You could probably save yourself some money here.
Oren's recommendation of Loctite's Naval Jelly Rust Dissolver utilizes a
well known chemical reaction between rust and phosphoric acid that
converts the rust into a black compound called Ferric Phosphate or
Here's what Wikipedia says about using Phosphoric acid to convert rust
to Ferric Phosphate:
'Phosphoric acid - Wikipedia, the free encyclopedia'
Phosphoric acid may be used as a "rust converter", by direct application
to rusted iron, steel tools, or surfaces. The phosphoric acid converts
reddish-brown iron(III) oxide, Fe2O3 (rust) to black ferric phosphate,
"Rust converter" is sometimes a greenish liquid suitable for dipping (in
the same sort of acid bath as is used for pickling metal), but it is
more often formulated as a gel, commonly called "naval jelly". It is
sometimes sold under other names, such as "rust remover" or "rust
killer". As a thick gel, it may be applied to sloping, vertical, or even
After treatment, the black ferric-phosphate coating can be scrubbed off,
leaving a fresh metal surface. Multiple applications of phosphoric acid
may be required to remove all rust. The black phosphate coating can also
be left in place, where it will provide moderate further corrosion
resistance (such protection is also provided by the superficially
similar Parkerizing and blued electrochemical conversion coating
So, I took a look at the MSDS for Loctite Naval Jelly Rust Dissolver,
and sure enough it's mostly phosphoric acid. It's got 10 to 30 percent
phosphoric acid in it. It's got some other stuff in it too, but those
other things are to gel it so that it can be applied to vertical
surfaces and overhead:
'Household Products Database - Health and Safety Information on
Household Products' (http://tinyurl.com/bfjgnv8 )
Now, phosphoric acid is commonly used as the active ingredient in toilet
bowl cleaners. If you just go down to your local home center or
hardware store and look at the toilet bowl cleaners they sell, many of
them will give a phosphoric acid content, or have a warning saying that
it contains phosphoric acid.
Here's a phosphoric acid based toilet bowl cleaner being marketed by a
company called "Iowa Prison Industries":
If Loctite Naval Jelly Rust Dissolver has a phosphoric acid content of
10 to 30 percent, you can use any phosphoric acid toilet bowl cleaner
with a phosphoric acid content between 10 and 30 percent to get
identical results as you'd get with the Loctite product.
Many toilet bowl cleaners will contain hydrochloric acid, but you want
to use phosphoric acid for converting rust into that stable black
compound, ferric phosphate.
Also, EVERY janitorial supply store listed under "Janitorial Equipment &
Supplies" will, in all certainty, sell a phosphoric acid toilet bowl
cleaner you can use on your tools.
Phosphoric acid is a mild acid. It's about the same strength as CLR.
It won't harm your tools if you leave it on too long, but doing that
won't remove any more rust. Once the rust turns black, just wash the
remaining phosphoric acid off your tools with water and dry immediately
with a rag or paper towels.
Rubbing oil over the ferric phosphate won't do anything, and it'll only
make dirt stick to your tools. I would leave out the business about
applying oil to anything because as soon as you use that tool, the oil
film will get wiped/rubbed off anyway. Just keep your tools dry.