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Old 04-09-2016, 09:28 AM   #1
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Gun Kote sealing of metal for anti corrosion

I bought some Gun Kote to coat piston skirts, then I sealed up some cast iron pieces and now this Sendure bolt on bronze and copper end hose connector cap for the heat exchanger.

It has a hard surface and it is oil-gasoline-acip proof. You spray it on using an air brush or you can paint with an artist brush. Clean up with acetone.
Bakes in the oven at 325*F for 90 minutes. And I baked on 2 coats for this piece. The inside of the copper elbows I touched up with the small brush.

This part of course did not need anything being bronze, but it looks good now. Iron parts do need protection, and they also look good now.
I did not grit blast with 125 grit AlOx this part I did grit blast the piston skirts.
I did clean it first in Muriatic acid. The cast iron parts I coated are already rough surface.

The copper ells on this part were more corroded than the bronze base. I decided to coat this and see how it looks in a year.

Gun Kote is a phenolic resin and good up to 730* temps. This one I used is Nano Gun Kote.
Grit blasting the parts is recommended to key the surface before coating.
This part is from 1970.
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Old 04-20-2016, 11:55 PM   #2
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Interesting stuff. Thanks for the info.
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Old 04-21-2016, 12:41 AM   #3
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Very interesting. Especially many of their other products. Thanks for posting.
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Old 04-21-2016, 12:58 AM   #4
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How do you get your wife to let you bake that in the oven? Are you single?


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Old 04-21-2016, 10:28 AM   #5
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It really has very little odor baking in the oven, if you smell anything, it is a plastic type smell. The odor mostly comes when painting on the Gun Kote, it has a smell much like a auto oil based paint. Baking small parts I bet you hardly smell anything.
It wont hurt your oven. There is no lingering odor at all. The VOC go into the air just like a paint, really this is very similar to paint, put it on like paint. the difference is the chemical reacting due to heat cross linking the phenolic resins after the VOC evaporate.

Make sure to shake the can before spraying-painting. All the precautions regarding paint do the same with Gun Kote. Grit blasting is best, dont bead blast, the rough surface is good for adherence and bead blasting is too smooth.

A grinding wheel, the little grains are all glued together with phenolic resins and brake linings are made with phenolic resins. The resin is modified with pigments and particles to give it whatever properties the manufacturers wish. So this is a very tough gluey type of thing.

I noticed when I sanded Gun Kote, it sands smoothly no gumminess.
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Old 04-21-2016, 10:59 AM   #6
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Here are my coated piston skirts.
I was careful to grit blast and careful to clean before and afterwards these pistons since the rods were still pressed on when I blasted and coated them. I shielded where I did not want to grit blast and spray with duct tape.



I sprayed about 3 -4 coats which built up a thickness of about .002 to .003 on the pistons, bringing my bore clearance to .003. Before gun koting them, the clearance was .006 to .007, which was a little loose. It is spray then bake, then spray then bake, etc... Sometmes I sprayed twice then baked.

After start up and run for hours, there is still no odd noises, no piston slap. SO to save $500 on new pistons, I was thinking other people coat the pistons, why not try it as an experiment? This is also advertised as having lubrication built into the material.



I bought a pint of the Nano Gun Kote in aqua blue. I have used about half the can and done a lot of coatings.
http://www.kgcoatings.com/products/c...eries-gun-kote

This I used to spray, and it is good quality, can focus down the spray to 1/4 inch.
http://www.amazon.com/PointZero-Sing...ilpage_o03_s00

This I used to grit blast, worked great. I reduced psi to 35 since they recommend that on aluminum.
http://www.amazon.com/Campbell-Hausf...ilpage_o02_s00

