Saturday, February 2, 2013

Aging Objects with Electrolysis

In my previous post I described how I used electrolysis to clean the rust from an old hand plane. During that process I observed the violent corrosion of the anode. In 24 hours in the electrolytic bath it aged considerably to the point of looking really old.

After doing some research I realized that most - if not all - types of metal corrosion are due to some form of electrolysis or another. In fact many sources state that electrolysis and corrosion are one and the same in the sense that there wouldn't be any metal corrosion without an electrolytic process of some kind.

That gave me the idea of using electrolysis to attempt to recreate the charm and beauty of a corroded metallic object. In other words, could I take a brand new metallic object and corrode it with electrolysis to the point of acquiring, in just a few hours, a much older look? What would I learn in the process? There was only a way to find out.

The first step was to find a suitable metallic object that would seem to benefit from an aged look. On my way back to work I stopped at a thrift store and bought a couple of metallic candlesticks for about $2.00. Here is a picture of how they looked as purchased:



I decided to experiment only on one of them in order to maintain a "before" and "after" live comparison throughout the process. I prepared an electrolytic bath using an old tin can without top or bottom as the cathode - that is, connected to the negative pole a battery charger - and the candlestick as the anode - connected to the positive of the same battery charger.

As an electrolyte I decided to use water and a generous amount of table salt. While I usually use washing soda to electrolytically clean objects, I thought that using salt for this corrosion experiment would be better since salt is notoriously harsh on metal and might give better results when the goal is to destroy.

I prepared the electrolyte in a one gallon plastic bucket, placed the tin can in the electrolyte, and the candlestick inside the can resting on the bottom of the bucket. Since the can had the bottom removed, there was no contact between the two and the candlestick was completely surrounded by the anode, which aids to the process.

I then connected the tin can to the negative of a 10Amps battery charger, and the positive to the candlestick. Immediately after turning on the charger, hydrogen and oxygen bubbles started pouring out the metal confirming that the electrolytic process had started (hydrogen and oxygen are an explosive mixture in the right circumstances, so do not try this at home without proper research and precautions).

Here is a photo of how the setup looked after one hour:


You can see the electrolyte covered by corroded metal sludge.

After one hour I decided to take a peek. As you can see from the below photo of a side-to-side comparison between the corroded candlestick (left) and the untouched one (right), the surface coating - made of either zinc or silver I assume - had gone, revealing the real nature of the core metal: copper.

While this was a decent result, I wanted to bring the process much further so I reconnected the candlestick, submerged it in the electrolyte inside the tin can and started the electrolysis again. This time I let it go for 24 hours.

The next day I checked, and here is how it came out after a good rinse in water and some light scrubbing:

 

Looks interesting and certainly very old. Note toward the top a series of small holes that show how much corrosion the metal went through in only 24 hours. Some close ups:





 

This is an interesting look, and it certainly looks old. However it looks "dirty". This might or might not be a good thing depending on what the desired look is. I considered leaving this as-is, but I was curious to see how the piece would look cleaned up of the greenish product of the copper corrosion.

After a few minutes with a brush wheel, here is the clean result:

 







So, what do you think? Do you prefer the original? or the lightly corroderd? Or the heavily corroded "dirty"? Or the heavily corroded "clean"?

 

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