F. George McDuffee wrote:
On 23 Nov 2008 04:01:42 GMT,
(Old Chipper) wrote:


New Member here! Hello all!
Anyone have a cheap (reasonable) recipe for a chemical rust remover that
can be used in removing medium to heavy rust? I'm always restoring or
reclying something that has rusted. I'm aware of the dangers that can be
involved. We used to do plating, etc. in the shop I worked in. Jenolite or
Naval Jelly is made from what? I was told they contain Phosphoric acid,
but what percentage?
I'm not in a hurry, so even a "greener" solution would be okay!

-----------
Be remined that Naval Jelly does not remove rust but converts it
from the red to black oxide. Best solution appears to be
electrolitic cleaning. Use a plastic storage container from
walmart for the tank and your battery charger. Several threads
on this in this NG.

Usual solution is washing soda [baking soda also works] at the
rate of a tablespoon to the gallon, which is pretty tame.

google on "electrolytic derusting" for 700 hits.
start with
http://www.stovebolt.com/techtips/rust/electrolysis.pdf
http://www.woodmangler.com/Derusting...derusting.html
http://www.vhfsouth.org/tutorials/derusting.htm



DONT EVER USE A STAINLESS STEEL ANODE or you'll risk making some
seriously toxic waste. Only do it in a well ventilated area as Hydrogen
gas is produced in significant quantities.

The archeologists use electrolytic derusting at very low current levels
to conserve iron cannon and the like. They are interested in preserving
every last detail of the surface they can. For the rest of us, a quick
result that doesn't do significant damage is preferable. For most
things its good if you are passing enough current to keep the derusting
bath warm, but you dont want it to boil.

I'd strongly reccomend putting some sort of ballast resistor in series
with the power supply to limit the current in the event of a short
circuit. Avoids all sorts of unwanted excitement. I usually use a car
headlamp bulb which at 60 watts rating will pass 5 amps when shorted. If
things are going well, it will be glowing dull red for most parts thast
will fit in a tank of about 2 litre capacity.

It helps to keep the worst of the corrosion knocked off the anode by
wire brushing it at intervals if you are either doing several parts or
have something big derusting over several days.

It works well with just about any alkali. A drop of detergent in the
solution can help with wetting. Used solution can be stood till it
settles and kept for next time.

P.S. Iggy, your favorite hydrochloric acid rust removal method works
pretty well for bulk rust removal but will etch away some good metal and
leaves the surface chloride contaminated which will make further rust
damage more likely. If you used the acid to get 90% of the rust off,
washed the object well then finished it by electrolytic derusting, you'd
get a much superior result.