The ALOx 125 grit I got from Virginia materials, about 35$ for 50 pound bag.
The grit goes everywhere, so if you spray on a tarp, you can recover it and use it again.
I dont have a blast cabinet.
http://www.yellowpages.com/norfolk-v...89?lid=1195489
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Old 04-22-2016, 08:21 AM   #7
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I still can't believe that your wife let's you do that in "her" oven. Are you allowed to degrease engine parts in the sink too?
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Old 04-22-2016, 09:19 AM   #8
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I still can't believe that your wife let's you do that in "her" oven. Are you allowed to degrease engine parts in the sink too?
I cooked them while she was at work.
If I use the sink for that, she finds out and is not happy.
Regarding the oven, if no obvious traces, then not much to complain about.
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Old 04-22-2016, 09:38 PM   #9
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I got a stomach ache just looking at those pistons. It means the engine is disassembled? Ouch!
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Old 04-24-2016, 08:20 AM   #10
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I got a stomach ache just looking at those pistons. It means the engine is disassembled? Ouch!
Engine had a few issues, so I took it apart to see what was up with it.
Was blowing blueish smoke at revs above 2000 under load. And had some small blowby. The cylinders were polished like glass and the valve seals were crap. So when I honed the cylinders, that made the piston to wall clearance looser than I like, was .006 to .007. Coating Gun Kote brought it to .003.

It is all together and seems to work good, zero blow by, no piston slapping, good power. But without tearing down again, who knows what the coating looks like in a few years.

If it never gets piston slapping, and never gets blowby, then assume the coating is ok.
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Old 04-24-2016, 08:51 AM   #11
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Greetings,
Mr. 717. I'm NOT a mechanic by any shape or form but could you have knurled the piston skirts to have achieved the same, possibly longer lasting, effect regarding clearances? Phenolics are quite durable but I would question their use in such an extreme environment.

Interesting stuff that Gun Kote. I'm going to look into it for my own use. Just have to figure out what I'll use it on...And no, I'll not use my oven for baking. BBQ grill possibly.
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Old 04-24-2016, 09:42 AM   #12
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Greetings,
Mr. 717. I'm NOT a mechanic by any shape or form but could you have knurled the piston skirts to have achieved the same, possibly longer lasting, effect regarding clearances? Phenolics are quite durable but I would question their use in such an extreme environment.

Interesting stuff that Gun Kote. I'm going to look into it for my own use. Just have to figure out what I'll use it on...And no, I'll not use my oven for baking. BBQ grill possibly.
Knurling while it does work, it is a short term fix. The surface area of raised knurls is low to the loads of piston against cylinder. So if plain smooth pistons wear down, knurled pistons wear down faster.

If you have a small toaster oven that will work for Gun Kote curing. When I talked tech support, I was told higher heat will still cure Gun Kote but may discolor the pigment.
You can color coat anything that you can heat in an oven to 325 *F. Gas grill should work too. There are many videos of people Gun Koting things on youtube.

I have some old chrome large handles to grab on with hands that pitted. I was thinking use some JB weld to smooth the pits, then spray Gun Kote on them. They will be blue colored.
Gun Kote you can overspray any color with another one. Maybe white would stand out less, although blue people will notice them. Anything you coat should be grit blasted, to make more certain the coating is long term durability. I will grit blast these chrome handles, I think this will get rid of the smooth shine to let the coating stick well.
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Old 04-25-2016, 08:51 PM   #13
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I decided to coat some carb parts as an experiment doing things a little differently.
For the coating of these parts all I did was clean in muriatic acid, scrub with soap and water using SS scouring pads and toothbrushes.
Then no blasting, and just painted with a small artist brush. I coated and baked twice.

Without using the airbrush, the coating is more uneven, but the finish seems just as hard to me.

I lowered the temp to 315 since the float is a soldered part. The float survived intact.
Bowl is steel, and a few years ago, I had torch brazed some bronze on the steel as it was rusting in E10 gasoline. Doing that was a pain, and I don't recommend it. Silver brazing would have been easier.
The braze coating helped the steel from rusting, however it would still turn a brownish green in the fuel.

So this coating which is supposed to be fuel proof will keep E10 from causing any corrosion. And the brass float from maybe eventually getting pinhole corrosion.

Threaded needle valve and the float pin still fit as before.
My guess is it will still be fine, but not as durable as if it was blasted first.



The metal handle for a faucet was rusting. I just cleaned in acid and coated as another outdoor test.

