Phopherous Coating removal Do or Dont?

[72Charger72]

I just got my car back from acid dip and is has a phosphorous coating on it but apparently not that well as it has some minor surface rust forming. Mainly in areas that will be replaced anyway...rear quarters and floor pans.... I was reading about prepping for epoxy coating and there seems to be some controversy as to weather you need to remove this phosphorous coating or not before applying epoxy coating?
Just wondering what the experts on here recommend?
If removal is required I have read acetone wash then scott bright and 80 grit sanding. Can this be done in sections followed by expoy coating? There is so much garbage on the internet its hard to tell whos suggestions are the correct way to go about it?

[Pete in NH]

Hi,

Well, as usual the answer is it depends. You should  carefully follow the epoxy primer manufacturers instructions for their epoxy. I've used SPI epoxy and they do not want phosphorous coatings under their epoxy. Other manufacturers might be okay with it.

I've seen test videos for SPI epoxy over phosphorus compounds and it  greatly reduced the adhesion. So, I would get the tech. sheets for the epoxy you are going to use and see what they say or call the tech. support line for that epoxy.

Also, don't use acetone for a cleaner, use the epoxy makers recommended cleaning procedure. Acetone can leave unwanted residue behind. Today's paint materials are kind of high tech. and must be used exactly according to the manufacturer's to get the best results.

[green69rt]

I sprayed my bare metal with phosphoric acid/zinc phosphate solution to prevent rust after stripping my car.  The solution manufacturer (POR15 Metal Ready) recommended removing loose phosphate before painting.  Trouble is...how do you define loose!   When getting ready to prime, I just sanded everything down to a shiny finish with 150 grit paper.   I'm sure I took all or almost all the phosphate off so it was like painting bare metal.

I asked one of my lab buddies and he said the acid is the important part as it changes the top layer of the steel (it pickles it)  so anything setting on top of the metal has limited importance as far as protecting the metal.  I don't know if this is true but it sounds good to me.

[72Charger72]

Thanks guys...

I PM'd "Daytona R/T SE" he used the same guy to dip his car.
Also I have a call into the guy who dipped it trying to find out what kind of phosphate he used. Then I can contact
the Eastwood guys and verify things with them since IM using Eastwood epoxy primer. I bought some POR15 before I decided to acid dip so I may follow back up with a round of that.

I guess there are many different paths you can follow which is why I posted this.
Dont want to go backwards again if I need to take vacation and get this thing primed ASAP I WILL!  

[Pete in NH]

Eastwood epoxy used to be and maybe still is re-labeled Kirker epoxy. I looked over my Kirker product sheets and they don't say anything about applying it over phosphate coatings. I would try contacting Kirker directly as I doubt the Eastwood guys are going to know.

[72Charger72]

Eastwood epoxy used to be and maybe still is re-labeled Kirker epoxy. I looked over my Kirker product sheets and they don't say anything about applying it over phosphate coatings. I would try contacting Kirker directly as I doubt the Eastwood guys are going to know.

Thanks Pete....Just got off the phone with the dipper and the Eastwood guys were not familiar with the product the dipper used.
It is KO formula 119 www.komfg.com says it good for light rust removal and metal priming to prepare for paint. I have a call into them now.

Eastwood said not being familiar with the product they recommend sanding whole car with 180 grit and then washing with Eastwood Pre before spraying the epoxy. I can try Kirker to see if they know anymore but it looks like I am going to be in a rush to sand and prime the car before I lose the benefits of the dip.
The phosphate coat was supposed to give me a yr or so of grace time though all I needed was a few months. 

[72Charger72]

Thanks for the Kirker info Pete. They would not confirm or deny the rebranding but were willing to check out the product from KO and he is running it up to the lab to check things out. I Just heard back from him and he said you surely can epoxy coat over the phospherous...at least the KO Formula 119.  

[hemi-hampton]

Thanks for the Kirker info Pete. They would not confirm or deny the rebranding but were willing to check out the product from KO and he is running it up to the lab to check things out. I Just heard back from him and he said you surely can epoxy coat over the phospherous...at least the KO Formula 119.  

Did he say how to prep or prepare the Phospherous coating before you epoxy prime over it?  LEON.

