With fabricating the new spinny-thing install on my heap recently, I used the Cerakote products to coat the hot-stuff inside and out. Cerakote provides fairly well detailed instruction for applying the product on their website.
Using said instruction (and supplementing here and there) . . . .
- I put all the parts in the dishwasher with a very strong dose of the dishwasher detergent (most are based on Sodium Hydroxide, AKA: Lye) followed by multiple hot water rinses while still in the machine. This helps ensure any oily residues are removed.
- Without touching the metal goods with my oily booger-hooks, I then placed them in the oven, at 500*f, for an hour (after they've come up to 500*f). This further ensures any oily residues are burned.
- Again, without touching the goods with my booger-hooks, after allowing ample time to cool, I bagged the individual parts in individual, new zip-lock plastic bags. NOTE: Any straight cast Iron parts will have begun to oxide at this point, that's OK cause you're gonna get that next).
- Now, it's time to blast the goods with the likes of 120grit Aluminum Oxide (RTFM). DO NOT Glass-Bead blast the goods as Glass-Bead media simply dimples the material surface. You want to leave the surface with sharp peaks and valleys for the Cerakote products to properly mechanically bond to the articles. Do not use too coarse of a blast media as you don't want the peaks and valleys too deep as the Cerakote product may simply fill the valleys, leaving the peaks standing proud, uncoated. Again: RTFM! REPLACE/RENEW the blast media often as the media fractures/powders with use.
Before removing the goods from the blast-box, make DAMNED sure to blow any and all residual blast media from any nooks and crannys.
The blasting process will most likely turn the surfaces to a dull, flat textured surface. If it still shines in the least bit, continue blasting.
As an example, Before (raw 304 Stainless steel):
And after:
- Again, don't use your booger-hooks to handle the now blasted goods (Use something like the disposable Nitrile gloves). With that, place the goods in the individual plastic bags till it's time to coat them.
- As I coated both the internal and external surfaces, I had to pay attention to the individual coating instruction. I used the Cerakote C-7900 (glacier Titanium) air-cured product for the exterior surfaces. I used the heat-cured Cerakote W-209 Insulkote product for the interior surfaces.
With that, I coated the interior surfaces first with the W-209, followed by the exterior with the C-7900.
READ AND FOLLOW the product application guide. You want a 1~2 mil SINGLE coating IIRC. DO NOT apply too thick as in too heavy a coat. DO NOT apply more than one coat. (If you screw-up the application, you MUST remove it all and start over. PERIOD). I used the Cerakote recommended gun with dry Nitrogen gas as a propellant.
I let the C-7900 product air-cure for a week (as per the FM).
Then placed the goods in the oven at 500*f for two hours to heat-cure the W-209 internal coating:
NOTE: IIRC, Cerakote wants you to heat-cure the W-209 with a notably higher temperature, but I couldn't find a workable excuse for the wife as to why the cabinets around the oven look toasted. Hence, the two hour cure time of 500*f. READ the product instruction and follow as best as is possible in that regard.
- I recommend one consider your overall build schedule and save the coating of goods for the end of the build. You don't want to risk mechanically damaging or fouling the coating(s) during subsequent disassembly and reassembly.
- Be prepared for anything made of straight cast Iron to begin corroding soon. In the past, I've tried the Jet-Hot applied, Jet-Hot coating, only to have it start showing corrosion in short order. Sent it back under warranty and had it stripped and recoated, only to have it start corroding soon thereafter again. Screw Jet-Hot.
I then had that product stripped off and had the local Cerakote dealer apply their product. It started showing light corrosion a little over a year later.
My application of the stuff this go round is already showing corrosion on the straight cast-Iron secondary exhaust housing. :doh: The 304 Stainless components as well a the high Nickle cast-Iron primary exhaust housings are still pristine.
Your mileage may vary.
Hope this helps.