Kinda like ospho

what’s that white stuff, looks like milk but i think worked better than ospho?

you mean this fine product?

I do not believe Loctite was on the jug. It came in white gallon jugs and was used for heavy duty stuff. The deck dept. used ospho to clean the ship before coming into port.
I’m not saying it wasn’t a Loctite product, (they may of improved it) but I think it’s been around quite a while.
Someone will remember it or i may have to go to the dark side where the deck dept. hangs out.



that’s the other stuff i was thinking about. That wasn’t in ol’ Allied Transportations budget!

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Corroseal is really good stuff.


what’s that white stuff, looks like milk but i think worked better than ospho?

This is it! Seemed to work best with International paint.

Naval Jelly?

pro-line (a brand of sherman williams products for marine use) used to make a product called rust buster. cant find a picture of it online though

bayrunner had the name of what I was thinking of. I’m not saying it was the best but it was good. some of that stuff you guys mentioned i’ve not heard of but it’d be interesting to do a comparison but out here in the PNW Mountains there isn’t much to practice on.
Thx, all

Researchers in Canada did a research paper on these products and Rust-Oleum Rust Reformer was the best. Not a massive difference between any of them though. I think adhering to proper preparation and application guidelines would make a bigger difference than which product you use.

Pro-tip for Corroseal. Fantastic product, but needs a fresh water wash after application before applying the paint.
Also, it is not compatible with all manufacturers paints.


The white stuff is a rust ‘converter’, En-Rust and Corroseal are two popular brands we use on boats.
Others have mentioned a couple in addition to those.
‘Converters’ are usually applied to bare metal after it’s allowed to developed a small amount surface rust, applied with a brush.
Ospho, Rust Rust Dissolve etc are phosphoric acid rust inhibitors, sprayed from a sprayer typically and primarily used for cleaning running rust and preparing larger areas for coating.
Converters and inhibitors have different purposes and neither one really is “better” than the other since they have their own applications.
In my own personal experience (about a decade and a half on deck), I have never really seen much difference in spots that were properly prepped/cleaned with no converter applied, versus spots that did following the instructions exactly. Take that for what it’s worth.


I don’t recall washing with fresh water after a coat. I was invariably in some dark corner like the reefer flat or somewhere and had to get a certain area done before i could leave. it’d be ready to paint the next overtime session. I remember a white ugly gooey stuff that was often times underneath a normal looking layer of machinery gray paint. I think it was some form of rust, maybe dissolving paint or something. it wasn’t good whatever it was!

I’ve seen people spray it on rust steaks with a hand pump sprayer then rinse it of a little later to try to clean the rust streaks but never noticed if it actually did the job or not. That’s not what it’s designed for though.

If you read the directions you’ll see it’s supposed to be applied (usually by paint brush but a paint sprayer would work) and allowed to dry 24 hours, not rinsed off, then painted over, and that it converts the rust into an inert substance.

Not in the same class as Ospho or similar rust converters and is perhaps outside this conversation are products like Unitor Metal Bright. I have seen it used (by the crew) as a paint prep besides just rust stain removal. The trouble with this stuff, without proper use and adequate flushing, it really screws up (streaking/staining) hull paint. Nothing like coming out of the shipyard having spent quarter million dollars on a fresh paint job only to see the sides of the ship discolored (white streaking) just a few months later.

Edit: We had a meeting aboard ship and it was agreed this would no longer be used or ordered. One C/M thought he knew better and tried to sneak in an order. Whenever I ran across it I would take it back to the stern and dump it overboard. Pissed him off, but he dared not mention it to the Captain or Vessel Manager.

It probably wouldn’t have been so bad if we had fish plates along the main deck and periodic offshoots to direct it off & away from the hull. We had rounded gunnels and anything on the deck would just wash off just roll down the sides.

yea, i’ve seen that but i don’t recall what yard they may of visited. I’m sure someone called the yard on a few of such paint jobs but can’t imagine the results of that “complaint”!!, … it got to where I dreaded going to a yard except for the inport stay and ‘free’ cash to blow.

I’ve read the manufacturer’s directions extensively for these prep products and coatings and have maintained several boats throughout the years ranging from 65 tons to 10500 tons.

Point being, these products are mostly garbage and you would be just as well off slapping Elmer’s glue on the prepped spots.

I said that’s what it’s typically used for because the intended use doesn’t work, I’ve tried many, many with several different ‘converters’ …Nine times in ten, you will get better results if you properly prep an area instead of leaving rust as they suggest and trying to convert it especially using Ospho which is just acid.

But you do you.


With all due respect to our fellow contributors, yours has to be the most sensible input thus far. I can only fault you on one point - I’d have to go with “ten times in ten”.

The secret lies here. Clean bare steel with adequate roughness, such that you could file your fingernail down by rubbing the nail on your prepared substrate, is what you seek. Do not rely on a bright, shiney surface, you need a profile that will be the foundational anchor that will tenaciously hold your paint scheme in place, just like dog shit on the bottom of your flip flop. Then, apply your anticorrosive to an adequate thickness by brush. The penetration offered by correct brush application is superior to any other method, including airless spray. Generally, depending on primer, brush will give you around 50 microns, so try for three coats, brush it in, don’t just lay it on. Your subsequent finish coat is almost purely cosmetic, contributing little in terms of steel preservation.

Weather conditions matter, beware the dew point in particular. In the marine environment, degrease and fresh water wash before prep and wash between coats, salt is your enemy.

Bottom line, if you would rather not repair the same area six months later, do the job properly first time around.

My spiel here relates to onboard maintenance. A drydocking specification is a whole different ball game.

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