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The Ospho Solution..(rust removal)

353K views 664 replies 61 participants last post by  Lizer 
#1 ·
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.
 

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#152 ·
DanielC said:
I live in Portland, Or, and have been trying to get Ospho locally. I finally found it at a "Wilco", a local farm supply type store.

I will see how it works for me.
Whatcha workin on Dan C ? Take some pics if you can and post your results.
Nobody disputes how well it removes rust and protects metal against surface rust ,I guess the real question is the adheasion of the epoxy primer when Ospho is used, so take particular care when preping for primer..
BTW,just curious I assume you bought a qt ,how much did it cost at that hardware store...The prices seem to vary quite a bit from coast to coast.
 
#155 ·
I have been doing some work with the Ospho. I think I an getting a good idea of how to use it in my situation.
It seems to work pretty good, like most produces with phosphoric acid in them. Is it better, I do not know yet.

About the controversy of using a acid type metal conditioner under epoxy primer. It appears with some primers you can, other primers you cannot, I think it boils down to this.
READ THE DATA SHEETS!
If you are using a primer with the word "etch" in the name, the primer probably has a acid in the primer, and problems may occur if applied over "conditioned" metal, without a through cleaning, or neutralizing, and sanding. By "conditioned" metal, I mean steel that has been cleaned with Ospho, PPG metal conditioner, Dupont metal conditioner, Naval Jelly, or even Coca-Cola, all these products contain phosphoric acid.

However, some epoxy primers may work just fine on Ospho treated metal. I have been using PPG DPLF, with 401LF hardener.
In the data sheet for PPG DPLF, is the phrase:
"chemical treatment or the use of a conversion coating will enhance the adhesion and performance properties of the finished system"

Below that, after a direction for aluminium, is the phrase:
Prime carbon steel immediately after cleaning.

But I am still in the remove rust stage. What I have been doing is using the Ospho, on some thinly painted surfaces with a fair amount if rust. The Ospho may have the advantage of not needing an immediate covering with primer. When I am ready to prime, sanding, or another treatment and immediate cleaning with the Ospho, or just "normal" metal conditioner.
 
#157 ·
But I am still in the remove rust stage. What I have been doing is using the Ospho, on some thinly painted surfaces with a fair amount if rust. The Ospho may have the advantage of not needing an immediate covering with primer. When I am ready to prime, sanding, or another treatment and immediate cleaning with the Ospho, or just "normal" metal conditioner.
When I'm ready to prime I always sand with some 180(or a scuff pad for irregular surfaces),clean with W&G remover and prime.
 
#159 ·
Hey DBM, you must remember me from a couple of years ago. O'm glad you're still atound on this forum. Just out of the blue I decided to Google ospho today and it looks like it's now available in Canada. Caswell Canada :: REPAIR PRODUCTS :: Ospho Rust Inhibitor :: Ospho Rust Inhibitor
Is it the one I need, the same as in U.S.?
For the meanwhile I used naval jelly and it works fine. I think I use it similarly to how you use ospho. Only that I apply a really thick coat and leave it overnight or for a few hours. I don't keep it wet by spraying water on it. Then I remove all the residue (white film/sand-probably iron phosphate or rust leftovers) and reapply until all rust is gone. Every time I wire brush the area and reapply naval jelly. It removes all the rust 100%. Then I wire brush or sand the area and apply POR15 since the metal has already been etched by naval jelly (actually I use KBS Coatings instead of por). In any case I use por because I couldn't find an epoxy primer that was recommended to me on this website. So hard to find anything good in Canada.
Now if I order that ospho, what would be the difference in results that I get by using naval jelly? You said that you use it to remove rust but naval jelly removes it as well no problem.
So what you do is you use 180 sandpaper to sand the metal after all the rust is gone with ospho? Why do you use wax and grease remover after that? What's there to degrease if by removing all the rust and sanding the bare metal you already removed a thin layer of metal off the bare metal. Anything that might have been on the metal is removed/scratched off/ sanded away. I wonder if I'm missing something.
 
