#30:
Author: Jake, 
Posted: Sat Mar 29, 2008 2:03 pm
My experiment is electrolytic tank de-rusting
has been completed. As I initally reported the results were less than
expected using rebar as an electrode.
The test was repeated with
increased washing soda and using 9 isulation stays bundled together, and
the results improved.
Flash rust was immediate and probably just
as bad after each try.
My third and final attempt was the best,
but still not what I wanted. It removed rust in better quanities and
faster. This time I used an old sharping steel as the electrode.
Flash rust was not as rapid, and I put 2 old socks with desicant
in them to absorb moisture, but after 2 days it was back to where it
needed de-rusted again. I did not add oil or anything to it as I was
waiting on my POR-15 to arrive and did not want to go thru the process of
degreasing.
After I got my POR-15 ( sealer only, not the kit ), I
used white vinegar, it worked reasonably, flushed with hot water. followed
by denatured alcohol and dried.
After drying, the next day I
discovered powdered rust laying in the bottom of the tank and once again
the flash rust.
Now, my POR-15 had arrived. Shop vac removed the
powder easily, and I didn't want to use the vinegar approach or
eletrolytic method again, so off to the hardware store I go.
Muratic acid was considered as a last resort. I work with the
stuff a few times a week and without a respirator at home, was not the
preferred route.
Phosphoric acid was what I was looking for and I
found some at a Mom and Pop hardware store for $10 a quart.
8
ounces of that and 5 minutes of sloshing around later, I was completely
satisfied. I drained,let dry over night, rinsed with warm water, a few
ounces of denatured alcohol to remove the left over water. Inserted hose
from the shop vac ( attached to the blower end ), left to dry for a half
an hour.
Rust ? Yep, but just discolored, like a little overspray
from orange paint, besides, the POR will bond nicely with a small amount
of flash rust.
8 ounces of POR-15 and I'm a happy camper. Ready
for paint, new manual petcock and then I'll mount it.
In
conclusion, the eletrolytic approach does work, is cheap, but does take
lots of time to work, and will rust soon after if not treated with
something immediately. Using high carbon steel will yield better results
than using rebar. Rebar is low quality steel and has not much carbon
making it very slow to rust, which is why it is used in construction.
I would not recommend this method for a tank, from my own
experience, but works great on items you can oil or put some kind of rust
inhibitor on soon after.
|