chevman wrote:
When trying to remove stubborn rust, it helps a lot to blast it first, then use phosphoric acid to do the last of it.

Scott, I wrote this for others because I know that you probably only use acid for etching, and I agree with what you said, if using it only for etching.
You are probably also correct about Timmm's definition of surface rust.

Actually, I do not use P. acid for etching, but I have used it for rust removal.
After a panel is lightly tickled with sand, I DA it with 80, use P. acid until all the rust is gone, neutralize it and then shoot epoxy. Metal that has been blasted free of rust needs no acid treatment, just go straight to epoxy. I don't use acid for etching virgin metal either, I shoot epoxy. For restorations with a large amount of rust I send them out to a commercial media blaster and can't be bothered wasting time. They come back 100% free of rust.

Here is a good rust removal example for those of you who like elbow grease, scroll down: http://metalmeet.com/forum/showthread.php?t=4366

Randy is a great guy, very knowledgeable, and its obvious that he is very good with his hands, and I wouldn't limit that to just metal work. But he did that a long time ago, and I'm sure he would do it different today.

Navel jelly was more popular in years past, but now people have found out about better solutions of phosphoric acid. Navel jelly has 10-30% P-acid, I don't know why they can't lock it down exactly, most of the other brands seem to be able to offer a consistent mixture, Ospho for instance is 45%

Adding water to keep the acid wet dilutes it even more, but with a liquid version of P-acid, you can mist it without diluted. It works by dissolving the rust, so a SS wire brush or scuff pad will certainly speed things up.

I prefer to apply it with either a paint brush. Misting it on puts too much in the air for my liking.
Ospho is the brand I use since it is available at most hardware stores. 45% phosphoric acid.

Randy's thread was just an example of removal results, I never stated I used Naval Jelly. It is common sense to use a P. acid product that has a higher content. Klean Strip Prep & Etch is 45%, SEM has their own version.

Scott, I doubt any of us thought that Naval Jelly would be something you would use after trying it, certainly not with your experience and the products available to us today. We have seen the kind of work you do, and that speaks volumes.That link you posted is a good example of what can be done with phosphoric acid, although there are some other out dated things mentioned. And I just wanted to point them out.

Steel wool for instance shouldn't be used because the acid will dissolve it. A course scotch pad will also degrade, but will last a lot longer than steel wool, and works very well on the surface, but for rust pits, a stainless steel wire brush will last until it wears out. A big brush skims over the pits, so it takes one that looks more like a tooth brush to get into the pits and the stiffer the brush the better.

Naval Jelly was successful because the rust in that link was only mild surface rust, but the same results can be seen on pitted rust with a stronger solution such as Ospho---given some time, and (as mentioned) elbow grease. Coronet is right about misting, you will need a respirator and face shield to mist it.

Sometimes a non structural panel or brace might be saved using phosphoric acid, or you might even be able to avoid cutting out the rust areas, depending on how severe it is.

Removing rust in this way is time consuming, but it also requires time to cut and replace a brace for instance, time to get the right length, to line it up and get the right angle (front to back, side to side) in order to maintain the proper shape of the panel it is bracing. I like to make the decision on how to proceed after blasting.

timmm wrote:QUESTION: Should i attempt to remove the white "glaze" with the above mentioned products(w&G/sandpaper/isopropyl) prior to applying body filler, OR should i just apply the body filler over the rust treated areas?

tom

The best way to remove that white stuff is to rewet with phosphoric acid to reactivate it. Then if all the rust is gone, and you want to just protect the metal for up to a year or more while working on it inside the shop, just wipe the acid off while its thoroughly wet, and let it dry.

But if you are ready to apply epoxy, then you should rewet and scrub the area vigorously with a red scotch pad and brush the rust pits to make sure all the rust is off while keeping the whole area wet with acid.
And just before rinsing, rewet it very good and scrub with the scotch pad, this will help you to remove all the white and black residue with a rinse because once it just starts to dry, it won't all rinse off.

Before the rinse water dries I wash the metal with Zep purple industrial cleaner in hot water, rinse that off, then dry with clean towels.

Zep isn't just being used to clean, but mostly to help prevent flash rust. Dawn would be fine for cleaning this, but you will use zep for a lot of other things because it cleans grease at least 10 times better than Dawn, and zep has the extra benefit with flash rust.


http://www.zepcommercial.com/product/In ... oncentrate


http://www.homedepot.com/p/ZEP-128-oz-I ... /100047759

I've used steel wool and p. acid did not dissolve it.

ScottB wrote:I've used steel wool and p. acid did not dissolve it.

It just depends on how long its exposed to the Phosphoric acid, you probably didn't have the steel wool in there long enough.
P-acid etches metal by dissolving it, and true steel wool is steel. It may have a rust proof coating, but the acid will probably dissolve that also. What I have used didn't last long at all. I wouldn't use a kitchen type wool pad with soap in it, that might neutralize the acid, although copper and stainless steel is ok, without anything mixed with it.

No, I did not have the coarser steel wool saturated long enough to dissolve it, why would or could I? This is not complicated. Urinate on metal long enough and it will eventually dissolve. Pick your acid. Sub out your labor intensive processes and have cars blasted to save time for all your restoration jobs. If you have a commercial blasting system then you are better off yet.

hey guys,


thanks for all of the info, comments and link, i will be sure to reread them and possibly print them out before attempting the job.

hows this plan sound :

1) sand the surface rust/treated areas with 80grit
2) REACTIVATE the treated areas with phosphoric acid and steel wool, and try and remove as much rust as possible from the pitted areas. when i finally get everything nice and shiny, proceed to wash the treated areas with dish soap and plenty of water.
3) dry the treated areas with blow drier
4) apply primer
5) fill pitted areas with body filler/glaze

does this sound OK?

Since im in Europe, the red scotchbrite pads are out of the question.

one more question regarding the Primer:
the local paint-supplies-guy sold me an Acrylic primer, should i use it? or is an epoxy-based primer a must?



"I might be able to obtain the following: HEMPEL'S LIGHT PRIMER 45551
DESCRIPTION: A two-component polyamide adduct cured epoxy high build paint."

EDIT: I called to ask about the above mentioned HEMPEL epoxy primer, and was told that it is mainly used in boat applications. will take a look around tomorrow to see if i cAn find something more appropriate.



any further comments/suggestions would be much appreciated.

a big thanks to: 68 Coronet, chevman and scottB for your suggestions

tom

I'm not familiar with all of the tools available in Europe, but I would think a red Scotch-Brite pad is pretty commonly available at hardware and paint stores... Is it not? It is a pretty basic requirement for most types of paint prep.
It might be called a "scouring pad"....

The rest of the procedure sounds fine. The main goal is to clean and remove the acid residue while it is still wet.
A good cleaning with a scotch-brite pad, steel wool, or even a dish scrubber will work well to help agitate the rust and acid.

The soap and water will help neutralize the acid, since most dish soaps are a base.