#162 ·
Hey DBM, you must remember me from a couple of years ago. O'm glad you're still atound on this forum. Just out of the blue I decided to Google ospho today and it looks like it's now available in Canada. Caswell Canada*::*REPAIR PRODUCTS*::*Ospho Rust Inhibitor*::*Ospho Rust Inhibitor
Is it the one I need, the same as in U.S.?
For the meanwhile I used naval jelly and it works fine. I think I use it similarly to how you use ospho. Only that I apply a really thick coat and leave it overnight or for a few hours. I don't keep it wet by spraying water on it. Then I remove all the residue (white film/sand-probably iron phosphate or rust leftovers) and reapply until all rust is gone. Every time I wire brush the area and reapply naval jelly. It removes all the rust 100%. Then I wire brush or sand the area and apply POR15 since the metal has already been etched by naval jelly (actually I use KBS Coatings instead of por). In any case I use por because I couldn't find an epoxy primer that was recommended to me on this website. So hard to find anything good in Canada.
Now if I order that ospho, what would be the difference in results that I get by using naval jelly? You said that you use it to remove rust but naval jelly removes it as well no problem.
So what you do is you use 180 sandpaper to sand the metal after all the rust is gone with ospho? Why do you use wax and grease remover after that? What's there to degrease if by removing all the rust and sanding the bare metal you already removed a thin layer of metal off the bare metal. Anything that might have been on the metal is removed/scratched off/ sanded away. I wonder if I'm missing something.
SPI epoxy primer is available in Canada.
Give them a call and they'll give you contact info.

Do not use a POR type paint as your primer. If it peels of in sheets later, you'll be sorry.

Taking off all the black is good as there will still be rust underneath, on the heavy rust areas. Repeat as you're doing until all rust is gone and then use epoxy primer. Since the rust is gone, you don't need to use and "magic" paints as a base.
 
#161 ·
oleg, you use a wax and grease remover before any painting operation. Even fingerprints will cause problems under the paint, the wax and grease remover (or just wipe with mineral spirits or paint thinner) removes every trace that could cause problems like "fish eye".
 
#163 ·
I understand that but if you wire brush and sandpaper there is nothing left, no fingerprints, nothing. Then wipe it off with a clean towel. Not only that, but I also heard that if you use a paint thinner etc. it will leave a thin film layer when it dries which will cause serious adhesion problems.
 
#165 ·
Not a cost issue at all, just trying to make it as simple as possible. Less steps, less chances of screwing something up. Does this wax remover leave any sort of film behind it? Do I need to rinse it with water? If so, it's an additional complication and I don't want to complicate the job unless it clearly affects its quality. For example if rust was removed near seams/crevices and I have to spray water to clean the wax remover than it can get inside and take days to dry.
 
#166 ·
It doesn't leave a film behind.
Its specifically made for this use. You use it on a lint free cloth and hand wipe, no rinsing.

Google it or search this site. You're on the right track about doing things correctly. Please remember to forget about the POR style paints if you're already at bare metal. They don't stick well.

Epoxy primer will be sold locally also at automotive paint suppliers but I've never heard more positive comments about epoxy than I hear about SPI.
 
#167 ·
Thats the stuff.The only difference in Ospho and Navel jelly as far as I can tell is Ospho is a lot more concentrated and works faster.When I remove rust I pour or spray the Ospho on and start wire wheeling the rust off right away.If you see any areas turn black they'll need a second application ,the black is rust being converted and thats not something you want.I 've done as many as 4 apps on some cars...
after I sand with 80-180 I'll blow the car off with air then use thee W&G finger prints, sweat,contaminets from the air supply theres a hundred things that can get on the car The W&G is the way to prep before priming..After you sand a car for paint you would want to W&G ,right? when I prep a car I always W&G everything ,to clean the car and make the tape stick better.After taping and right before paint it gets one last shot with W&G ,You should always ,always ,always W&G just before spraying anything.it's good insurance.theres no such thing as using too much of the stuff...and the metal can never be TOO clean.
I really wouldnt use POR products as they are converters and removing rust is always the goal...
As far as epoxy primer goes I really like and prefer SPI but I've used many brands in my time, they all work but SPI seems be stand way above the rest and the owner (Barry K.)is always just a phone call away if I ever have any dumb questions about his products...
I'll try to get some better vidios up but I need a good vidio camera that is idiot proof and a little tougher than my last one that was dropped a few times and quit on me...I'm thinking about getting a new one for my wifes birthday so I can get her old one...so far she wont even let me touch it... for now I'm cameraless but I'm working on it..
Good luck with all your projects guys.... Hey how about some pics of your results using Ospho or Navel jelly in the meantime....
Its good to hear that Canada has the two products That I concider the best out there just in case I ever decide to pack it all up and leave the sunny ,snowless state of Ga.... I still have quite a few relitives in the great white North
 
