Automotive Spray Paint
The following comes from a recent topic on SmokStak, which can be found on the Internet at: www.engineads.com/ smokstak.cgi. As ever, various individuals started, commented on and concluded the following bulletin board thread.
Can anyone tell me if automotive spray paint like Centauri has any advantages over canned spray paint? Also, what is the best brand of spray can paint to use for resistance to gas and heat? I'm not set up for a spray gun, so I'll likely be using a spray can for my Witte. -Chris
When I painted my Mogul I did not trust spray cans to be the correct color. I got the DuPont number and had spray cans mixed for me. It was expensive ($10 per can), but I feel it was worth it and the color is perfect. It will get soft with gasoline, so I need to coat it with clear. It went on great and looks great. - Al
I can tell you for certain that the cheap 98-cent Kelly Green from Wal-Mart will shift towards blue when exposed to 300-plus degrees F on steam lines. I use it anyway and just touch up the problem areas yearly. I've also had implement enamel from the local Farm & Fleet (IHC red) that actually peeled off in strips. If you spray bomb, Rustoleum is pretty good, except that you have to watch the second coat, it can and will react with the previous coat to give you a 'crinkle' finish. - Allen
There's a trick to spraying Rustoleum - read the fine print on the can. You cannot spray a new coat after one hour or before 48 hours. In other words, you have to get all of your coats sprayed within one hour or wait two full days before spraying another coat. If you do otherwise, you'll get the dreaded crinkles and then you will have to start all over again. - Harry
I noticed with Rustoleum that after maybe 10 years it peels off - leaving the primer intact and in great shape for the next paint job. You can brush paint Centauri, but don't do it if it's over 60 degrees F because it dries too fast. I know they tell you to paint when it's over 70 degrees, but I had good results painting my 8 HP Mogul with it when it was 40 degrees in the barn. The cold actually slowed down the drying so I could finish the job before the brush set up. You need to wear a good mask when you use the stuff; it's got some pretty unhealthy chemicals in it.
Probably the most important part of the paint job is the prep work. Everything must be clean and oil free. Spend as much time on it as you need to get it right and it will show in your finished work, no matter what you paint with. I have had good results with Demkote paint sold by Grainger's. Also, Krylon seems to be pretty good. Rustoleum, by far, takes the longest to dry. Good luck -Rob
If you want to use Centauri in hot weather (which we have a lot of down here in southern Mississippi), use a high temperature thinner. It lets the paint dry much more slowly and lets the brush marks flow out before it dries. If it still dries too quickly, you can add a retarder to it and slow it down even more. By brushing it on, you can add the gloss hardener to it and make it gas and oil proof. But if you're going to stay in this hobby, get a paint gun and start practicing with it. I think you'll be much more satisfied with the results. You will also have access to an endless number of colors from DuPont, Sherwin Williams, Ditzler, etc. - David
What we found out (and were also told by our automotive paint suppliers) was that two-and three-part mix automotive paint is harder on the surface and is much more resistive to UV (sunlight). When we spray red on our field trucks (by can), it will start fading in about four to six months. Automotive paint will stay shiny for a very long time. It might make a difference for you if you are leaving it out for long periods of time. - Darryl
Lowe's building supply house has a spray outfit that includes a quart cup, 1/2 pint gun, air brush, hose and fittings for about $60. It's decent equipment, but the key is to keep it clean. - Chuck
I'm still going with automotive acrylics and hardener, but it sure is getting expensive. - Larry
Centauri is great, but will lift if soaked with gasoline for any length of time. Most any paint will do so except the three-part urethanes. They are the best, but expensive and hazardous to use. They are very forgiving when sprayed, build-up multiple coats quickly and have a super gloss. NAPA sells Duplicolor acrylic enamel in spray cans. The color selection isn't great, but it is as good as Centauri and sells for about $4 a can.
I weather tested it on my mailbox, and it still looks great after a year. Rustoleum faded in less than two months in the weather. And Rustoleum doesn't dry fast enough to remain dust and bug free. I used to get Centauri put in spray cans for $3.65 a can plus the cost of the Centauri paint. You get about six cans to the quart, plus a little left over. This is somewhat expensive, but a good way to handle small projects.
For larger engines, bite the bullet and get an inexpensive HVLP (high volume, low pressure) spray gun. Even the cheap ones are great. I got the pressure cup-type and find it more convenient for use around my messy shop. I have also found a spray, gloss shellac coating to help in gasoline spill areas. It is not soluble in petroleum solvents. Just don't spill any alcohol on it. -Jeff
I have to agree with Jeff. I used PPG's version of Centauri and the paint did peel when soaked with gasoline. I used it on an Allis-Chalmers, and other than the area just below the fuel sediment bowl I have been happy. The tractor still looks good other than that area and has otherwise held up well. - Dave
Did you add the gloss hardener to it? If not, gasoline will soften it up. With a hardener it cures out very fast, and then has properties much like urethane without the mess. After it sets overnight it is pretty much bullet proof, even on sheet metal fuel tanks. I have seen it wrinkle around gas tank necks, but that is usually caused from the flux used in sweating on the neck and cap. Generally speaking, gas does not bother it - if it did, it wouldn't be worth much on a car, because every time you filled your tank you would wash the paint off the quarter panel - David
A few years ago, after a gasoline wrinkle showed up under the weeping check valve on my Hercules, I called Dupont and asked them about gasoline proof paint. They told me that they only had one type of paint that would be considered gasoline proof, and that was 'Imron.' Imron, of course, is a three-part urethane. I asked about Centauri and hardeners, but they said it would still wrinkle if the gasoline was left to soak on the paint. PPG said just about the same thing.
The key is 'soak.' A spill or two (or three) won't bother most cured, quality paints. But an overnight soak will discolor the paint and eventually lift it. Just watch those leaks. Most good auto finishing supply houses will pack aerosol cans for you, but some cans and spray tips are better than others. You want the flat, fan spray tip, which is usually a blue colored tip. I have mixed Imron and used it in a universal aerosol spray kit found in most hardware stores. It worked very well as long as the job was small. The propellant can starts to freeze up if you spray too long. -Jeff
I have heard that when Imron hardens, it really hardens and won't come off easily if you need to strip the item for some reason in the future. I saw a tow truck at a body shop that was painted with Imron a good number of years before, and when they sandblasted it, there was still quite a bit of paint left on the truck. - Bill
Any idea where store I can buy custom spray cans? Do they use compressed air as the propellant or propane? I have spray guns and the stuff to do gun painting, but those cans are so convenient for little jobs. It would take me a week to cover everything in the barn, plus disposing of the waste thinners. I think it would be nice to match homemade spray bombs and good paint in the right color. - Rob
I get mine put into spray cans at my local automotive paint store. It's not cheap, usually $17 to $20 a can. They will make any color in any brand they carry, and sometimes when I buy a quart I have them put some of it in a spray can. That way I have a perfect match for later use and it won't be dried up two years later when I need it. - Allen
SmokStak is an engine conversation bulletin board with over 50,000 messages on file and is part of the Old Engine series of Web sites that started in 1995 as 'Harry's Old Engine.' Harry Matthews is a retired electronic engineer and gas engine collector from Oswego, N.Y., now residing in Sarasota, Fla.
'What we found out (and were also told by our automotive paint suppliers) was that two- and three-part mix automotive paint is harder on the surface and is much more resistive to UV (sunlight).'