Baked on Enamal Spray Paint

RandyM

Mr. Deliberate
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I just had an interesting experiment on a bracket I was making. Last weekend I painted it and left it to dry all week. Well, I went to mounting it and found that it was still very soft and sticky. The paint was enamal from a spray can (fresh can). After not wanting to wait any longer on "if" it would dry, I fired up the powder coating oven and baked it. Not ever trying this before I was unsure as to my results. I mean what temp and time do I use? I figured it didn't really matter as I was probably going to have to re-coat it anyway. So, after slowly turning the heat up to 200 degrees and baking it for about 3 hours I let it cool and removed it from the oven. The reason I baked it so long is that the paint stayed soft as long as it was hot, which I was not expecting. I then figured that it might harden up once it cooled down. Yup, that is exactly what happened. So, long story short, everything turned out perfectly and I was able to finish the project. Has anyone else experimented with baking paint? Please let me know how it turned out for you. I may do more of this in the future just to speed things up.
 
I just had an interesting experiment on a bracket I was making. Last weekend I painted it and left it to dry all week. Well, I went to mounting it and found that it was still very soft and sticky. The paint was enamal from a spray can (fresh can). After not wanting to wait any longer on "if" it would dry, I fired up the powder coating oven and baked it. Not ever trying this before I was unsure as to my results. I mean what temp and time do I use? I figured it didn't really matter as I was probably going to have to re-coat it anyway. So, after slowly turning the heat up to 200 degrees and baking it for about 3 hours I let it cool and removed it from the oven. The reason I baked it so long is that the paint stayed soft as long as it was hot, which I was not expecting. I then figured that it might harden up once it cooled down. Yup, that is exactly what happened. So, long story short, everything turned out perfectly and I was able to finish the project. Has anyone else experimented with baking paint? Please let me know how it turned out for you. I may do more of this in the future just to speed things up.
My work bakes all of their painted parts at 140* for an hour or two depending on what the part is. We use epoxy, eurothane and water based paints. Tim
 
Some body shops use curing heat lamps after a paint job and has been done for years. A old auto paint guy told me a long time ago to use cold water on a Enamal job after a day or two to harden the paint, but no hard stream or rough wiping. A uncle of mine back in the 60's worked as a painter in a shop that painted metal office stuff and baked it afterwards. I wonder if this would work on rustolium oil base paint? I will have to try this, thanks for reminding me of this.
Paul
 
Some body shops use curing heat lamps after a paint job and has been done for years. A old auto paint guy told me a long time ago to use cold water on a Enamal job after a day or two to harden the paint, but no hard stream or rough wiping. A uncle of mine back in the 60's worked as a painter in a shop that painted metal office stuff and baked it afterwards. I wonder if this would work on rustolium oil base paint? I will have to try this, thanks for reminding me of this.
Paul

So Paul, did you try the cold water trick? I am having a hard time understanding how it would actually work. Yeah, try it on Rust-Oleum and report back. My guess is, it will work pretty well. I had a hard time finding anything technical on the web. Looks like a lot of experimenters on other forums, but nothing from any of the manufactures on baking.
 
I have had very good luck baking solvent based paint especially enamels which can take a long time to harden up. It is particularly useful on wrinkle enamel which, once you figure out how to make it wrinkle, still takes forever to get hard enough to handle. Enamels "dry" in two stages, the first is the evaporation of the solvents and the second is the polymerization of the oils in the paint. Generally, the solvent evaporation does not take too long depending on how much paint was applied, but the polymerization can take weeks or longer to complete. I remember reading that old auto enamels could take months before they were hard enough to wet sand or polish. Anyhow, baking accelerates the polymerization process and really helps to make the finish harder sooner. If the paint is applied too heavily and there are solvents trapped in the paint film, you do run the risk of boiling the solvent embedded in the paint which produces a mess. I generally let the parts get dry to the touch and then put them in a cold oven and turn it on. It's a lab oven with a convection fan and heats pretty slowly and there are not any exposed heating elements, so there is no radiant heating like you might get in an ordinary kitchen oven. Radiant heating is a potential problem since the part can get way hotter from the radiant heat than from the air temperature in the oven. I generally run the oven a 200-250F. I set the timer for 3-4 hours and just let it heat up and cool down on its own. I have also found that getting the paint harder helps a lot with the removal of masking. If the paint is not hard, it tends to come off with the masking tape which is really annoying.
You don't have to have an oven to bake the paint. I've used a cardboard box and an old, low wattage hair dryer on many occasions. You can also heat the parts other ways. I recently rebuilt an old lathe and some of the parts are just too big for my oven so, for example, I heated the pedestal base by arranging a heat gun to blow into it hich warmed the whole thing nicely and the paint was hard enough to proceed with the reassembly in less than a day. Needless to say, any of these alternatives require careful monitoring while in operation at least until you're sure the whole thing isn't going to catch fire or melt something.
Baking works for me. Your milage may vary
 
I add automotive enamel hardener to any oil based paint such as Tremclad or Rustoleum. Dries in an hour or two and gives a harder and shinier finish.

Greg
 
Great information. I am about ready to try my first "REAL" paint job. A 1939 International Farmall "H". Never done more then rattle can before as I hate the mess and always get heavy handed because I am impatient with the whole procedure. My painter delivered his gun, said "About time you learn. Good project for it. Good luck", and left. What an attitude!
 
Epoxies are normally thermal setting, IE they cure with heat. Heat lamps put off UV, so it can degrade the shine, oven temps need to be warm but not baking hot (140ish) not 250....Tim
 
Randy,
I have tried the cold water trick and it seems to work on some test pieces that I did years ago. I will have to try hardener with Rustolium to see how that does. I do agree with the lower heat for the regular paint and I think that powdercoat takes higher heat because you have to melt the powder to get the finish. I have also cranked up the heat a little to warm the metal a bit before painting and seems to stick better. I do need to paint a steel man door before winter and was thinking what to use that will dry quick so I can put it back on the same day and car paint is a little costly. I did use some paint a long time ago from a hardware store but don't remember the name and it dried real quick because it rained as soon as I was done spraying it and no water marks at all on it and it is still on my neighbors trailer since the mid 70's and still looks good.
Paul
 
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