Ospho rust treatment

[widowmaker77]

Has anyone used Ospho to treat/kill rusted panels with? I’ve been doing some research on products like Eastwood rust encapsulator and similar products. I found some good reviews on this ospho stuff and I’m curious if anyone here has used it. It seems to be a good bit cheaper that the Eastwood stuff.

 

[laserfish]

Used the Eastwood under the hood 10 years ago and it is still holding up great.

 

[trailerjack]

I have heard that with ospho, you apply it and then sand it to get epoxy primer to hold better.

 

[AC932]

I used Ospho on the entire underside of my truck. Sprayed it on with a hand-pumped pesticide sprayer. Would not recommend it for something that's supposed to be visually appealing (leaves a kinda weird texture), but it's perfect for chassis and under-body. I undercoated over it, and that combination has held up pretty well through the snow and salt.

It does a good job of getting rid of existing rust, but if you don't cover it with paint or something, the metal will start to rust again after ~6 months exposure.

It's also pretty good at treating paint chips that rust over, cuz (in my experience, anyway) it doesn't mess too much with the paint surrounding it (As long as you don't over-do it).

Also, when applying it, wear a dust mask (or better, respirator) and long sleeved clothes and gloves. Stuff really burns your skin and is kinda painful to breathe it. It will also react with concrete and form a white powdery substance, so don't be too attached to your floor.

 

[widowmaker77]

I used Ospho on the entire underside of my truck. Sprayed it on with a hand-pumped pesticide sprayer. Would not recommend it for something that's supposed to be visually appealing (leaves a kinda weird texture), but it's perfect for chassis and under-body. I undercoated over it, and that combination has held up pretty well through the snow and salt.

It does a good job of getting rid of existing rust, but if you don't cover it with paint or something, the metal will start to rust again after ~6 months exposure.

It's also pretty good at treating paint chips that rust over, cuz (in my experience, anyway) it doesn't mess too much with the paint surrounding it (As long as you don't over-do it).

Also, when applying it, wear a dust mask (or better, respirator) and long sleeved clothes and gloves. Stuff really burns your skin and is kinda painful to breathe it. It will also react with concrete and form a white powdery substance, so don't be too attached to your floor.

Thanks! This is what I’m planning on doing with this stuff. I’m going to coat with ospho then I plan to coat with raptor epoxy primer and finally raptor liner. When you coated over it, did you have to sand it or wash it to get the coating to stick?

 

[widowmaker77]

I have heard that with ospho, you apply it and then sand it to get epoxy primer to hold better.

I’ve read that also but the instructions from ospho say to wash it. So I’m not sure which is right

 

[AC932]

I didn't sand or wash it, just let it dry, used a dust-broom to sweep off the white powdery stuff that showed up in places, and undercoated over it. That said, I imagine sanding and/or washing would only help stuff stick to it.

Just checked their website, it says to "Brush off any loose powder and wipe down with Mineral Spirits before painting".

 

[widowmaker77]

I didn't sand or wash it, just let it dry, used a dust-broom to sweep off the white powdery stuff that showed up in places, and undercoated over it. That said, I imagine sanding and/or washing would only help stuff stick to it.

Just checked their website, it says to "Brush off any loose powder and wipe down with Mineral Spirits before painting".

Thank you! I appreciate the info

 

[67RT]

I applied mine to areas of underside with surface scale with a spongy wet sanding block.. Got it soaked and scrubbed it in. Do not get this stuff on you.. Safety goggles, respirator, etc. It will change color of non clear coated paint too.

 

[diggs00]

https://www.youtube.com/watch?v=-yA8q4K-_Bo

You should rinse/neutralize it before applying primer/paint.

 

[widowmaker77]

Thanks guys for all the help!

 

[Pa PITT]

I'd never heard of that Ospho stuff but any time rust comes up my neighbor says to use it.
.. It's got to be good as much as he wears my butt out over it.

 

[ransil]

Isnt ospho just phosphorus acid? Which can be bought for 1/4 the price

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[widowmaker77]

Isnt ospho just phosphorus acid? Which can be bought for 1/4 the price

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Yep. A gallon jug of it cost me $27 at my local ace hardware. I’ve only heard good things about this stuff.

 

[McLeod]

Even cheaper at Home Depot.
https://www.homedepot.com/p/Klean-S...Metal-Prep-Rust-Inhibitor-GKPA30220/100406369

It has worked good for me.
Put it in a garden sprayer and go to town. I try to stay away from wiring looms and the such but every thing else gets hosed down.
Don't let it drip on your concrete though.

 

[lilthom]

Do over.

My body shop used it to prep the inside of the cab and bed for spray liner. Apparently he didn't read the fine print as far as neutralizing it afterwards. Within days after the liner was sprayed it started popping loose in the areas he sprayed the phospho. He gets to do it all over again now.

 

[unimogger]

I've used it, and for some things it's ok. For instance, when sandblasting or grinding and you find some deep pits or a corner that you're not sure you can get all of the rust out of.. that is where Ospho works well. Treat those spots, and then neutralize and rinse before using a good primer sealer. For this it works well.
If you just hose it over rust, and expect the results to last you're kidding yourself. It's main active ingredient is Phosphoric acid. The reaction with iron oxide is a double displacement reaction that yields iron phosphate and water. But unless you have just the correct ratio of acid to rust, you will probably have extra acid, which is why you have to neutralize afterwards. Leftover acid can cause all sorts of issues, and it will start to rust again..

 

[Toyaddict71]

I did the same process on my undercarriage and frame a few years ago. It still looks great. I also used this spray inside the frame rails. It has a hose that fits inside the frame and coats it with inhibitor.

Eastwood Internal Chassis Frame Green Coating 14 oz with Spray Nozzle Remove Rust Corrosion. I got it on Amazon.
Make sure you use a tarp or something under neath because it is a mess.

 

[tampabronco]

Ospho is good stuff

I've used and it worked well for me

 

[widowmaker77]

Thanks for all the feedback guys. I’m wanting to spray all up in the rear quarters mainly and then I bought the anti corrosive epoxy primer from raptor liner to coat all these areas. Then my plan is raptor line the whole underbody