[abefromen]

After stripping my '73 Firebird here is what I found. The car sat outside for a long time and has developed surface rust under the paint. Whats the best way to remove this and treat the metal before I spray the DP90?

[abefromen]

Here is the 1/4 panel......

[GStage1]

Go to Home Depot and get a gallon of phosphoric acid....green liquid in a translucent bottle. Use a brush to apply it and let it sit overnight...it will chemically neutralize the rust. Wipe off any white residue with acetone or lacquer thinner. Prepare the panel for paint like a new metal panel.

[carcrazy]

As noted, Phosphoric acid will take care of it. Home Depot (Must for Rust) or Lowes (Jasco) will generally carry it in the paint departments. Any automotive paint jobber will also carry it but it will probably be more expensive. Another real good product is Pickelex. It is also Phosphoric acid based and is available at autobodystore.com

[69gp400]

will navel jelly do the same? i have the same problem on my 39 buick and someone said the jelly is good.

[Greg Reid]

Originally Posted by 69gp400

will navel jelly do the same? i have the same problem on my 39 buick and someone said the jelly is good.

That's old technology and slow as Christmas. That phosphoric acid will do the trick much more efficiently in my opinion.

[Greg Reid]

Originally Posted by GStage1

Go to Home Depot and get a gallon of phosphoric acid....green liquid in a translucent bottle. Use a brush to apply it and let it sit overnight...it will chemically neutralize the rust. Wipe off any white residue with acetone or lacquer thinner. Prepare the panel for paint like a new metal panel.

From reading this, you seem to imply that it's not necessary to actually remove the rust, just wipe the white coating off and paint?
I've used this product before but I kept wirebrushing until I no longer saw any rust. Is that not necessary?

[PONTIAC SLEEPER]

PPG also Has a pospheric acid product wich is similar to what you can get at home depot But seem to be stronger and more concentrated. PPG DX579 Just make sure you neutrlize These types of acid coatings before applying The DP90 Or you will have major issues!!! If you Use water it will flash rust... I always use red scotch brite and Acetone with the proper Safety equipment. The acid will give you a chemical burn if you are not care full...

Copied this from http://www.tcpglobal.com/autobodydepot/rustremove.aspx

"DX579 is a multi-purpose phosphoric acid based cleaner and prepaint conditioner for most metals. It can be used to deep clean a metal surface prior to paint or to prepare a surface for a subsequent chemical coating. PPG DX579 is blue in color and could lighten over time."
It was like $11 for a Quart and $30 for a gallon last time I bought it locally. Was having a hard time getting it Here because of the strict regulations but I found a shop that had no problem getting it so I just order a Case of it and split it with freinds whom always wanted to borrow mine...

[69lm69gp]

I have had good luck with Must for Rust on light rust. I also just tried a product called Rust Bomb it is made by the same company that makes Evaporust but it's a gel so you use it on things that are too big to soak in Evaporust. If anyone is interested I can post pics of a test area I did on my car when I get home tonight.

Also read this:

http://www.hotrodders.com/forum/secr...led-55679.html

[Greg Reid]

Again....Do you guys try to remove all traces of the rust when you use these products...(that's what I did) or is it only necessary to treat it and wipe the neutralized rust down?

[carcrazy]

Greg,
I apply, let it sit, then wipe it off, I continue this process until it is gone. ( I use a white cloth and continue until the cloth looks clean after wiping) If an area is a real pia I will apply with scotch pad, hit with sandpaper, etc and repeat. I don't want to see ANY rust! I do not use water as it will cause flash rust very quickly!

[PONTIAC SLEEPER]

Originally Posted by carcrazy

Greg,
I apply, let it sit, then wipe it off, I continue this process until it is gone. ( I use a white cloth and continue until the cloth looks clean after wiping) If an area is a real pia I will apply with scotch pad, hit with sandpaper, etc and repeat. I don't want to see ANY rust! I do not use water as it will cause flash rust very quickly!

Basicaly use this process... If the rust is heavy or really hard to removethen you may need remove by sanding... It it is pitted, I would recomend a blasting process. Its really the only way to get down into the affected area....

[JDHolmes]

Personally, I'd grind it all off, wipe it down then paint it. I might toss in some phosphoric after the grinding, but you're going to have to get the loose stuff off anyway so you might as well remove the rust as it should be rather than just treating it. Without removing the treated rust, it will show through you paint.

[Greg Reid]

Ok, thanks guys. That's what I was wanting to clarify.
It's pretty much the way I was using the product but one of the previous postings made me wonder if it was just a matter of neutralizing it chemically then painting over it.
Just wanted to make sure I wasn't missing something there.

[PONTIAC SLEEPER]

Originally Posted by Greg Reid

Ok, thanks guys. That's what I was wanting to clarify.
It's pretty much the way I was using the product but one of the previous postings made me wonder if it was just a matter of neutralizing it chemically then painting over it.
Just wanted to make sure I wasn't missing something there.

As much as there is stuff saying that its Neutrilized I like to see bare metal when the process is done... As far as the term grinding Goes that term always makes me think about it on the aggresive side. If you do any type of grinding Just becareful you dont get caried away. Always finish off any type of grinding with like 80 grit on the DA. Deep scratches in the metal can also show up in a Paint job When The material Expand and contract in different Climates

[MetalHead175]

Can't you smooth it out and throw a skim coat of body filler on it to make sure those scratches don't show through? That's what I've done...not alot, but just enough

[mike nixon]

Originally Posted by MetalHead175

Can't you smooth it out and throw a skim coat of body filler on it to make sure those scratches don't show through? That's what I've done...not alot, but just enough

you can use filler. i prefer high build primer, i've had less shrinking issues with it.

mike

[65Mark]

The best way to remove surface rust, I feel, is with a soft pad on a grinder with 80 grit disks. I use an air grinder, not a heavy electric one. A light touch and keep it moving and the rust goes away in a hurry. The 80 grit will give it some "tooth" for primer to stick. Then I use a self etching epoxy , then high build primer. There are many ways to skin that cat, tis is my way. I have no faith in conversion coatings so I never use them.

[PONTIAC SLEEPER]

Originally Posted by 65Mark

The best way to remove surface rust, I feel, is with a soft pad on a grinder with 80 grit disks. I use an air grinder, not a heavy electric one. A light touch and keep it moving and the rust goes away in a hurry. The 80 grit will give it some "tooth" for primer to stick. Then I use a self etching epoxy , then high build primer. There are many ways to skin that cat, tis is my way. I have no faith in conversion coatings so I never use them.

soft pad on a grinders are a good idea too FWIW pospheric acid type products are not a conversion coating they actually break down light rust you just have to neaturalize them when your done... I use acetone and red scotch brite to clean the surface... the red scotch brite helps remove contamenates that a regular soft cloth won' catch. when thats done, I then go back with a soft lint free cloth and acetone untill the surface wipes up clean...
my worth

[65Mark]

I was referring to POR 15 on conversion coating, among others. Phosphoric acid is a good etch, as long as you neutralize it completely.