Good evening, Aut/o/bots,
Let's talk about paint. I want to tell you about my adventures this week doing a lousy air cleaner housing and valve covers for my 1974 F250.
I used two different paints, because why not? On the air cleaner I picked up Dupli Color engine enamel primer and low-gloss black, which turns out to be a GM-Chrysler low-gloss black. They did not have a flat black. I wanted as flat as I could get because flatter black is a better heat emitter and absorber. Black beats out everything.
Well, took a dremel and removed all of the rivets and cleaned up my nicks and scratches. Then I took it to the steel bead blaster at work - you can fit a truck bed in this. 20 minutes, 10 on each side, with super fine S80 steel shot and they were done, no rust, slight texturing to the metal. I did the plastic deflector by hand using G40 corundum (ground up sapphire) to give it texture, not to remove the epoxy paint. Nothing came sparking clean, which is fine.
I took the parts and put them into a programmable batch oven and set it to 110°C (225°F for one hour. Upon removal, I blasted them with air and then rinsed them with MEK, but brake cleaner would work too - I did only air on the plastic.
They then were dried with air as the solvents flash off and then I hit them with a coat of primer, just enough to no longer see the substrate.
>going through all that trouble just to end up shooting it with a rattle can
I let the dry for 18 hours before I then put them back into the oven for a 30 minute ramp up to 110°C for two hours. Then a 30 minute ramp up to 130°C for two more hours, and then a final 30 minute ramp up to 150°C for a final two hours. I did not notice any extra outgasing. This is to simulate the requirement of a full week of cure.
I then repeated the above twice doing thin coats of black. I did not do the advertised "medium" coat of paint, because what the fuck constitutes "medium" out of a spray can?
Perfect. But I don't have any photos to upload because I am a giant faggot.
Next, on to the valve covers.
don't get steaming hot brake fluid on it or it'll eat the paint within like 3 minutes.
>source: image related. duplicolor engine enamel.
So, back to the valve covers. Next, I wanted to try out this Rustoleum "High Heat" stuff, advertised to withstand 1200°F, or 648°C. I have an oven that can reach 800°C, so why not?
I did the same prep procedure, used about 3 cans of brake cleaner and a bottle of purple power and MEK to get the gunk out of the guards. One of the valve covers did not come spotless after 20 minutes in the blaster. This was my mistake.
So, yes, Rustoleum High Heat will stand 640°C, however, the area of 50-year-old enamel bubbled and cracked, so now I'm going to go and redo that valve cover, because I can and I want to. The Rustoleum degasses a great deal, which didn't bother me due to the fume hood on the oven I was using. The Rustoleum tech bulletins suggest that it does not begin to cure until 170°C (338°F).
They actually recommend 20 minute ramp to a Temperature "A", a 20 minute soak, and a 30 minute ambient temperature cool-down, repeated three times, at 200, 400, and 600°F (94, 205, and 316°C). The final temperature is unnecessary for parts that will not see that heat.
After the cool-down from a 2 hour soak at 400°F, I noticed the paint that had remained was just flaking off. I will do this again.
Everyone else, tell us your stories and secrets!
Different paints require different temperatures.
The correct way (The German Way) to powdercoat is to preheat to the required temperature where the powder paint melts and then increase to the polymerization temperature. Your heating profile would not work for my powder paint, anyway. I know that much, as a fact.
The stuff we have is completely resistant to everything except brake fluid. It takes roughly 24 hours to soften our powder paint and it does not scratch without significant pressure (I have to lean on the cutting blades, and I'm a big guy).
never use a rattlecan for anything
use automatic parts washer
before painting clean the part with bug and tar remover or soap and water and bake it off in the oven before painting
>never use a rattlecan for anything
This shit would like to have a word with you