[72Charger72]

Thanks for the Kirker info Pete. They would not confirm or deny the rebranding but were willing to check out the product from KO and he is running it up to the lab to check things out. I Just heard back from him and he said you surely can epoxy coat over the phospherous...at least the KO Formula 119.  

Did he say how to prep or prepare the Phospherous coating before you epoxy prime over it?  LEON.

He just said the guys in the lab said you could just epoxy coat right over it no prep involved?

[Pete in NH]

Thanks for the Kirker info Pete. They would not confirm or deny the rebranding but were willing to check out the product from KO and he is running it up to the lab to check things out. I Just heard back from him and he said you surely can epoxy coat over the phospherous...at least the KO Formula 119.  

Did he say how to prep or prepare the Phospherous coating before you epoxy prime over it?  LEON.

That advice is a little scary to me. The adhesion of the primer to the bare metal is the foundation of all the coatings that come after it. If the primer adhesion fails everything is going to come off.

SPI recommends the following procedure for metal that has been phosphorous coated- re-wet the surface with the same phosphorous coating and while it is still wet, flush with plenty of water. Then wipe it dry with clean rags. When dry, I would prep. the surface with the procedure that Kirker recommends for bare metal.

Re-wetting the surface with more of the same phosphorous product will dissolve the dry material left on the surface so it can be flushed off with water. I think I would do this one panel at a time to get the metal in epoxy primer as so as possible.

He just said the guys in the lab said you could just epoxy coat right over it no prep involved?

[72Charger72]

That advice is a little scary to me. The adhesion of the primer to the bare metal is the foundation of all the coatings that come after it. If the primer adhesion fails everything is going to come off.

SPI recommends the following procedure for metal that has been phosphorous coated- re-wet the surface with the same phosphorous coating and while it is still wet, flush with plenty of water. Then wipe it dry with clean rags. When dry, I would prep. the surface with the procedure that Kirker recommends for bare metal.

Re-wetting the surface with more of the same phosphorous product will dissolve the dry material left on the surface so it can be flushed off with water. I think I would do this one panel at a time to get the metal in epoxy primer as so as possible.

I dont have any of the product but I could see maybe wiping down with water again but what I have read about the phosphorus is it chemical reaction is triggered by water? Maybe using Pre or other cleaning prep would do but I am really confused by their spec sheet listed below?

To me it says it is a pre-paint prep? and the guy who dipped it said usually people he does this for just dip and then shoot the car? 

http://komfg.com/files/2011/12/119.pdf
Here is the info from the KO product sheet says it makes for better paint adhesion and bonding.
Metal Prep
TM
is a
ONE -STEP
acid cleaner, phosphate coater and light rust stripper.  It is used to
wipe down metal, remove light rust and heat treat scale and hard water lime.  It also gives a light
phosphate coating to metals prior to finishing for better paint adhesion and bonding.
>  Acts as a combination cleaner/coater.
>  Very Stable in hard water.
>  Increases the bond between metal and paint 

[Pete in NH]

I noted on the KO product sheet they talked about painting "industrial " type equipment and the like, not automotive paint systems. Industrial paints are not anything like modern automotive paint systems.

I used to use a similar PPG metal prep (DX-579) meant for automotive use under the old lacquer based primer systems. I think such acid/phosphate systems are useful in dealing with microscopic rust pitting. These chemicals convert iron oxide (rust) into a more stabile compound. I still think they have their place when dealing with rusty metal, even in newer automotive paint systems if properly neutralized before primer is applied.

The question here is what is "proper neutralization". I see leaving a thick coating of acid residue in places or sanding it into the metal surface as asking for trouble down the road. Epoxy primers are really great primers. When they fail it is usually because of improper surface prep. and cleaning.

You might want to take a look at the Southern Polyurethane Inc. (SPI) website and user forum. This is the only internet site I trust for automotive paint information. Unlike many other sites this one is where the professional guys to do restoration work hang out.

[72Charger72]

Thanks Pete I will check that site out. And I agree in the long run a little extra cleaning and prepping time could save the rest of the job later! 

[hemi-hampton]

I noticed the spec sheet had a whole list of Applications & did not mention Automotive. Does not surprise me.   LEON.