DIY piston Cerakoting
 

I'm current throwing my first rebuild together and I've been looking at Cerakoting the stock pistons as a cheap improvement to the engine. The stuff is reasonably inexpensive, air cures and can be sprayed out of a HF gun - Cerakote C-110

Here's their DIY video. I'm a little thrown off by the fact that they spray it into the ringlands as well, and based on their gallery it looks like a lot of shops mask the ringlands. Apparently it's also usable on bearings :confused:. Just curious if anyone here has firsthand experience with the stuff.

Data sheet is attached. Coating thickness is ~0.1 – 0.5 mil (0.0001"-0.0005")


https://cimg0.ibsrv.net/gimg/www.mia...3418333697.png
https://cimg2.ibsrv.net/gimg/www.mia...f922c4953a.png

So apparently these bearings were coated and run for 16 races in a Esslinger Midget Engine. Looks REALLY damn clean.
https://cimg0.ibsrv.net/gimg/www.mia...dc06581a53.png

bump, I do my own powder coating and have been eyeing Piston and their side skirt coating.
Ive also seen it sprayed on the tops of the combustion chambers and valve faces

Well I'm gonna pick up a cheap toaster oven for cleaning parts and I ordered some C-110 (microslick) and C-186 (piston thermal coating). Gonna make a DIY blasting cabinet and try this shit out. Planning on doing micro slick on pistons and valve stems at least. If I bought more I would do the whole crank to help it shed oil. Also going to coat the piston tops and valve faces with the thermal coating.

Annoyingly Cerakote has several pictures of coated bearings on their site using C-110, but their tech guy said that it will almost instantly shear off when I asked him about surface prep. I've seen some success stories on forums showing the coating still intact after disassembly, but I'm a bit more hesitant to try it on the bearings now.

Following - interested to see how this works for you.

Some people claim these products are snake oil, but obviously other thermal barrier coatings work well on piston domes and combustion chambers.

The gun guys swear it's the best stuff since sliced bread so I wanna give it a try. If I have any extra mircroslick I'm gonna coat my car keys too. A dry lubricant that won't rub off on clothes sounds like a great option to prevent lock wear. The coatings are also gas proof, so I might try them on a motorcycle carb in the future as well.

I'm gonna try the 'put it on everything and see what works best' route haha

update!
The piston top coat is actually quite easy to apply as this is my first time with a HVLP gun. It's a bit thin, but has good coverage and didn't seem to want to run too much (also helps that you're coating a horizontal surface). I did have to redo the coating on 3 of the pistons though because I was not thorough enough on the surface prep, it has to be perfect.

Top coating:
https://cimg6.ibsrv.net/gimg/www.mia...5f39be86e9.png

Now the Micro slick is another story.... It's just as thin as straight acetone, their application video says 3 thin coats but their documentation says one thin coat. My first coat looked like it was water with gray streaks in it. I got coverage on the second +3rd coat but it ran like crazy. I'm going to have to blast these again and give it another shot. I'm thinking that the low temperatures were a big factor and I also had pressure a little low compared to their spec. I have just enough for 1-2 more attempts so fingers crossed. Oddly, even though the piston coat goes on thicker I used less than a 5th of the bottle. I'm thinking that I maybe under mixed it and that my coats were also much thicker than I thought

https://cimg1.ibsrv.net/gimg/www.mia...0e92de7308.png

Redid the skirts and I am very happy with the results.
https://cimg1.ibsrv.net/gimg/www.mia...8044085e43.png
https://cimg4.ibsrv.net/gimg/www.mia...22e5276bfa.png

So what changed on the 2nd go round with the skirt coating? What’d you do differently?

asking for science!

They look great!

Thanks!
Haha I'm usually more detailed but it was late and I was excited to get some sleep, but also excited for successful coatings :party:.

A lot of it was following procedure religiously and focusing on gun technique. I had the pressure a bit lower than they spec'd. Here is my full process:


Prepping

• Media blast pistons at 40psi or so with 100 grit aluminum oxide
• Clean with compressed air
• Wear gloves and scrub down with acetone, skin oils will mess up the coating so do not touch anything without gloves after it's blasted
• Repeat air and acetone until you are 1000% sure there is nothing on the piston

Piston Thermal coating

• Tape off skirts
• Shake Cerakote for 5 minutes minimum
• Pour through 150 micron strainer into HVLP gun
• Set gun for 20-30 PSI and a 3-4" or so oval
• Do 2 wet (not heavy) coats on piston tops. Wait a few minutes in between the coats so you don't get runs.
• As long as your pistons were totally clean this is easy and simple.
• Let cure for 24 hrs min before step 2
  

Micro slick coating

• Bring Cerakote, pistons and gun inside to warm up to 70° ish
• Struggle to get shed to 60° with heater
• Tape off, acetone wipe and blow off pistons. Rubber plugs also help a lot to make this easier
• Shake Cerakote for 5 minutes minimum
• Pour through 50 micron strainer (they spec 44 micron, but I used what I could find that wasn't crazy expensive)
  
  For the underside of the piston (c-110 stops oil from sticking to parts as much)
• Play with air pressure and fan/liquid so you can get a nice small dot instead of a fan that just barely wets in the center from 6" away or so,18-20 psi worked for me
• Use short bursts and coat the underside of the piston and try and get in all the little nooks
• Let sit 10 min so it sets up and won't run. Time will vary depending on your temperature. Make sure to shake the gun before applying second coat as the Cerakote can settle after 5 min or so
• I gave the underside one more light dusting to get any spots I missed. I figure two coats is enough since it's not on a wear surface and I had good coverage.
  
