Saw your PM. I looked at Rustoleums site and they have two formulas for this particular product. Bright finish cold galvanize has 85% zinc AND 2% aluminum. The one i linked above should have been a picture of the regular cold galvanizing spray which contains 93% zinc by volume. Also states that it can be used on aluminum in marine environments. Aluminized tubing only gets you so far and becomes damaged during crimp bending and welding. This stuff works to cover up those breaches and works very well. Has served me well for years.
I guess one of my concerns is that it will look unnatural. Does the exhaust look good painted? Kinda like it was meant to be that way? Stainless woulda eaten too much into my budget on other stuff - I wish. I already paid more than I wanted to take it to the best place in town (peace of mind - glad I did) I haven't ruled anything out. I'll call the manufacturer tomorrow (I'm swamped today) and see what they say about the heats
Of course they will refer you to the 200 degree heat limit rating for the product. Everything's on their website including the MSDS sheet. With 93% zinc by volume.. even if the 7% burns off?.. you still have a good protective layer left to do the job. As for the high heat paints?.. unless you buy one that has a very high percent of aluminum frit in the formula?.. it flakes off and actually hold water under the coating which is the exact opposite of what you want to happen. The higher price stuff isn't something you want to waste on an exhaust. The zinc stuff i rec'd flat out works regardless of what a muffler shop or paint mfgr tells you. Very cost effective too.
I don't think is true, I certainly have not seen high temp paints flaking off anything. I have it on calipers that I race with, and the discs turn cherry red, high temp fluid reaches incredible temps and no paint flaking occurs. Exhausts that I build and paint don't have paint that flakes off. BBQ's painted with high temp paint haven't flaked off. I can see metals that aren't clean, or something like that, flaking paint off, but I really don't think high temp paint has displayed any of these properties in my experience. Also, the trapping moisture part I don't believe to be true, as it would pretty obvious if the parts rusted out quickly, but again, I have not seen this to be true.
Until you get into VERY expensive resin formulations.. Hi temp paints are always going to be a compromise coating. Cheaper coating are permeable and "float" on the surface due to severe expansion contraction characteristics. This makes them a poor choice for long term rust prevention. Which is of course why they crack,chip,and peel quite easily off 99% of the steel headers sold in the market. And for that very reason.. you'll never find any OEM using them.. the parts would rarely make the full warranty period. Now that's not to say it can't last much longer on aluminized tubing as a secondary "sealer" of sorts.. but the lack of resin content severely reduces long term adhesion. Causes it to be scratched and flaked off with a fingernail after many many heat cycles have occurred and the coating has delaminate from the base material. Anyone who drives their hotrod in wet salty environments will tell you that there is rust hiding under them there loose paint flakes. Maintenance is key with cheap coatings. As a carrer painter for most of my life.. I've probably forgotten more than many will ever know. Not trying to be arrogant here.. just giving a wider perspective is all.
Interesting, the dupont webpage specifically uses the term "resins", although I never noticed it until you mentioned this and made me look it up. They say: "This durable, protective coating is resistant to chipping, brake dust, and automotive chemicals. Formulated with ceramic resins, this high-gloss coating resists temperatures up to 500°F." I had no idea there were resins involved in paint, I just know this stuff doesn't come off of headers, blocks, exhaust pipes, etc. I do realize if you are in an area where they salt the roads a lot, everything rusts. I grew up in Toronto and new cars would have rust streaks running down the paint job in 3 years. Out here on the west coast, in British Columbia, we really don't get snow (maybe a week or two a year sometimes,) so I guess that might explain my success with painting parts and it lasting, but it does work very well for me. I've got exhaust I've daily driven for many years (8 or 9?) without any chipping of the paint, although it does lose it's shine and looks like a more dull finish after a few heat cycles. I use the silver and it ends up looking like dull raw aluminum after the shine heat cycles off.
