What is the difference between Ospho and regular old phosphoric acid that you can get at the local hardware store? They are both basically just orthophosphoric acid.
http://ospho.com/images/OSPHO SDS COLOR 2019.pdf ORTHOPHOSPHORIC ACID 45% by weight. Compare to other brands.
OK, just checked Klean Strip phosphoric acid, and it says concentration is between 10 and 30 percent. Kind of a weird spread, but they say they don't show actual percentage because their formula is proprietary. Miracle Sealants Phosphoric Acid Cleaner says their stuff is between 25 and 50 percent
Did I say that? It was a pretty simple question. I merely asked what made Ospho different, you stated a percentage and said compare to other brands, so I reported what I found with other brands
I know the question is simple. You could probably formulate something very similar using various percentages of phosphoric acid. However I have used Ospho for years. It works out of the bottle as is and turns rust to iron phosphate which makes ferrous metals rust resistant and also provides a good surface to accept primer or paint. I will continue to purchase as is. Your mileage may vary!
I used to use DuPont Metal Prep. But now days I guess its called old painter out of touch with modern products junk. .. General prep you reduced it with water .
Usually, I would expect stronger is better. But not always. Gotta be a reason why nobody sells this stuff straight.
Ospho has worked right out of the bottle for me, for many years as well. As long as it keeps working, I'll keep using it. Generally, when I see a new product telling me it works "as good" or "better then" an older original product, that tells me the original was good stuff and they are trying to trick you into trying their product instead of the industry leader.
I think it just means the old stuff has been around for a while and has brand recognition. In some cases, like if you’re diluting it with water anyway, concentration doesn’t really matter. Just dilute it less, knowing that will take away part of the cost advantage of the bargain brand. I have an old bottle of the DuPont green (or is it blue) stuff that I have been rationing, but in the meantime I use a multitide of alternative products. I really can’t tell much, if any difference, but I feel better about using the DuPont stuff anyway, although in my heart I know I’m just being suckered by branding.
This may be more than you want to know or care about but probably answers the the OP’s original question. Many military contracts as well as civilian contracts require a chemical conversion of the surface prior to primer and paint with phosphoric acid sometimes referred to as an acid wash or prime wash. This is controlled by a Mil-Spec. Mil-C 10578D lists five different preparations of phosphoric acid for different applications. This Mil-Spec should provide actual components and how to prepare them. As with most Mil-Spec’s it will give you more information then you probably need or want. Mil-Spec are available on line and with enough looking you might find the spec for free. As far as what is actually in Ospho you might try looking up the Material Data Sheet (MDS) however I doubt it actually list ingredients but more the safety data of main (phosphoric acid) components. You asked, but your milage may vary.
I've been looking at some rust dissolvers/converters to spray inside of the rocker panels of my OT DD when I do some rust repair work. Does Ospho require any rinsing, or can I just spray it into the cavity and leave it?
OK, I broke down and bought a gallon of Ospho. Still don't know if it's any better than the regular stuff you get at the hardware store, but not worth taking a chance, it's only $28 bucks a gallon. Really only need about a pint or so, but a gallon is all I could find locally. Plus, Amazon sells the quart for $20.65, so not worth the small savings for a smaller jug, and have to wait for it to arrive.
If you need some, I'm sure I'll have plenty left over, and not far from southern Maine. PM me if you need it.
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