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deadbodyman 03-30-2010 07:39 AM

The Ospho Solution..(rust removal)
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This is the start of a thread dedicated to successful rust removal using ospho,a water based phosphric acid product I've been using professionally for many years.
Ospho has some advantages over other methods, mainly a DIY can do it at home inexpensively with little mess,fairly easily.
I'll try to answer any questions and offer some advice on the successful use of this product.
.....First,I'll start with the most common use : To remove surface rust That has accumulated on unprotected steel....Then heavly rusted and pitted metal,and using it to prevent surface rust of freshly stripped steel...
The pics below show the trunk floor and wheel wells I made for my old car.After making the pieces and screwing them together ,it got cold out and I put the car up for a couple months and the steel got pretty rusty.
In the interest of time I'll just do a spot to show how its done and what Materials you'll need.Bare with me I'm a newbie with the computer.

deadbodyman 03-30-2010 07:48 AM

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You'll need a quart of Ospho, available at any body & paint supply store,some red scuff pads Pt#07747, rubber gloves and paper shop towels.

deadbodyman 03-30-2010 08:15 AM

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I prefer a using a pump spray bottle (like an old windex bottle) but this will do for now.Apply ospho liberally and scrub it in with the scuff pad, keeping it wet, then wipe off the excess with the towels.let it sit 24 hrs.
This is pretty heavy, so If you want to clean it some more, just sand it down with 80 and You can reapply it a second time or as many times as you want.
I'm doing this outside like most of you will be doing.heres a picture of what it looks like after its dried compared to what it started off as.
I'll be posting much more later tonight, on other uses and prepping for primer.. This will protect the metal from futher rusting until I'm ready, even being outside.

farna 03-30-2010 06:29 PM

Great job so far, can't wait to see more! I've used something from the hardware store called "The Must for Rust" that is similar, probably a watered down version of Ospho. Now that I know what to look for an where, I'll use Ospho instead!

Hwyhogg 03-30-2010 06:52 PM

Thanks for taking the time to post the videos....A video is worth a million words....

Old Fool 03-30-2010 07:03 PM

In the quest to get er dun, why not first hit it with the da, then the Ospho?

I like to let power tools do most of the effort, if that works with your process..

deadbodyman 03-31-2010 07:48 AM

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Originally Posted by Old Fool
In the quest to get er dun, why not first hit it with the da, then the Ospho?

I like to let power tools do most of the effort, if that works with your process..

In this situation,(surface rust), sanding wasn't necessary before applying the ospho. In the video it shows just how quick it works..
.However in extreme cases It will be necessary to sand or wire wheel the surface first. Coming up, is a car that had a vinyl top that is extremely rusty with pits but I'm saving the best for last....Bear with me..

deadbodyman 03-31-2010 09:29 AM

If you decide to strip the old paint from your car and start fresh,I'd suggest stripping the whole car at once and then working one one panel at a time priming each panel as you go.
This takes time and your car will start getting surface rust,so what I do is apply the Ospho to the whole car immediately after stripping it really doesn't matter what method of stripping you use ,media blasted ,sanded or chemical strip,'s a short vid of the prep process.
Ospho can be a big help getting the steel extra clean and keeping the bare metal from rusting until its primed,it leaves a protective primer coat when it drys.This hood had very little rust at all but I'm doing this outside so as soon as I got it stripped, sanded and cleaned I applied the ospho because I couldn't immediately prime the steel...
Reason: I don't like mixing small amounts of primer,I'll wait until my motor cycle tank is ready and then I'll prime both at the same time....

deadbodyman 03-31-2010 09:48 AM

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Sometimes if there's to much excess left on you'll see streaks like this.I like to reapply a second coat... just repeat the process (see pics below).
Lacquer thinner wont remove them and they must be sanded before priming I just apply a second coat and forget about them,I'll get more into that later.(Prepping for primer)

deadbodyman 03-31-2010 09:55 AM

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It rained the last two nights as you can see there's white dots but no rust yet..
If I was going to prime today, I would just sand with 180 and prime.but I'm in no hurry... maybe tomorrow

farna 03-31-2010 12:59 PM

That's basically the directions I recall from "The Must for Rust". If there is a lot of white residue after drying, apply another coat, let sit for a few minutes but DON'T let dry, then rinse off. The acid will soften the residue and the excess will rinse off. A small amount of residue is just prepped over. I'll wait for deadbodyman to describe the pre-prime/paint procedure -- I have to admit I've forgotten!

If you just want a bit to try see if the local Ace hardware doesn't have "The Must for Rust". I've bought it at K-mart too. A lot cheaper than the Ospho, but it's a bit weaker too. I bought it in a ready to use pump bottle. It's basically the same as Ospho, just weaker for the DIY homeowner, not professionals. Other than that all procedures are the same. Read directions on the label!

chas350 03-31-2010 06:20 PM

DBM, you don't rinse this with water after application?

I used Metal Ready on some minor rust once on my van before epoxy and SS. 2 months later I noticed the paint bubbled in the same area's I used the Metal Ready, no where else. That was a year and 2 months ago, now I have rust spots all over the Metal Ready area. Shortly after this happened I read on the SPI forum about this exact problem being caused by acid metal treatments.
So now I am a bit gunshy about using any type of acid.
I was careful to rinse the acid off before it dried, what did I do wrong?
Have you ever had this problem with Ospho seeing its an acid?

deadbodyman 03-31-2010 07:33 PM

All I've ever used has been Ospho.I've never rinsed it off or touched it with water I just let it dry.the heavier spots where you see the streaks stay tacky longer than the rest and if you were to prime over them while tacky, I'm sure there would be problems.
When I'm ready to prime, I just sand with a da or scuff pad and wipe off with wax & grease remover.I'm pretty sure I'll be priming tomorrow so you'll see the whole process.

The way I do it is not quite the way the directions say but I feel it's even better.
After the primer has cured ,I'll do some adhesion tests.
My little shop truck was stripped and painted using the same method,well over ten years ago and still looks like its fresh paint.I'll post a few pics of that too.
Please keep in mind there's many acid products out there.This is just, about Ospho,I have no idea about any others,including Naval jelly.

chas350 04-01-2010 10:25 PM

Ok, do you sand the film of Ospho off? or just scuff?

deadbodyman 04-02-2010 07:02 AM

Chas350,You can do it either way.
On exposed surfaces that 'll be painted ,I sand the coating to give the epoxy something to bite into but I dont sand it off. I do sand a little extra to remove the rough streaks left by to much excess
.On other areas that wont be exposed (like wheel wells inner rockers etc) and irregular surfaces like door jambs... I scuff insted of sand..
Once your ready to prime,you can sand All the coating off if you like,its already done its job protecting against further rust.
Heres the video showing how I sand with 180 then wipe off the grayish powder with wax & grease remover then prime.The glare is bad but you can see how little time it takes to prep.
Today I'll sand and prime the other side of the hood without Ospho and do a couple of adhesion tests on both sides when everything is cured. Then it's on to the real heavy rust on that Furys roof

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