I'm going to answer this one quickly here and then open another permanent post that will explain how to use the High Temp coatings later today. (I'm also going to add another permanent post for POR-15 Fuel Tank Sealers since so many people use them too).
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Two of our High-Temp coatings are recommended for use on headers. POR-20 (rated to 1400° F) and Black Velvet (rated to 1200° F).
Prep is a little different than our other coatings.
Surfaces to be coated must be clean, dry, and free from oil, grease, and any other coating which cannot resist high temperatures (paints, varnishes, lacquers, metal prep coatings, etc). Sandblasted surfaces are ideal (recommended for headers), as are wire-brushed or sanded or filed surfaces.
After sand blasting you may wipe with a clean damp cloth to remove any dust, but don't apply any solvents. Many people are accustomed to wiping metal with lacquer thinner before painting, but this will cause problems. Also, sandblasting is better than using glass beads because it will etch the metal a bit more.
You also want to apply these coating with full coats but not so full that it runs (rather than the thin coats we recommend for the rust preventive POR-15 coatings.) Brush it on and any streaks will melt away once you fire the headers up.
Just be careful that after you sandblast that you don't spread any fingerprints around on the metal.
You can find some technical info on our site here:
http://porshop.com/higtemcoat.html
http://porshop.com/porshophigte.html
