How to neutralize Ospho

reallylongnickname

Promoted Users
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?
 

Chris_Hamilton

Trying to be the best me, I can be
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.
 

DougT

New Member
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?
 

Chris_Hamilton

Trying to be the best me, I can be
Epoxy won't adhere to a acid film. That's why you have to neutralize it. Always the correct thing to do whenever you use a phosphoric acid wash.
 
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