#171 ·
appaently the guys at skyco have intrests in hotrods and got in touch with me after reading this thread.....I had some interesting conversations and one of the things I was told was the auto industry only accounts for less than 1% of of its sales...its mostly sold to guys like you working on big projects that buy it by the 55 gal drum.
 
#172 ·
Well Mike, I got my Ospho in the mail today, I am going to finish reading this entire thread before I jump in, but I will be trying the DBM rust method.

Brian
 
#173 ·
I was thrilled by the way finding it on line thru Amazon for $10.36 a quart. I went ahead and got two quarts with shipping for the same price as one quart here in town. And I can't even guarantee that because they had none in stock and said that they would have to order and sell me a case of 12 but would ask the manager. After finding it on Amazon I never went back. Amazon.com: ospho rust treatment

But after googling it and looking all over this was the first site that had it singular, everywhere be it a quart or gallon only sold it by the case. I searched all over town at the McHome stores and even at my beloved REAL hardware store here in town, nothing.

So I was thrilled to find it on Amazon and wham, here it is ordered on the first of July, it's in my hand. I think the rust was ok waiting 9 days for me to get it. :D

Brian
 
#175 ·
Would the Ospho be a good solution to the Dodge Peel from the 90's?


From what I read, is this the right approach to your way?
-Spray Ospho on (or wipe?)
-Angle Grinder with 5" cup wheel
-DA with 180 to get the Ospho off (no rinse)
-Wax/Grease remover
-Epoxy Primer
-Fill any pits
-Sand
-Epoxy Prime again
-Sand if needed
-Color
-Clear

Here's what I'm talking about:




Everyone's pretty familiar with this I'm sure.

Then this caught me a little off guard. Is that a sponge between the wheel arch and the wheel well? There's one on both sides and it looks factory to me. Was this a planned water retainer? I don't get why the sponge is there. Maybe it's to prevent rattle? Either way it doesn't look good as far as rust is concerned:
 
#178 ·
One more post on proper way to treat and I will stay away from this.

Acid can only be neutralized while wet and all you need to do is take a clean rag with water and wipe off and dry.
If it has dried, retreat with itself and let set 30 seconds to one minute and wipe off with water as above.
Then da with 80, wash with wax and grease remover and you are ready to epoxy.

A note about sanding, that is very risky sanding an acid film as test have shown at best you end up with 40-60% adhesion.
 
#180 ·
A note about sanding, that is very risky sanding an acid film as test have shown at best you end up with 40-60% adhesion.
Not according to my own test..I tried to scrape it off with a razor scraper and couldnt so if thats 40-60% adheasion thats pretty dang good ...Ive also treated one side of a hood and not the other, I've done all kinds of tests since this thread started...If I was having adheasion problems not only would I know about it I certainly would stop using it or follow YOUR instructions. Barry your a great guy and you've been a big help to me with all kinds of paint questions but I dont think we'll ever see eye to eye on this mainly because of all the paint and body products I've been using since 1976 ospho is the ONLY one that I still use and as hard headed as I know I can be If I had any doubts what so ever I'd say so...how ever wouldnt some litnus paper show if wiping as actually neautralized it? it seems to me that after the first wipe a wet towel would do anything...
This has been interesting but I gotta go right now ,I'll be back....
 