I am also thinking that Gun Kote could repair a bad float with pinholes.
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Old 04-25-2016, 09:37 PM   #14
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Any concern about added weight of float?
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Old 04-26-2016, 05:57 AM   #15
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Any concern about added weight of float?
Not really, this is light weight stuff. When it is back together, I will report back.
If you were to fix a bad float. First unsolder the little hole on the side, then cure the Gun Kote, then resolder the hole, otherwise internal air pressure will blow holes in the coating before it cures. I do have an old bad float that had so many holes when I finished soldering, decided it was not worth repairing. The entire bottom was rotting away. I just dont want that to happen to this other float.
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Old 04-27-2016, 09:14 AM   #16
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I made a discovery, you can not bake this at lower temps and expect it to be gasoline proof, etc...
Higher temp is critical, I did a gas soak test on the float and it partially rubbed off.

So I clean up a lawn mower carb and bake the bowl at 350 for 2 hours.
Ran the mower, sit overnight, pulled off bowl and coating is perfect, solid, can not be rubbed off, still shiny.

So all my future bakes will be done at 350 *F for at least 90 minutes, maybe 2 hours.
My oven is digital, but who knows how accurate is its temp.

Soldered floats at 350 , the solder is going to melt, so I dont think thats a go.
I may be possible to disassemble a brass float, clean off the solder, bake each piece.
then reassemble float and use the Gun Kote as a glue. then resolder the little breather air hole in the side. I might try that on an old rotten float I have. Of course if you can get a new float, then not worth it. Biit some floats are hard to find.



Cleaned up this carb in hot white vinegar.


The lawnmower last fall was only running on full choke, so E10 sitting over the winter caused that awful corrosion.
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Old 04-27-2016, 09:42 AM   #17
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This has been an educational little thread for me, thanks for the info. I work with some brand new systems but am responsible to maintain others originally made in the 1940's.
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Old 04-27-2016, 10:06 AM   #18
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This has been an educational little thread for me, thanks for the info. I work with some brand new systems but am responsible to maintain others originally made in the 1940's.
I like the stuff, seems to do what they say it does.

Another product is Cerakote, which may be less simple to use. May involve mixing on some of their coatings
Cerakote Coatings: Resources: Downloads

Here is an overview of the types they offer.
http://www.cerakoteguncoatings.com/r...es%20Guide.pdf

I was reading a blog put out by DuraKote, another coating company that examined CeraKote and there was no ceramic in Cerakote, it was more of an epoxy.

Seems to me some really good metal coating are now available for the DIY person which I like.
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Old 04-30-2016, 03:31 PM   #19
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I decided to coat these badly corroded and pitted Perko handles and two rod holders. Die cast zinc covered in chrome just does not last.
I ground these parts using medium grit ALOx grinding stones. Chrome is very hard metal.
I had lots of chrome left on the parts, and lots of pits, and some chrome bits flaking off.
It was rather a pain to grind. I ground out quite a few smaller pits on the handles.
The gun kote has sealed them all into a very smooth surface.

The rod holders, I also drilled the pits and filled with JB weld.
If you want JB weld to cure fast, simply bake it in the oven.

I sanded the rod holders smooth and sprayed all the parts with my leftover blue Gun Kote.
Then I resanded and coated and baked again. I pulled out the rubber inserts before working on these. The handles have about 3 coats.
I will put these back on and see how they hold up. I might leave these blue.

I can buy the 2500 metallic series, a brushed stainless or a silver color. They have a lot of metallic colors.

Here they are ground down, much smoother now.



Here they are after baking. Rod holders are visibly much smoother finish since I sanded and filled all the pits after grinding. The handles just were ground with medium grit stones. If they hold up in the salt, I could fill a few pits and coat again.
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Old 05-01-2016, 08:27 AM   #20
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Coated these Onan shielded spark plugs. They get hot and they rust. Paint wont stay on them.

I also repaired that old leaky float I kept for a backup, since these are impossible to get in this size now. My replacement works but is smaller in diameter then OEM.

I unsoldered both haves using a torch, cleaned, soldered up a few pinholes and sprayed the inside.
Then I used JB weld to glue the halves together. JB weld is not truly gas proof with E10, but with the gun kote, it should be ok. And the float is still light weight.
Sprayed the entire float with 3 coats. Baked at 350 for 90 minutes. Soldered the vent hole on top and tested in water and no leaks.
Next test is to leave it soaking in gas a few weeks.
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