  Piston skirts
• Set regulator on gun to 30 PSI when flowing air (Cerakote spec)
• Dial fan down to 3" ish wide
• Turn down fluid until it's just getting wet in center when gun is 6-7" from surface
• Play back and forth with fan and fluid until it's set since it feels like there's a little crosstalk
• Do one light coat with minimal overlap, make sure you have good light etc and the part is elevated so you can get a good square shot at it. Coat needs to be light but must still be wet
• I waited ~ 10 minutes before adding another thin coat since it was so cold it took a while for it to set enough to not run. Make sure to shake the gun before a coat
• Wait another 10 or so and do a 3rd light coat.
• You're done!
• You should be tack free in ~ an hour, but I let it sit as long as possible. Partial cure at 24 hrs and full cure after 5 days

Main things I learned -

1. Make sure that you're staying the same distance from the part while you're spraying, too close and you'll run, too far and the coating will dry before it hits the part. It's easy to drift if you're really focusing on the spray pattern on the part.
2. Shake everything extremely thoroughly.
3. Painting in the cold sucks.
4. When I went into my paint 'booth' I sprayed everything off and then stayed in there and let things settle for a few minutes before proceeding. Opening and closing doors will blow dust around. I cannot stress enough making sure there is NOTHING on the surfaces you're coating.

This is the HF gun I used, nozzle meets the spec from Cerakote. I'd recommend thinning some paint out a lot with acetone to practice with spraying something really thin, then doing piston coat and then the skirts as that is order of difficulty.

You have to be careful, but this is totally doable as long as you are methodical and willing to practice/redo things if you mess up. The other coatings look like they're closer to the piston coat, and that was so easy to spray and came out looking so nice that I'm actually ordering more Cerakote to paint things with. It's supposed to be more durable/corrosion resistant than powder coat, but you can apply it at home and it's quite affordable.

I know that's a wall of text, but let me know if you have any questions!

AWESOME, great work and documentation, keep us updated thanks! ill be for sure ordering some too.
I didnt know it gets sprayed into the ring lands too

Thanks!

Full disclaimer, many people mask off the ring lands prior to spraying microslick, and other coating mfrs seem to mask them too. Cerakote's instructional video showed them spraying into the ring lands (supertechs are also fully coated with whatever they use) and the fact that the coating is so thin should mean that the rings should still move freely. Actually if all goes well the rings will be able to move better than if it were uncoated, so I decided to fully guineapig myself. Once I'm certain that this has cured enough I will test fit rings.

my only worry would be the rings wearing the coating out quicker and maybe gunking up the ring gaps but like you said others seem to have done so, and you should be able to tell if its working and staying put in pretty short order once its running.
are you doing/getting any kind of treatment to the rings themselves?
and have you considered spraying the valves and combustion cambers in the head with the thermal coat too?
id not seen the the undersides of pistons coated, has me wondering if you could coat the inside of the head and block to improve oil flow back to the pan

AFAIK it's designed to be somewhat 'wear to fit' so in theory unless it flakes in a particularly crappy way it shouldn't jam things up, but I honestly have no clue until I get this running.

If I were doing things all the way I would have microslick on the crank (not the journals), rods, and valve stems as well as cams to fling oil off and free up a bit of HP. I'd then have the thermal coating on the valve faces, combustion chambers, exhaust manifold, supercharger and the coldside intake piping. Cerakote also says that they coat the inside of headers by pouring the stuff in and sloshing it around, so I'd be curious about coating the exhaust ports in the head too.

That being said the prep time and painting was a pain in the ass with my facilities and is holding things up and I'm gonna start missing events soon. I'm weighing doing the rods and valves currently, but I'm a bit skeptical to go all in when I haven't tested the coatings myself yet. If the stuff I do holds up well on this engine I will go all out on the next build and coat everything that I think is applicable.

edit: I'm just using OE rings in OE pistons, nothing fancy here

Great write up and details. Do you have any update on this? Very interested to see any results. I just thought about this today using stock pistons on a future rebuild. My application however would be full time e85 and I need to look into if these coatings play well with the ethanol. Would love to hear if you got things up and running and your opinions on the coatings.

Thanks for the detailed write up. In hindsight, do you think you would have more control of the quality of the spray pattern with an air brush?