Saw Restoration: Carbon electrode Electrolysis + Foiling

[bill tindall]

PS

Your tank arrangement is ideal. Electrolysis is largely "line of sight" from anode to cathode. Having the anodes arranged around the item to be de-rusted provides a uniform current for de-rusting.

[Malcolm Schweizer]

Questioning the need for carbon....

What are you claiming the carbon does?

I am skeptical that the carbon has any effect on the result. I predict that if you replaced it with a stainless steel pipe or bar or spoon the result would be equivalent. Carbon is essentially inert and the only thing going on at the carbon is oxidation of water to oxygen, a process that occurs no matter what electrode is used.

In the case of using steel anodes, in addition to the oxidation of water the steel oxidizes to yield oxides and hydroxides of iron which appears as a nasty mess on the anodes. For this reason i don't use steel.

I use stainless steel for the anodes in de-rusting by electrolysis. The stainless steel doesn't dissolve and hence contributes nothing of significance to the bath. Never-the-less the derusted metal is grey. It is grey because some of red rust has been reduced to finely divided particles of iron and black oxides of iron. This deposit can be removed to reveal bare metal beneath, as what appears to be done with your aluminum treatment. But I predict the favorable result is from the aluminum abrasion and not the electrolysis, unless you have evidence to the contrary.

Never, ever, ever use stainless steel for electrodes. The byproduct is poisonous and cancer causing chromates. Read this:
http://antique-engines.com/stainless...electrodes.htm

[Moses Yoder]

Never, ever, ever use stainless steel for electrodes. The byproduct is poisonous and cancer causing chromates. Read this:
http://antique-engines.com/stainless...electrodes.htm

I would be interested in seeing valid documentation for that conclusion. Not saying it isn't true; all I am saying is I don't believe everything I read on the internet. Even when they use big words.

[Mel Miller]

I would be interested in seeing valid documentation for that conclusion. Not saying it isn't true; all I am saying is I don't believe everything I read on the internet. Even when they use big words.

Did you read the article in Malcom's link? Then, did you Google hexavalent chromate to learn more about it before refuting its' dangers? There are many articles online regarding the possible dangers of this stuff.

[bill tindall]

Refuting baloney with data

1. For those that use stainless steel electrodes, do you notice them going away. If they don't go away they don't generate anything soluble.

2. To bury this folklore some time ago I sampled a large cleaning bath a friend has and analyzed it for total soluble chromium species. He has used this bath for cleaning mountains of steel and he uses a stainless steel screen salvaged from a scrap metal business for an anode. The bath contained a few parts per million total chromium . I don't remember the exact figure but it was something like 3 ppm. I didn' t find this amount worrisome even if the chromium was present as chromate, which it may or may not have been. Analyzing specifically for chromate is more difficult than for total chromium and the low result didn't warrant the extra work.

3. The ever popular cheap nasty rebar anodes do dissolve and rebar may contain any element that gets recycled into rebar, including chromium. Additionally, old industrial metal being cleaned may have lead paint which winds up in the bath. The bottom line is that the bath may contain something toxic and it should be disposed of safely. Chromate is the least of your worries.

4. I published a detailed explanation of the chemistry of this process that can be found in the Articles Section of Woodcentral and elsewhere. Several internet posters have shamlessly plagiarized this article which contains the stainless steel recommendation. From time to time I receive shrill emails from concerned citizens warning me of the stainless steel danger and occasionally threatening legal action (no doubt these people are from CA). In each case I ask them for data to support their claims, but to date no one has provided any.

4. For those paranoid about chromate some facts would be helpful. It is a known carcinogen when the chromate dust is inhaled. Hence, those that use chromate for coloring wood, followed by sanding, do have a risk to worry about. It is less certain what the effects of low levels are from ingestion. Were it not for a technically flawed movie probably no one would have ever heard of it. In any case, it is difficult to imagine the risk of a tiny amount in a cleaning bath, if in fact any appears there.

5. The carbon electrodes do sound attractive if they are less expensive and or more easily attained than stainless steel. I hate rebar for chemical and clean-up reasons.

[bill tindall]

There are many authoritative sources of information on chromate toxicity. I doubt anyone questions the conclusions. What is being questioned, or in my case refuted, is whether using stainless steel anodes presents a risk. For those that think it does, lets see that data.

[Jim Koepke]

For those paranoid about chromate some facts would be helpful.

One concern is how to handle the waste when the bath needs to be changed.

Can the bath fluid from either carbon rod or stainless rod be safely dumped in the back yard or down the drain?

What about in areas with septic systems and wells?

It has been ages since I have worked with plating chemistry and that was only for a short time.

The process for removing rust is a reverse plating function.

Does anyone know if different electrodes effect the chemistry to pull different types of oxidation from the iron in the bath? (this could explain the difference in the result.)

There have been a few posts saying do not get the copper coated electrodes. What happens if copper is the electrode?

I have not yet used electrolysis in my shop.

Sorry if more questions are not what anyone wanted.

jtk

[Christian Castillo]

So far the fastest way I've found to make this whole process efficient is the following:

1. Electrolysis
2. Klingspor medium rust eraser to remove any dingy layer + Maroon Scotch brite to get into the teeth and clean them ( rust eraser would get chewed up)
3. Foil + Polish

IMG_20140713_151556407 by Christian Castillo1, on Flickr

IMG_20140720_104058815 by Christian Castillo1, on Flickr

IMG_20140720_104205720 by Christian Castillo1, on Flickr

The main difference I'm seeing from using carbon rods is the stubbornness of the greyish layer, It comes off very easy and doesn't require heavy abrasion to get past it. The whole set up is much much cleaner as well with carbon rods vs. rebar.

[bill tindall]

One concern is how to handle the waste when the bath needs to be changed.
Can the bath fluid from either carbon rod or stainless rod be safely dumped in the back yard or down the drain? If you are using carbon or stainless steel anodes AND you are dealing with just rust and not paint or what ever then the only thing in the bath is a moderately strong base, sodium carbonate, a compound commonly added to detergents and buttermilk baking recipes.



It has been ages since I have worked with plating chemistry and that was only for a short time....except for the involvement of electrons this process has nothing to do with plating chemistry.

The process for removing rust is a reverse plating function......No

Does anyone know if different electrodes effect the chemistry to pull different types of oxidation from the iron in the bath? (this could explain the difference in the result.) I cannot think of any involvement the inert (carbon or stainless steel) anode has other than to provide a source of electrons to the cathode. The actual voltage that gets to the rust might be less with carbon, for complicated reasons, but the actual voltage depends on many other factors as well. The oxidation is not pulled off. The oxides of iron are partially reduced in place, primarily to black iron oxide, magnetite, according to a study done for museum conservation. Additionally there is robust bubble formation at the rust which will blast off anything loose or capable of loosening. I think the bubbles may do about as much as the electrochemistry.

In the case of rebar the anode dissolves. What dissolves could impact the rust reduction.

There have been a few posts saying do not get the copper coated electrodes. What happens if copper is the electrode? The copper dissolves and replates on the iron where it promotes rapid corrosion.

I have not yet used electrolysis in my shop.

Sorry if more questions are not what anyone wanted.