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topic 5959

Questions in Prepping with Skyco Ospho rust converter

An ongoing discussion from 2000 through 2015 . . .


Q. My mother had a cattle corral built with oil field pipe which has a rusty look. It is not rust flakes. She has applied some of the Skyco Ospho [linked by editor to product info at Amazon] and it turned white. The instructions say you can wipe it off. This does not seem to be wiping off. Will this cause a problem or will it bleed through her paint if she paints over it?

Thanks for any response that would help her.

Martha Toler
- Victoria, Texas

A. Hi, Martha. The instructions don't quite say you can wipe off the powder; they say that you should brush off any loose powder. I suspect that the fence was maybe Ospho'd and left unpainted longer than overnight, so that more powder developed than usual, but I'd just get it painted. Good luck!


pic of Ted Mooney
Ted Mooney, P.E. RET
Pine Beach, New Jersey
Striving to live "Aloha"

To minimize your searching efforts and to offer multiple viewpoints, we've combined some threads into the dialog you're viewing. Please forgive any resultant repetition or failures of chronological order.

Cleaning concrete and tile surfaces stained by Ospho

September 15, 2008

Q. I recently used the Skybryte Ospho product to prepare wrought iron railings for refinishing. Small amounts of overspray, which contains phosphoric acid, contacted concrete and non-ceramic tile surfaces adjacent the railings, causing white spots to appear and reappear, even after scrubbing with a wire brush. What product would work to remove these spots?

Henry Mason
owner home renovation business - Virginia Beach, Virginia

November 7, 2009

A. Hi, Henry. I'd try letting a solution of sodium bicarbonate (baking soda [linked by editor to product info at Amazon]) and water sit on it for a couple of hours. Maybe made-up at one small box in a couple of gallons of water.

Baking soda is safe and should neutralize the residual mild acid that seems to be absorbed into the pores and is attacking the concrete and tile.


pic of Ted Mooney
Ted Mooney, P.E. RET
Pine Beach, New Jersey
Striving to live "Aloha"


Q. I have used ospho in my welding shop for a long time. We are looking for a anti-rust product to use on b-7 carbon steel bolts between flanges. We are not able to break these flanges and clean the bolts. We would like to possibly use the Ospho in a spray to coat these bolts. I also need a MSDS sheet.


"No-Ox-Id" Compound

March 20, 2009

A. Hi, Freddie. I don't think that's really what Ospho is for -- it's meant as a pretreatment for paint. You might be better off with an anti-oxidation compound like Sanchem's No-Ox-Id.

You should get a current MSDS from the manufacturer; one of our kind readers included part of the MSDS and references to where to get it in a response to letter 24030.


pic of Ted Mooney
Ted Mooney, P.E. RET
Pine Beach, New Jersey
Striving to live "Aloha"

Ospho Rust Converter

May 4, 2009

Q. Hi, I have used OSPHO for a long time to stop the rust and as a primer, a co. I worked for used OSPHO so that's how I got into using it.

I have a chain-link fence that has turned to rust in areas, it was galvanized at one time, would OSPHO work to kill the rust so I can paint it? And what kind of paint would you use?
And where do I get some more of the OSPHO, every one has got into my stash and I am about out. The fence I need to do is 900 feet long, how much do I need?

Wayne Moser
- Troy Montana

October 11, 2009

Q. I have a 2008 Jeep Wrangler and it has an area of pitted rust and Chrysler states that it is normal. I now have to take care of it on my own. Is Ospho the best product to use and what is the best way to take care of it.


David Sykes
Insurance - Mulberry, Florida

October 12, 2009

A. Hi, David. I think Ospho is usually the best type of product for this situation; we hesitate to pick one brand of rust converter over another though. The general idea is that you are trying to use a phosphoric acid based rust converter to convert this porous and dusty red rust into the more stable black rust.

If the area is easily accessible and the operation is practical, I'd actually say that sandblasting is actually better, but usually that's not practical. Good luck.


pic of Ted Mooney
Ted Mooney, P.E. RET
Pine Beach, New Jersey
Striving to live "Aloha"

November 18, 2009

Q. I hired a handyman (who said he had used Ospho before) to paint my wrought iron railing which had started to rust. He did not let the Ospho dry overnight before painting it black and now there is a white powdery surface on the black paint. What can I do at this point? I would appreciate any advice.

Karen Bennett
- Mill Valley, California

July 16, 2014

Q. Do I have to let this stuff dry completely before I apply finish paint?

Angel Pagan
- Wrightsville Pennsylvania USA

July 2014

A. Hi Angel. If by "this stuff" we are still talking about Skyco Ospho, their instructions say to allow to dry overnight, and they give a phone number to call for clarifications. Good luck.


pic of Ted Mooney
Ted Mooney, P.E. RET
Pine Beach, New Jersey
Striving to live "Aloha"

August 23, 2015

Q. How do you get it off concrete?

- BURNET Texas usa

August 2015

A. Hi. I'm not sure what you mean by "get it off". You should be able to just rinse it away. The Ospho directions say: "Avoid getting OSPHO on adjacent areas such as painted surfaces, concrete, masonry and stonework. If splashing occurs, flush immediately with water to remove.".

It is acid and will attack concrete if left there for any time. And you can't undo any attack that it has done; you would have to repair the concrete.


pic of Ted Mooney
Ted Mooney, P.E. RET
Pine Beach, New Jersey
Striving to live "Aloha"

February 12, 2017

Q. I am restoring an old bakers rack. It is made of wrought iron, with brass trim. The brass trim pieces do not come off, and I need to treat the iron for rust. I have used OSPHO on other projects before, with good success, however, I can't find any information on how it affects non ferrous metals. Will it mar or etch the brass?

Patrick Cooke
- Orlando, Florida, USA

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