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How does Ospho compare to Gem Rust Killer and PickleX 20?

February 23, 2011, 10:04:50 pm

When checking out where to buy CorrosionX I came across the mention of Ospho.  As I had recently discovered that one of the newer 8D batteries I have has caused some rust to occur where the battery out gassed below the frame.  I thought I would compare the two products I have with Ospho by looking at their MSDS sheets.  It turns out that Ospho has 75% phosphoric acid versus 30 to 50% in Gem Rust Killer.  I was surprised to find that there was NO phosphoric acid in PickleX 20, as a matter of fact PickleX 20 does not even have an MSDS sheet. 

I came across PickleX 20 (PickleX apparently used be called Rass O'Nill) on some web site talking about auto frame restoration, it sounded good so I ordered some from the company.  At the time it seemed fairly expensive at $30.00 a gallon (now it is $139.80 per gallon!).  I used it on my race car after sandblasting it.  I found that it did work but it seemed somewhat gummy as it dried and sometimes left a raised dry film that would have to be sanded off. PickleX 20 did not seem to need cleaning on parts that were dirty.  While the product is claimed to be safe to handle it did eat holes in the concrete where it dripped and I did not see it.  It was not an immediate event but when I discovered it a week or so had passed.  I used gloves applying it but if I got some on my skin it did not seem to burn.

I then bought some Gem Rust Killer from a local auto body paint store and tried it.  It worked fine but sometimes it would take several applications to get the job done.  It did require that the item not have any grease or oil on it or otherwise it would just bead up.  I just bought a single spray bottle of it, probably a quart, and it was $17.00.

How does Ospho compare?  Does it require that the part be clean?  Does the higher phosphoric acid content help?  Where do you buy it?

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Re: How does Ospho compare to Gem Rust Killer and PickleX 20?

Reply #1 – February 23, 2011, 10:19:39 pm

John,

I have used Ospho on surfaces I am priming to paint.  It turns ferrus oxide (rust) to ferrus sulfate (inert salt), every molecule.  When dry, it is ready to paint.

I have cleaned the surface but have never had to have it pristine to have it work well.

The acid for the chemical reaction to turn rust to an inert salt and to etch the surface for better adhesion seems a good solution for priming metal surfaces for me.

I have found it at many hardware stores, Lowes and Home Depot.  It is a green watery liquid.

Hope this helps.

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Re: How does Ospho compare to Gem Rust Killer and PickleX 20?

Reply #2 – February 23, 2011, 11:53:04 pm

Rudy,

A minor point, according to the Ospho website it converts it to iron phosphate, not sulfate.  My chemistry is rusty (pun intended) but I could not see how H3PO4 could convert something to a sulfate.

I'll check both Lowe's and Home Depot which are fairly close by, thanks.

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Re: How does Ospho compare to Gem Rust Killer and PickleX 20?

Reply #3 – February 24, 2011, 12:16:36 am

I usta be able to keep my ous'es, ic's, and ate's straight... Been too long outa nuke power...

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Re: How does Ospho compare to Gem Rust Killer and PickleX 20?

Reply #4 – February 24, 2011, 10:30:28 am

John,

I suppose that if I was a really smart person I would have recognized the lack of sulfur in Ospho and the presence of phosphoric acid would yield the result you describe.

The devil is in the details.  Thanks for the kind input as I appreciate knowing the correct result.

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