PHOSPHORIC ACID - a pictoral

Hence MY confusion.
In the past I used to do it that way, but it was just small spot-rust repair. This is the first time I ever coated an entire body with it.
My plan is to look for a primer/sealer that says it'll work with the OSPHO and leave it at that.

 

I've treated an entire panel with Ospho (let it dry).

Then scuffed it with the red scotch brite, took paint fine, paint is holding up well.

Single stage paint, put on with a spray can, stands up fine to the salt at Bonneville just fine.

 

HI, Nexxussian, A little trick I found is if you make up a 50/50 solution of metal prep and water, spray on previously treated area, let set for awhile then wipe off. The previous coating will reactivate and wipe off. it may take a few treatments like this. I even go down to 1/5 (1 acid/5 water) to help get it out the pores of pitted areas. A final was of warm water & baking soda helps nutrealize any acid in hidden areas.

 

Thanks.

I didn't want to remove the coating though, just rough it up a touch so the paint would get that much better chance to stick.

 

I work in a chemical plant which uses large volumes of phosphoric acid.

In a million years I wouldnt put it near my vehicle or even have it on my property.

No matter how hard you try you will not get it out of seams and folded edges etc.

Months or years later big ass rust problems will appear. I see the damage it causes on a daily basis.

Dangerous shit!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

If you dont use a face sheild or gloves your an accident waiting to happen.

 

Ratman, phosphoric acid has been used in the automotive industry for years and years. DuPont Metal Etch is phosphoric acid. That was the first I used of it, probably 25 years ago.Since then I have found my own acid without DuPont charging me extra

 

so what about body fillers over this?
Ive got the typical rust specks in little divets (mostly where the old stainless trim used to be). The car is stripped to bare metal and I was looking to "treat the rust specks before I do any skim coats of filler.
I use Rage gold filler and was wondering if any one has gone this route?

Thanks, Jeff

 

Here is how I do it on my restos. I treat the rust with acid. I then cover with two coats of Master Series. I follow with epoxy primer and block sand after curing. Typically there are no pits left. If there were, I would decide if more epoxy would handle the pits of a slim coat of filler. I keep plenty between the old poor condition metal and the filler. There are plenty of ways to do this I'm sure, but this is what I have found that works great.

 

I've used Ospho and Ospho type products for years but usually use it a little different than most of the posts here. If a car has surface rust I simply use a scotchbrite pad after brushing some on an area, and scrub until the metal starts becoming shiny. I don't let it dry, but I use a clean cloth and wipe that area clean. That way I get no white powdery finish to it, just shiny metal with somewhat of a protective coat on it.

The metal will still rust if you touch it, but if you stay away from it you can store the car (indoors) for months or years at a time without it rusting again. I did the 46 Ford my Son now has probably a year or two ago that way and it is still rustfree.

A side benefit is that the acid really cleans up aged paint great. It removes the top layer of oxidation and makes it look somewhat fresh. I wouldn't do that on a good paint job, but on one that you wanted some patina on it does a pretty good job.

As far as the comment that was made about not letting it near a car, I have done this a bunch of times on cars and boat trailers and never have had any adhesion problems, if you clean the surface well before starting to apply primer.




Don

 

I used two bottles of this with water enough to cover the parts.



Before:



During:



After, rinsed with water and a kitchen sink type brush, then rinsed in plain water again:



After after:



It works really REALLY well. Especially on cast iron. I have been driving with the chromed exhaust manifolds for a year with no chipping or peeling of the chrome. Just the nice normal blues and golds from the heat. I used that rubbermaid tub full over and over again.

That's my firsthand personal experience with phosphoric acid.

Also, something that's not been discussed yet it the prep for POR15. They sell a prep you're supposed spray bottle on parts after heavy scale type rust removal and prior to applying POR. I suspect this is also phosphoric acid. Same results. Instructions say to let prep sit for 20 minutes then spray with water. Then comes the POR.

I did my frame with POR using their prep and instructions, and it's still holding up great a year later.

 

No one answerd this so I asked the makers of Rage gold filler what they thought and heres what they wrote back:


Thank you for contacting ITW Evercoat. Below is the response from our product manager. Thank you again for choosing ITW Evercoat products.

I would not recommend using any of our polyester products over a phosphoric acid metal conditioner. There are too many things that can go wrong to cause the product to fail. He would be better off sanding the rust pits until there is no rust left and priming with an epoxy primer or Super Build 4:1.

Thats pretty much the answer I expected from them. That way theyre not "liable" for any issues.
Oh well maybe ill try it someday, but not on this build.

Jeff

 

Are you kidding me?? No one answered this?? I sure did.

 

HAha, no, I kid you not

I was wondering about the filler directly over the acid and I guess I diddnt know what "master series was".
Plus, an answer right from the products maker is pry the best bet.


Sorry, jeff

 

the answer was there:

 

I skipped thru this thread but didn't see anything about welding after treating. Does anybody know if there is any dangerous fumes from either welding or leading after treatment?
Getting rusted metal clean enough to tig weld or lead is a challange and this looks promising.

 

I would lead over it, but not weld.

The result of the etch is an oxide layer, if rust (iron oxide) can contaminate a weld, I would expect the black oxide layer to do the same.

 

Are any of you familiar with the PPG pretreatment products? http://www.ppg.com/coatings/autooem/products/Pages/Pretreatment.aspx
Or would this be a similar scenario as the quote below;

With all of the information circling around with old and new technologies; it's really difficult to determine the best route to take for prepping metal. I stopped at the paint supply store today and realized that PPG DX metal treatment products should not be used on sandblasted parts. http://www.bapspaint.com/docs/psheets/PPG/Automotive/Deltron/P-226.pdf

 

The reason they say that about blasted metal is because they are afraid you will leave bits of the acid in pores that are created by blasting. Personally, I have used it whenever and on whatever. I wipe it well before it dries and have had no problems. And yes this is basically phosphoric acid with a tiny amount of detergent and packaged through PPG.

