Phosphoric Acid...

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  #1  
Old 02-28-05, 12:34 PM
Swat791
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Phosphoric Acid...

Does anyone use Phospho?

I was told you can use this acid to remove small amounts of rust and prevent rust on metal for a short time. The metal needs to painted as soon as possiable.

I was also told it will remove galvanization from metal.

Just apply it with a paint brush and let it set...

Any adivse on this.

Thanks,
Donnie
 
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Old 02-28-05, 03:53 PM
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Donnie,

Does anyone use Phospho?
I will be.
I have been using muriatic acid for cleaning because of the difficulty in having concentrated phosphoric shipped to my rural location.
I never seem to find the time to pick some up when I travel to my home city.
It is available to me in a 2 litre (about two qts) container at an 80% concentration for about $35.00 CDN.
Hardware store muriatic usually comes diluted to 20% so I could dilute it four times to get the same concentration.

Muriatic does a good job of cleaning but it will attack the metal surface as well as the rust and must be neutralized.

When using phosphoric the metal has to be reasonably clean when you start.
Depending on how rusted you're talking. If you clean the surface with a wire wheel and can then pressure wash the pitting, when dry the phosphoric will then finish it off.
The blue/black coating will be from converting the remaining rust to an inert material and will help the paint bond.
It will offer some protection if left unpainted but only for a short time.
 
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Old 03-01-05, 09:54 AM
J
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Jasco sells rust converter (its green,phoshoric acid) in 1 gal (about $15). I use lots of it for rust conversion prior to paint. Available at H.D., Ace hardware, and building or Painting stores. It will eat light galvanizing off (like corrugated roof has). Phospho is similiar. Never heard of using muriatic instead of phosphoric acid for conversion although any acid (including vinagar) will clean things.
 
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Old 03-01-05, 10:11 AM
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jeffk,

Commercial phosphoric rust removers that are available to me right now are nowhere as inexpensive as what yours costs.

What make is the rust remover you use and does the label say the concentration of phosphoric acid?
If it was at 20% then the industrial strength I can get when diluted would work out to $17.50CDN/gal.

I'll look a bit harder, maybe it's available, just not stocked.

Muriatic acid is not the ideal product for cleaning metal because of needing to be neutralized, but it's nature to agressively attack metal as well as the rust makes it ideal for cleaning cast iron parts.
Suspension parts, springs and brackets etc, clean up like new when soaked in muriatic.
 
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Old 03-01-05, 08:57 PM
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Jasco makes all kinds of painting products notably paint remover. Their product I use is called "Prep and Prime", is green contains phosphoric acid, wetting agents and something else can't remember now (doesn't list %). I pay from $14-$16 depending on where. Have bought here (CA.) and hawaii, and I believe Jasco is nationwide co. You brush, dip, spray (i use a spray bottle), let dry, when done turns black after turning iron oxide to iron phosphate. Then prime, paint (oil or harder- like automotive). Phospho is the same and price is usually about $16-$18/gal.
 
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Old 03-01-05, 09:52 PM
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Navel Jelly

I am not familiar with Phospho, but Navel Jelly has been used for decades. It does contain Phosphoric Acid, which converts rust (iron oxide) into Iron Phosphate, which is then ready for a good primer, and the rust will not appear thru the final coat.

Navel Jelly is sold in Home Depot, Lowes, and most hardware stores. It is truly a jelly, and is great for brushing on, and sticking to vertical surfaces. It needs to be thoroughly rinsed off but is excellent for removing rust.

Note: Do not use it on guns, unless you plan to re-blue them, it will remove the original bluing.

As with any acid, use proper protective equipment.
 
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