Best Material for Undercoat Protection

fo4imtippin

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Jacksonville, FL
My bus currently has zero rust under it. Ill be rerunning fuel lines and cleaning up wiring to clear the frame rails. At that point, id like to protect the underside since it will be stored a few blocks from the Atlantic Ocean. Plan is to powerwash all the dirt and oil off it and wire brush any stubborn areas. What product would be best to spray on to protect it for the long term. Want to get this done before i mount tanks and underbody toolboxes.
 
My bus currently has zero rust under it. Ill be rerunning fuel lines and cleaning up wiring to clear the frame rails. At that point, id like to protect the underside since it will be stored a few blocks from the Atlantic Ocean. Plan is to powerwash all the dirt and oil off it and wire brush any stubborn areas. What product would be best to spray on to protect it for the long term. Want to get this done before i mount tanks and underbody toolboxes.

Whatever you end up using for undercoating, I'd start with a good layer of high quality primer, and let that cure for a few months first.
 
power wash, corroseal any rusty areas (put the whole gallon in a pesticide sprayer and got to town with it) at that point for undercoating your options are usually rubberized undercoating or fluid film.

With ruberized under coating (or rhino-liner) the idea is that they create a barrier to protect the steel. But if there is rust or moisture while you apply, you end up trapping that and it rusts behind the coating. Which can flake off.

Fluid film is an oil product, My understanding is that it "nourishes" the metal... Kind of like putting fresh grease on a cast iron pan. You do need to reapply this every so often. I have heard that folks will apply fluid film and then go drive a dusty dry road. Basically to cake the dirt to the oil and help form a sludge that keeps the oil in and salt off.
 
WD-40 is also a corrosion protection fluid film, but you would have to reapply it once in a while as it does eventually wash off if you drive in rain. You can buy it in gallon cans and use a sprayer.
 
https://blasterproducts.com/product/surface-shield/

Came out like 120 days ago, but its just flying off the shelf with a waiting list for the 1 gallon and 5 gallon pals. Previous integration "Heavy Duty Corrosion Stop Protectant" was already beating out most of the competition. Not sure if its better than fluidfilm gallon, but it beats fluidfilm in a can.
 
https://blasterproducts.com/product/surface-shield/

Came out like 120 days ago, but its just flying off the shelf with a waiting list for the 1 gallon and 5 gallon pals. Previous integration "Heavy Duty Corrosion Stop Protectant" was already beating out most of the competition. Not sure if its better than fluidfilm gallon, but it beats fluidfilm in a can.

"Extreme Moisture-Wicking Action" Huh? You don't want something that attracts and keeps moisture. You want something that keeps moisture out and off the surface. Something tells me the person who wrote the marketing gobbledigook doesn't quite understand what "wicking" means. Probably used it in the context of textile material in clothing, but that's completely different, as the point there is to pull the moisture that is already there away from the skin.
 
Yea... Basically it doesnt wash off in marine applications. And stays "wet" and hydrophobic longer, and longer "self healing and creep". Vs just turning to tar and kinda drying out. Still dont understand "Extreme Moisture-Wicking Action" since zero "water displacement" products do that, including this one.
 
Yea... Basically it doesnt wash off in marine applications. And stays "wet" and hydrophobic longer, and longer "self healing and creep". Vs just turning to tar and kinda drying out. Still dont understand "Extreme Moisture-Wicking Action" since zero "water displacement" products do that, including this one.

I guess someone must not have been paying attention in 6th grade science class.
 
Maybe the marketing guy used a lot of wd40 to "get" water out of alot of flooded connectors. "this wicks great!".
 
Maybe the marketing guy used a lot of wd40 to "get" water out of alot of flooded connectors. "this wicks great!".

LOL! If you throw WD-40 on a wet surface it actually traps the water under the film. You're supposed to let the surface dry first. :rofl:
 
I would think por15, let it fully cure for a while. then an application of fluid film or NH oil before each winter if driving . Fluid film stinks, I get my cars sprayed every year, we dilute it a bit with bar oil to help it flow a little better. The Nh oil seem to be all the rage currently and i think i may go with that this year as i am behind on getting my truck sprayed.
 
My bus currently has zero rust under it. Ill be rerunning fuel lines and cleaning up wiring to clear the frame rails. At that point, id like to protect the underside since it will be stored a few blocks from the Atlantic Ocean. Plan is to powerwash all the dirt and oil off it and wire brush any stubborn areas. What product would be best to spray on to protect it for the long term. Want to get this done before i mount tanks and underbody toolboxes.
Corroseal and once cured I used flexseal.
Could use my bus as an ark if needed...lol
Cheers
 
I know of a few people who have been fluid-filming their work trucks (dump trucks, snow plow / salt trucks) for years.. they apply it right before the salt flies each year and it lasts the winter season.. their salt trucks have held up extremely well and thats in northeast ohio where it snows every other day in a normal winter..



I dont know if they drive a dusty road after application or not but seeing early to mid 00's trucks that spread salt, go in the mud in summers for tree / landscaping, and plow snow with no rust says to me the stuff works..


you should be careful when applying it to avoid rubber hoses and lines like for Hydraulics, A/C, flexible brake lines etc.. it is a petroleum product so it can degrade rubber.
 
I enjoyed this persons testing on various products last time i was researching this topic..


additional homebrew solutions and myths


3 year follow up with fluid film....


also seems this youtuber gave the PB Blaster product a try.

 

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