Coal Tar Epoxy Undercoat

KJs JK

New member
Hello everyone, I wanted to document my experience with this industrial anti corrosion coating called coal tar epoxy. I bought a JK 2dr two weeks ago, and then drove it to my warehouse and parked it. Then i spent a week underneath it applying this epoxy coating to the frame and up the rockers. This was the first vehicle i have owned that wasn't rusty enough to attempt a preservation. The JK came from down south so the frame looked great.
I thoroughly washed the frame and undercarriage with degreaser and then let it dry for two days. In the mean time i purchased a cheapo undercoating gun from amazon with the intention of ruining it completely, which i did. Now the coal tar epoxy is a relatively cheap coating that is the trashy cousin of rustoleum's 9100 series, which was a little out of my price range at $200 for two gallons, one activator and one base.
The coal tar epoxy i picked up from McMaster-Carr and it came in a kit with a gallon of base, and a quart of activator, which means it mixes at 4:1 ratio. I had to sign government release forms to purchase it. Also, it can be thinned with Xylene/Xylol as with all epoxies, which is some nasty stuff in and of itself. Coal Tar Epoxy is used for corrosion resistance on bridges and pipelines that are submerged in salt water, so the salt up here in OH shouldn't stand a chance. But this stuff is gross, it will ruin everything it touches so i got a tyvek suit and some gloves and goggles and went to town.
The mixing was straight forward with a half inch drill and mixing bit. The instructions only say to prep the area with degreaser and make sure it is dry. So i loaded the gun up and clogged it instantly, couldn't even get it to work by thinning the paste beyond recognition. With the gun idea shot, i got to work painting with a 2 inch brush, and over the course of 3 days i got every part i could reach.
The coating hardened into a monster, i can hit it with a hammer, but it was so thick that my hands were cramped and wouldnt work properly for a week, and it left brush marks in everywhere. So i took some rubberized undercoating and just put a quick coat everywhere underneath and over the epoxy. It took away the glossy look which was good because it looked like crap with the brush marks.
Then to cap it all off, i filled my frame with fluid film to keep it from rusting from within. All in all, it was gross, nasty, time consuming and tiring, but i'm glad i put all that work in because i hate rust with the fire of a thousand suns and i really hope this works.

undercoating med.jpg
 

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Caught the Bug
I just use mobile 1 synthetic oil to coat my undercarriage.

Stop over and give us a wave if not a Vendor trying to pimp your juice.
 

KJs JK

New member
My apologies for not introducing myself, I just traded my WRX for a JK two weeks ago and I absolutely love my jeep. It came from down south so it wasn't very rusty, and there was only 32" tires on it and no tow hitch. Everything is clean and it actually goes pretty fast. I'm happy with the 3.8l since Chrysler has been making it for 25 years and it is simple. Variable Valve Timing is black magic to me. The manual shift is smooth so far although 6th gear is useless on the highway if any sort of an incline appears, and reverse should be where BMW puts it next to first, to make it easy to rock from reverse to 1st or 2nd.
Not sure how to wave or say hello or any of that so please excuse my ignorance as i get used to the forums. Hope to provide as much info as i receive and thanks for the warm welcome.
 

KJs JK

New member
Welcome work WAL

I've heard you can just use old motor oil to coat your frame :cheesy:

The tractor dealerships around here hawk this stuff called Fluid Film which is a lanolin based oil coating that sticks really well, and I plan on coating the entire underside every year with the stuff.
A lot easier to get under my Jeep to apply it than it was to get under my Subie.
 
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