I promise that this is my last epistle about electrolytic derusting.
It's just that I never could find out how much better Washing Soda is
than Baking Soda as the electrolyte for this process. So I ran a
controlled test and here are the results:
Again, very interesting Pete.
I was told that after soaking steel in vinegar to remove scale/rust it was
good to use a baking soda and water solution to neutralize the acid. But
when I went to the store to buy some baking soda, I found there was both
washing soda (with the detergents) and baking soda (with the baking
supplies) both made by the old standard Arm and Hammer. Reading the box, I
couldn't find anything to tell me if they were the same or different - and
at that point, I wasn't sure which I was told to use! I never realized
there where two types of Arm and Hammer soda.
But your page has now improved my education a bit on those two. My guess,
is that either would work, but that that the washing soda would neutralize
more acid per pound and that baking soda would be safer and milder to work
with. At least I now know there is a real difference between the two now.
However, doing some test, I really couldn't see any difference between
rinsing the piece in the baking soda solution vs just rinsing it with water
(or soap and water). Do you ever descale with vinegar? And do you rinse
the finished piece in anything other than water?
And does anyone know if baking soda or washing soda has any other
interesting uses in blacksmithing I should know about? :)
I'm glad it helped.
ABOUT DESCALING, NOT DERUSTING:
I have a friend who uses vinegar to descale most of the time. It takes
a long time to descale that way compared to other chemicals that I use.
Personally, I use much harsher chemical for descaling. Muriatic acid
that is available at hardware stores works well. An even stronger form
of the same (I think) acid is "The Works" toiler bowl cleaner. Use
either at your peril. Get serious about good ventilation. Even a few
wiffs of the stuff may give you a nosebleed. By the way, toilet bowl
cleaners that work on the basic side of the ph scale don't work for this
application, as far as I know.
To those who may be wondering, descaling and derusting are different
processes. Strong enough acids will do both, but they eat into the
iron itself during the process. The electrolytic derusting processs,
which is the topic of this original post will NOT remove scale!!! Only
Regarding neutralizing after acid descaling: I'm not surprised that the
soap and water gives about the same results. As long as you get all the
acid off the part, it will probably be neutral anyway. However, the
part will rust again quickly if you don't protect it, won't it?
Curt Welch wrote:
I have large plastic tanks that contain HCL (swimming pool acid) and the
other contains a bag (10#'s ) or two of Baking Soda.
I de-scale and then neutralize. When the soda that is on the bottom of
the tank starts to disappear, I add more. I want a well anti-acid bath
ready if I get a hand into acid or just my work. Welds a bit better without
Thanks for the great posting. I built the rig using one of those 5 gallon
white plastic paint buckets and 6 rebars, including two that were cut long
and bent into an "L" to cross the bottom. I couldn't find the Washing Soda
so I used the baking soda and hooked up the whole rig to an old auto battery
charger I had. It's almost like magic. Depending on how much amperage I
turn on, the fizzing is quite noticable. The parts come out just like your
pictures, black and pitted, but no red rust remaining.
Since gun blueing is actually an oxidized finish, would this technique work
to deblue a gun prior to rebluing? Or is gun "blue" the wrong kind of
oxidation? I don't have any that I want to risk on experimentation at this
time and wondered if any of you have tried it.
Sorry for the late reply.
No, I haven't tried that. And I don't know what the various blueing
methods really do. Might get some help from the Brownell's Gunsmith
Kinks books, tho. They are fun to read anyway.
It wouldn't hurt to contact Brownell's and simply ask them.
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