#179 ·
Leta address this neautralizing issue. theres two mabee three reasons to use ospho....1st would be to remove rust which it does very well.....2nd to protect bare metal from surface rust which it also does very well....3rd to etch metal or get metal super clean...
I think we all agree that it does all three very well.. So I have slightly revised my own proceedure by sanding it off completly when its done its job and no longer needed this way even if it was applied wrong or to much was left on and let dry sanding it off seems like the best way to use it that everyone can easily do so I started sanding it off a few panels or even one with 80 grit (whatever I feel I have time to do that day) and and epoxy priming what I sanded this is something EVERYONE can do even if they have never done it before....and even if it takes them two days to sand a fender...

Now 1st of all if I was to wash it off (neautralize it) then it wouldnt prevent surface rust any more and thats a big reason for using it in the first place.So you absolutely want it to dry..

2nd lets say your disolving the rust and using the wire wheel ,getting it all out of the pits and everything is going well, the rust is gone, there will always be tiny microscopic traces left (even if you sandblasted) the ospho will convert whats left and as much as I hate converting rust I feel its better than nothing and its fine when your talking microscopic traces...washing it off while its wet would leave it unprotected and we all know what happens when you put water on rust or bare metal...so the whole idea of washing it off (neautralizing it) makes absolutely no sence to me at all. Sorry Bear...mabee you could explain it so I could get a better understanding of the whole deal. but its my understanding that you cant neautralize acid with water you can only dilute it ,water itself is acidic you would need a base to neautralize acid ...wouldn't you need something like baking soda if you truely wanted it neautralized ???????
 
#201 ·
but its my understanding that you cant neautralize acid with water you can only dilute it
YES!!!!!

water itself is acidic
ABSOLUTELY!!!!!! The water I pH in my lab comes in around 5.5 to 6. Though tap water can tend to run a little more neutral or basic, depending on how much mineral it as in it, as these tend to have some buffering capacity and are a bit basic. The more pure your water, the more acidic it tends to be.

you would need a base to neautralize acid ...wouldn't you need something like baking soda if you truely wanted it neautralized ???????
FOR SURE!!! I can't speak to how wise it would be for a paint system, but the only way to really neutralize an acid is through a base. Water only dilutes it--or in nerd speak--reduces the acid MOLARITY (fancy term for chemical concentration). Now a very dilute acid still has a very low pH, even if diluted in LOTS of water.

I work with acids and bases every day in my lab; they're one of the most fundamental reagents as pH is so important in so many processes. And every one of them get diluted quite a bit in water. Needless to say if that water were neutralizing it I wouldn't be getting very far in my experiments :cool:

I think the reason it's state that the water neutralizes the Ospho is because it's assumed the water is diluting the acid to a reasonable content. I'm just not sold on it though. It takes a LOT of water to dilute an acid to the point where the pH significantly increases.

For those that are really curious about this--especially Brian since he's an aspiring Jr. Scientist with all his experiments he's always doing (and btw Brian, putting a pH strip against the metal wouldn't work well, it MIGHT, but it's not the way they are supposed to work and may not give an accurate read.)--get hold of some pH strips, and pour a cup of water in a jar or something with a lid. Take a baseline pH reading with a pH strip. Then add a drop of Ospho to that cup and see how much it lowers the pH. Mix real well by inversion before taking the pH reading.

A second experiment would be to take a small volume of Ospho, maybe a fraction of an ounce or something equivalent to what you might have on a panel, and take a baseline pH reading. Then start adding water, and continue to do so until you've reached a near neutral pH. This would give you an idea of how much water is really needed to 'neutralize' it.
 
#196 ·
You should always follow the tech sheets if you the best results but you dont want to follow Duponts tech sheet when using PPG products, do You ??? why even bring it up..Ospho isnt made by either company if it was it would probably cost 50.00 a quart....:confused: obviously You havent read the sheets for ospho or is that something new they added....
 
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