner coats, reduce viscosity.
Keep a wet edge and do about a 50% over lap. Rattle cans can work. Rust Oleum seems to have decent tips.
 
Prep
General cleaning
(grease, oi, adhesive, loose paint)
DA (pneumatic Dynabrade orbital 65grit which will quickly become 80 100 etc use the hard cutting where most useful then extend to surface adhesion

For macroepoxy)
Clean with high pressure air
Clean with alcohol

For powder coat
Caustic prewash
 
My prep depends on what I'm working with. Oil (alkyd) enamels are very tolerant of oil contamination. Even poorly cleaned surfaces can be painted with oil enamel, the solvents in the paint just floats the oil and dirt to the top, adhesion is still good.

I use adhesion promoter religiously since discovering the stuff. Try it and see. The acrylic-based promoter also helps add flexibility and significant chip resistance.

I use enamel dryer (isocyanate based, "for farm equipment" etc.) to help cure times. I put a thick coat of paint on my lathe last Thursday night. It was dry enough to handle on Friday, but I've had space heaters running in the shop 24-7 for the last 6 days to keep temps above 60F, and will continue to do so for another week. Thick enamel jobs do take a good month to reach peak strength.

I use VM&P naptha at 2.5-5% to aid flow and level out the brush strokes. Fish eye is a non-issue when brushing alkyd enamel. Alkyd that is pre-reduced for spraying tends to want to fish eye because the reducer doesn't cut residual oil like the primary solvents do. I don't like paying for reducer, so I thin my own if it needs it or if I want to spray. Machines like strong, thick paint, so machines get paint brushed on.
 
rficalora said:
After cleaning several parts, I wiped them off and then let them dry for a day or two. I then sanded any old paint to smooth the surfaces with 80 grit and followed with an acetone wipe down before painting. I let the paint cure for several days. I decided to test the paint adhesion by scraping a couple of areas with a screwdriver and am finding I'm not getting good adhesion.

I'm using a good quality DTM (direct to metal) oil based paint that's worked well for me in the past so I have to believe there's still too much oil/grease in the metal. In similar situations I would normally heat the part with a propane torch to raise the oils and re-wipe with acetone. I'm hesitant to do that on the lathe parts for fear of distorting parts that have shafts running through them.

What is your process to get good paint adhesion when restoring older, greasy/grimy machinery?
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so if you are hitting it with acetone and there is any soft material (paint, filler) then you are creating a problem. Acetone will soften and not dry off that material as fast as just metal. I wipe with mineral spirits to avoid this issue. All it will due is thin an oil based paint.
If it's bare metal ignore what I said, it should be fine. If your climate is highly humid, acetone can flash quickly and super cool and cause moisture. So make sure it's dry and wipe it with a rag before.

I forgot to mention, I have used TSP to clean, I have also put my lathe parts in boiling TSP to remove the old pain and get rid of the oil and give a good tooth. It worked well.

I always prime. I use Rustoleum rusty metal primer. Even though I am clean and bare, it's a really good primer, and I let it dry. I sand it lightly. I may do 2 or 3 coats of primer, depending. After letting it CURE (not dry) for a period of time I will take a rag with a slight amount of mineral spirits and wipe it clean to get rid of the sanding dust that my vacuuming and air hose didn't dislodge.
Then I paint.

Then I let it cure. I don't mess with it until it won't imprint my fingers. After that, I move it to a safe location and let it sit a few days longer.
Most paint doesn't get really hard for weeks. You can add a hardner..

As far as the all in one primer/paint... :empty:
 
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