 

Thank you Don!

 

and in small amounts, it is in some things that we actually put in our mouths . . food types, today.

 

Has anyone else had problems with thoroughly rinsing these type of phosphoric acid treatments off with water like it often says in the instructions?

I always see these photos of beautiful clean dull grey steel with bluey purplish hues but I'll be damned if I can get a consistent result. Have used a variety of quality products, mixtures and techniques trying to stick to the instructions as close as possible but after rinsing and drying frequently have the steel developing a greeny yellow tint.

Am using products now that you can leave to dry or wipe off then clean with solvents but both have their down sides in certain situations and it's one of those things that really bugging me (plus solvents are expensive)

 

Washing it all off before it dries to a hard crust should leave a clean surface. If you let it get dry and hard it will sometimes require some abrasive work.

As for the coloring I've had the same outcomes. From a mostly grey tone to an almost irridite gold on different pieces (pics in post on previous page). I've always chalked it up to differences in the alloy mix of the metal. While I don't use a clock as my guide for the amount of time I leave it on to work, I always clean it before it dries/hardens. I only mention that because I don't think that length of time affects the finish color.

 

God I have posted this info so many times for years and years on forums . . but here goes again. When I first started using phosphoric acid, it was a DuPont product. It said to wipe it off before it had a chance to dry. It worked perfectly. Many years later, I found that they ( DuPont ) had changed the direction to a water rinse. Many had complained of a flash rust after a water rinse. I always did it the way I first learned to do it. When I realized they changed their directions, I called DuPont. I spoke to a tech in the chemical dept who had first hand knowledge. he told me that people where allowing it to dry, which you clearly where not to do. I told him I had been wiping it off and wasn't interested in rinsing it, it worked fine. He agreed and said when he uses it he wiped it off as well and did not rinse. It was a change in the directions to cover theirs rears because people could not follow the original directions. This call was made some 20 years ago and I have been wiping it off only. So . which will you do? I am set with how I use the chemical. Trust me.

Now I keep some acid in a closed container that I dump bolts and things in to get blackened or just remove the rust. I may leave them in for a few days. That is totally different. When I remove them I let them dry, because the coating is what I want.

 

It is good to see that this stuff is being used. I think everyone on here makes valid points on how to use it. The way I use it may not be the same way others do, but as long as the end result is clean metal that's all that counts.

 

Good thread! I TOO have used several Phosphoric Acid based products. OSPHO, The Must for Rust (by Krud Kutter), Naval Jelly, and several others. They are all basically the same ingredients (with various concentrations), and are ALL toxic and should be treated as such, as others have mentioned. I've used these products with plenty of success. The important thing to remember is, use it for removing the rust, but if you're going to paint the surface, still do all the metal prep you would normally do, had you not known it was stripped with P.A.. Etch, lacquer thinner, whatever your recipe: clean the metal as if you would in any other situation. I also agree with those who have said "check your paint spec sheets". ALWAYS ALWAYS do that.

Welding. Sucks! You have to neutralize it one way or another. Your weld will be crap, otherwise.

I actually used Phosphoric Based cleaners recently on the inside of my Model A. It had been previously media stripped, but sat for awhile and begin to have surface rust in some places. I reduced some Phosphoric Acid with water, in a spray bottle, and went to town. I found that not letting it have a chance to dry helps (sometimes) for getting the heavy stuff knocked down. After the process was complete I prepped for paint like normal, shot with epoxy primer, and then sprayed my Lizard Skin right over it.

For smaller parts, I'll put it in a 5 gallon bucket and just let the parts sit for several hours. Pull the part(s) out, and rinse. Flash rust is likely after rinsing well, so I'll immediately coat it with something like Gibbs, oil, WD40, something, anything.

I've also tried several "Green" solutions for getting rid of rust. I've not been impressed with any of them. They work, but are generally not as cost effective, and tend to take longer.

I'll continue to use Phosphoric Acid, and will do so in a safe manner. I always ware a respirator, safety glasses, and the right type of rubber gloves. I have breathed this stuff in AND had it in my eye. The worst things that could ever happen. Accidents happen, and you don't want it to happen with this stuff! Take my advice!

 

Same with me, used Phosphoric acid from SW, soaked the metal, wiped off excess, never a problem. ALWAYS had a big ass fan blowing the fumes out the door, glasses and gloves.

 

I second what a MP&C said.I primered my 62 galaxie with HOK KP2cf after doing the exact same PA treatment.The primer came off in sheets.You MUST CLEAN it off!

 

great thread sorry I missed those pics Bob although they're a little more extreme than what I've experienced that's exactly the kind of coloring I was frequently getting.

Based on all the tech sheets I've read and responses here think I'll stick with the wipe off method, something about pouring water all over my freshly prepped bare steel panels really bugs me anyway.

 

Since rust is a chemical reaction, it is best to treat it with chemicals (metal prep). Don't know about today,but when in the 60's, i worked for GM car bodies were dipped in acid bath before paint and primer. Blasting has it own problems. Workhardening the metal is one. And although blasting does not get into small areas to remove rust,it does concentrate in seams,etc. and will be appearing for a longtime after.

 

My 34 after using a product called "phix"...phosphorous acid. And it's true...welding is a bitch after using this product.