How to neutralize Ospho

When the intention is to leave ospho on the panel for protection, it still has to be wiped off with a dry rag, leaving only a thin film.
This would be in the case of protecting the bare metal during the body working process, and when ready for paint then it should be rewet with a scotch pad and rinsed off completely.

So In the body work process, spot welding and maybe grinding, fall under the same principle as when Barry said, "sandblasting takes care of everything."? In other words, the acid coat would be vaporized etc. with welding and grinding?
 
So In the body work process, spot welding and maybe grinding, fall under the same principle as when Barry said, "sandblasting takes care of everything."? In other words, the acid coat would be vaporized etc. with welding and grinding?

No, because metal has pores. You can remove it partially by sanding but sanding can't reach the microscopic pores.
 
The ONLY acid cleaners SPI recommends is Opsho, PPG and DuPont metal preps as long as their instructions are followed to a tee.
Use any other system you want, just do us a favor and use no SPI over them.

There can be NO shortcuts for good results.


Ospho, is a great product for automotive if used right, we give scare warnings because we want people to call so we can make sure they know how to neutralize it, so no problems will arise.
Only one way to use and here it is:

Use as needed and apply as many times as needed to get the spot clean, let dry and leave for months if you want, don’t matter.
To neutralize the Ospho MUST be wet, so if dry, re-wet with itself and let set one or two minutes and with a clean rag and water, wipe off like washing the car and then dry.
Next, then da car with 80 grit, clean with 700-1 wax and grease remover, let set an hour and coat with an epoxy.

Notes of interest (maybe)
If you try and sand dry film off you will lose 40-60% adhesion (per adhesion tester as some will embed itself in metal and amount depends on how long the Ospho has been on panel as we do know acid films degrade with time but due to many factors we cannot pinpoint a time frame.
The tape is not a test, use razor scraper after 7 days or an adhesion tester if you have an extra $6000 to spend.
How does it fail? Here are a few calls.
Washing car and hose bounced up, hit car and paint bubbled.
Kids finished ball game and ran by car and tossed ball gloves on hood, next day two big bubbles.
Wife got bag out of trunk, closed trunk and set bag on truck to play with keys, next day a bubble there.

My FAVORITE TECH CALL at least once a month, my body filler dried and sanded great but when I got to metal is was gummy, DO I HAVE A BAD HARDENER? Nope only one thing, you applied it over an acid film.

The ONLY acid cleaners SPI recommends is Opsho, PPG and DuPont metal preps as long as their instructions are followed to a tee.
Use any other system you want, just do us a favor and use no SPI over them.

There can be NO shortcuts for good results.


Ospho, is a great product for automotive if used right, we give scare warnings because we want people to call so we can make sure they know how to neutralize it, so no problems will arise.
Only one way to use and here it is:

Use as needed and apply as many times as needed to get the spot clean, let dry and leave for months if you want, don’t matter.
To neutralize the Ospho MUST be wet, so if dry, re-wet with itself and let set one or two minutes and with a clean rag and water, wipe off like washing the car and then dry.
Next, then da car with 80 grit, clean with 700-1 wax and grease remover, let set an hour and coat with an epoxy.

Notes of interest (maybe)
If you try and sand dry film off you will lose 40-60% adhesion (per adhesion tester as some will embed itself in metal and amount depends on how long the Ospho has been on panel as we do know acid films degrade with time but due to many factors we cannot pinpoint a time frame.
The tape is not a test, use razor scraper after 7 days or an adhesion tester if you have an extra $6000 to spend.
How does it fail? Here are a few calls.
Washing car and hose bounced up, hit car and paint bubbled.
Kids finished ball game and ran by car and tossed ball gloves on hood, next day two big bubbles.
Wife got bag out of trunk, closed trunk and set bag on truck to play with keys, next day a bubble there.

My FAVORITE TECH CALL at least once a month, my body filler dried and sanded great but when I got to metal is was gummy, DO I HAVE A BAD HARDENER? Nope only one thing, you applied it over an acid film..
About 40 years ago I had some rust and pin holes in a small area in my floor boards. I used a product called Rust-Pho. Probably some type of phosphoric acid because it turned the rust black and white powder. Let it dry and then bondo over. Floor is still solid 40 years later. Anyone ever hear of Rust-Pho or used it?
 
I'd use molasses especially for small parts. Usually 1:9 ratio molasses to water. Pure molasses if in a hurry - overnight to a couple of days.

*I have a bare metal panel in the basement since November. It won't rust this time of year because humidity is 45% and under. No dehumidifier required.
 
Did anyone read the first post on this thread? Barry knows the chemical game inside and out as well as what will work on stuff he created. I have called him before when I used ospho on something in the past to make sure I did everything right. Hope this helps.

Also not all epoxies are the same. SPI epoxy isnt made to go over an acid film.
 
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And then there is this: Evapo-rust
Has anyone info or experience using Evapo-rust for rust removal, then Epoxy Prime on small parts. I'm considering trying it for de-rusting parts that are too small for blasting and wire wheel.
Based on data sheet it is neutral ph 6.0 vs acid (Ospho is acidic at ~1.6 ph)
Website: https://www.evapo-rust.com/evapo-rust-faqs/ data sheet:
Neutral pH is 7.0. Looking at the data sheet you linked to the pH of the product is 5.9. That makes it slightly acidic. It also showed that it is up to 90% water. My guess is that it is similar to Ospho and uses phosphoric acid, but is much weaker thereby requiring longer to work. Irregardless it is still slightly acidic and therefore would leave an acidic film if not neutralized.

Molasses pH is in the mid 5's. Similar to this stuff.

Molasses, evapo-rust, rat piss, it doesn't matter. If it is acidic it needs to be neutralized if you plan to use SPI Epoxy over it. End of story. Any other questions refer to the first post.:)
 
Back when I painted at a high end resto shop they had all kinds of paint issues. When I started I gathered all of the tech sheets they had and started reading through everything. I found I stack of problems with the process the previous painter was doing. But for the life of me I couldn't figure out why the paint was bubbling on a lot of cars. I kept it in the back of my head, but one day I noticed the shop helper walking around and wiping all the bare metal cars down with a ppg metal prep. He would just dip a scotch bright pad in a cup full of this stuff, scrub the panel and then wiped it dry with a towel. I didn't even know this stuff was in the shop.
 
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Next question. Is there an Epoxy Primer that is compatible with acid residue from metal prep solutions?
 
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