Ospho removal

C

carolinacustoms

Ok guys, I need some advice from those who use Ospho and know how to successfully remove it prior to applying epoxy primer to avoid adhesion problems. I am supposed to start a project in the next few weeks that has been acid dipped. It is all bare metal that the dipping company coats with Ospho for rust protection until primer is applied. I have never dealt with ospho and understand that if it is not removed properly it will cause a world of problems later. I have read where some say to re-wet the area with Ospho and rinse it off, then clean with W&G and it is good to prime, however I would like to hear it from some that are actually using the product successfully and not having problems. What about all of the cracks between braces and around the panel skins etc? Will it leech out later and cause problems? This is a high profile vehicle that will be featured in several magazines and will possibly be the cover for one of those. It will be shown nationally and I definitely don't need to have any de-lamination problems arising. The customer has already had everything dipped, so I unfortunately cannot try to talk him out of the process. I will be using SPI products from beginning to end if that makes the process any different . Any help and advice is appreciated.

Kelly
 
The way you described is the way I understand it. The acid dip would be a major concern for me though.
 
unless i knew the company that dipped it i would run backwards.unless it was dipped rinsed and ecoated i would pass.there is acid in places i doubt you will ever get rid of it. also depends on what it was dipped in.
 
If it were me, Jambs inside fenders I would clean with a light sand basting.
Oust side panels, I would wipe with ospho, let set a few minutes and rinse off.
Then Da outside panels with and 80 DA and wash with 700 and epoxy.
 
Thanks for the advice guys, I will try to find out exactly what they are using. The guy has a few other show trucks that have been done this way, and they have been finished for several years with no problems so far, but I have never dealt with anything that was dipped and ospho coated, so I didn't want to make a huge mess.

Kelly
 
Here is a write up on the companies website. From what I can gather, they only coat the car in ospho once it is dipped and then cleaned/neutralized to prevent flash rusting. I plan to call them tomorrow just to get the exact information, but if they are washing, rinsing, and neutralizing all acids, then just coating with ospho, it should be as simple as re wet and then rinse off, SPI 700, DA80 grit, then 700 again, and epoxy correct?


"Using our temperature controlled oven, Carolina Chem-Strip was able to remove all seam sealers, undercoating, and bondo from the car before placing the Mustang into an acid bath for complete chemical stripping. The acid bath eliminated all scale and rust.
Next we washed and dried the automobile. Then the Mustang was chemically stripped, we then neutralized the vehicle in a high alkaline tank and applied an Ospho coating to preserve the car’s steel exterior and prevent against further rusting. With the ability to restore any part, big or small, we were able to chemically strip the full body of a 1968 Mustang."
 
Rather than start a new thread I'll just piggyback on this one.

I need to reactivate the phosphoric acid treatment I put on my car. I used Eastwood After Blast rather than Ospho.
- Does anyone know the concentration strength of Ospho and Klean-Strip Prep & Etch?
- I already have an unopened gallon of Klean-Strip. Should I return it and use Ospho to reactivate and then follow the procedure to neutralize the Ospho?

The Klean-Strip is cheaper than Ospho but I won't use it if it is not recommended here by the experts.

Thanks,
Emil
 
Hope this helps,
Looking at the Safety Data Sheets the Klean-Strip Prep & Etch shows Phosphoric acid {Orthophosphoric acid} 35.0 -45.0 %. Specific percentage of composition is being withheld as a trade secret.
The Ospho shows Orthophosphoric Acid, 45% by weight.
The Eastwood After Blast is listed at 5-25% Phosphoric acid

I guess the question would be what makes up the other 55+%. Barry states in the manual that Ospho is the only one he recommends. If it was me and I could return the Klean-Strip, I would, and go with the Ospho.
 
Last edited:
Water is what makes up the majority of the rest. The active ingredient is the phosphoric acid.

I don't think you need to return it. Short of returning it, you can wet it with the product, keep it wet for at least 15-30 minutes, if you have some scotchbrite pads scrub the surface while wet with one. (use gloves). After you have re-wet the surface and kept it wet for at least 15 minutes you can then rinse it with water. It will flash rust some, this is normal. As long as you re-wet it and keep it wet for a long enough time you will be OK irregardless of what you use.
 
Thank you both for the advice. I must be challenged when it comes to reading the SDSs because I went top to bottom and completely missed the percentages. I was already leaning towards Ospho since it is what Barry recommends so Ospho it is (it's cheaper than having to redo the epoxy). If I can't return the KS I can always use it to remove uratic salts from the toilet and hard water film from the shower glass.

@Chris_Hamilton
- Should I rinse with water alone or water followed by a water/Dawn solution and a post rinse?
- I have both RED and BROWN Scotch-Brite pads. Which would you recommend?
- The bare metal was sanded with 80 grit AFTER the phosphoric treatment was applied. Do I need to re-sand after the neutralizing and scrubbing with Scotch-Brite?

-----
Emil

 
Fiz I just use a maroon scotchbrite because that is usually what I have on hand. Use the coarsest one you have. I just rinse with water. No experience using dawn solution. Wouldn't hurt anything to do it that way. If the flash rust is heavier than I like I will DA it with 80.
 
The bare metal was sanded with 80 grit AFTER the phosphoric treatment was applied. Do I need to re-sand after the neutralizing and scrubbing with Scotch-Brite?
Phosphoric acid etches metal at a slow rate.

1652954710885.png


Thin metal or sharp edges will be eaten the quickest, which means acid will have a smoothing effect on your previous 80 grit DA scratch. To prove this point, just drop a freshly blasted part in a container of phosphoric acid and watch it fiz. So for maximum adhesion you need to do the 80 grit scratch after any acid treatment. That will also provide some assurance that all the acid is gone.
 
Phosphoric acid etches metal at a slow rate.

Thin metal or sharp edges will be eaten the quickest, which means acid will have a smoothing effect on your previous 80 grit DA scratch...
That was my understanding. Thanks for confirming that I need to redo all my work. Learning can be hard :(

-----
Emil
 
ospho or milkstone . either will super clean the metal and get the old coating off. i would do it twice sine no telling what they used .
 
Anybody know what affect Ospho, and the water to rinse it would have on filler that was applied direct to metal. Long project has developed a lot of surface rust. Generally short strand fiberglass over welds and filler over that.
 
Anybody know what affect Ospho, and the water to rinse it would have on filler that was applied direct to metal. Long project has developed a lot of surface rust. Generally short strand fiberglass over welds and filler over that.
Filler needs to be removed that was applied direct to metal!!! Epoxy over metal, then your body work..Newbie here, but those are the facts from the pros
 
Back
Top