Saturday, 30 June 2012

Elephant No. 272: Rust

I've been wondering for a while how to create instant rust, so today I thought I'd make a serious effort to try it.

Rust is the generic term for iron oxide, and usually refers to the red oxides formed when iron reacts with oxygen and water. Interestingly, there is also "green" rust, which results when iron reacts with chlorides in oxygen-deprived environments, such as the iron rebar in underwater concrete pilings.

Various colours of rust on iron.
Photo: Laitr Keiows, 2010

Given enough time, and lack of protection, any iron material exposed to oxygen, water and/or chlorides will turn into rust and fall apart. Water alone will rust iron-based materials, and when exposed to salt as in seaspray, it will rust more quickly.

Heavily rusted chain near the Golden Gate Bridge, San Francisco.
Photo: Marlith, 2008

Because of the prevalence of iron and steel in the modern world, prevention of rust is important. Since rust is permeable to both air and water, the iron or steel beneath a layer of rust will continue to corrode. Rust is inhibited in several ways, including alloying iron and steel with metals that don't rust, plating the metal with zinc or chromium, covering the metal with a layer of oil or grease, painting, or varnishing. For smaller items, rust can  be inhibited by surrounding the metal with substances such as silica gel, which absorb moisture before it can affect the metal.

Although the most common effect of rust is disintegration, a build-up of rust can also force metal apart. Known as "rust smacking", this type of extreme rust has been responsible for the collapse of at least two steel bridges in recent years. Reinforced concrete is similarly vulnerable. As corrosion expands the metal inside the concrete, the concrete breaks apart, causing serious structural issues.

This kind of rust is so extensive that it could cause rust smacking if found in many
parts of a structure such as a bridge.

In addition to being the bane of every car-owner, bridge-builder, shipping firm and architect, rust has also entered the world of metaphor. Today, it is used in everything from books to songs to imply decay, since it has the ability to turn sturdy metal into a pile of powder.

Rusted-out car, Cooma, New South Wales, Australia.
Photo: Ken Myers/Black White Photography Art Gallery

The rust technique I chose for today's elephant was simple: spray an iron- or tin-based metal with hydrogen peroxide, then sprinkle with salt. Unfortunately, the simplest of things never seems to be simple for me. For the instructions I used—which were much better than my execution of them—click here.

I didn't have any appropriate metal at home, so I went out and bought some embossing tin. Just in case that didn't work, I bought a cookie sheet made with some sort of alloy that I was sure would rust, since similar cookie sheets have rusted in the past.

Neither of these metals worked, however, so I went to a nearby hardware store and bought a sheet of 16-gauge steel—not galvanized or stainless—which I was assured would rust. The fact that I wanted the sheet of metal to rust was somewhat mystifying to the clerk—this being a rather macho old-school hardware store—so I wasn't entirely sure, until I tried it, that I actually had what I needed.

I worked outside on my flagstone patio, because the solution is corrosive to metal. I started by masking off half of the sheet, so that I ended up with a working surface of about 30 x 30 cm (12 x 12 inches). I also laid the steel down on a piece of aluminum foil to avoid scratching the back. After all, you never know when you might need to use the back of something like this.

Next, I sprayed the surface liberally with hydrogen peroxide.

I used a single-hole shaker of salt to pour salt onto the surface in an elephant shape, which isn't as easy as I thought it would be. The metal began to rust at the edges of the salt almost instantly, as you can see in the photograph below. This panicked me a little, so I quickly pushed any errant blobs of salt into place. I also sprinkled bits of salt across the background to make the final background less blank and more integrated with the elephant.

The salt and hydrogen peroxide interacted very quickly, and not only bubbled but actually smoked at the start of the chemical reaction. There was also a faint odour of hydrogen sulphide, or rotten eggs. I left the piece to do its thing for awhile, checking periodically on it until it dried.

Once it had dried, I sprayed it with a garden house to remove the dried salt. This was a stupid idea, because it washed away a lot of the rusty patina, particularly on the elephant shape. Although the pitted surface was interesting on its own, it wasn't the rusty look I was going for. So I sprayed the surface with hydrogen peroxide again.

This reactivated the light salt specks in the background, but didn't really do much to the elephant, despite the amount of salt I'd loaded onto the elephant shape. Then I realized that, by overloading the area with salt, I may have kept oxygen from getting to the metal surface, inhibiting the red oxide from forming.

I kept at all this for another hour or so, fiddling with salt, sprays of hydrogen peroxide, washing things off gently, blotting, and so on. I still couldn't really get the elephant to turn red.

As a last resort, I painted hydrogen peroxide on the elephant shape, sprinkled it with salt and waited. Nothing much happened, so I poured hydrogen peroxide carefully on the elephant. Because I'd already painted the shape, the hydrogen peroxide that I poured stayed within the same lines. Pouring on hydrogen peroxide also caused a significant chemical reaction: large bubbles, lots of red oxide, and smoke.

This looked more like what I wanted, but I was a bit tired of the whole thing at this point. I decided that, if the elephant didn't show up properly when it dried, I would polish away the background or something. Then I decided it was taking too long to dry, so I took a hairdryer to it.

This was actually a really good idea. I don't know if it would have looked as nice if I'd let it air-dry; either way, it had the benefit of making me like the piece much more. The red oxide looked good, the grey-black pitting was appealing, and an interesting blue-white salt rim had formed around the edges. Although I brushed some of the salt away, I left a lot of it as a counterpoint to the rust.

If you try this, it's obviously going to take a bit of experimentation. I didn't have much to do today, so I didn't mind playing with it to a certain extent. I would, of course, have preferred it to do what I wanted right away, which was form a dark rusty elephant in the middle of a bunch of lighter rust specks. In the end, however, I got something I liked better.

The basic technique is very easy, and it's fun to watch the rust form. It's also relatively non-toxic, although obviously corrosive to metal. I started by wearing gloves, then got tired of them, but suffered no ill effects from either getting the stuff on my hands, or from any kind of odour. My greatest risk was probably the possibility of cutting myself on the razor-sharp edges of the steel.

Although I was frustrated by the technique when I started, I really like the final result. I will definitely use this again, and am already thinking of larger things I could rust in interesting patterns.

Elephant Lore of the Day
Although this is a sad story about elephants, it's also the first time that I've ever read of an elephant being considered a political activist.

In 2010, an elephant rampaged through a Liberian logging area, killing one of the workers. In previous weeks, the elephant had been known to threaten other logging employees, as well as local farmers, but this was the first time he had ever killed anyone.

Timber is one of the country's major exports, but its harvesting has become a cause of considerable conflict between rural Liberians and the logging companies. And in the rampaging elephant, ordinary Liberians saw a kind of superhero. The elephant, they said, was expressing the frustrations of Liberians who gain no benefit from the country's logging activity. Many Liberians even claimed that the elephant was supernaturally possessed by vengeful human spirits.

Despite the fact that elephants are endangered in Liberia and protected by law, a forestry official determined that the elephant would have to be killed in order to ensure the safety of residents. I'll spare you the details on how this particular elephant was put to death.

Following the elephant's death, forestry official Theophilus Freeman expressed regret over the killing of the elephant. He went on to say that, through a careful deductive process, local authorities had determined that the elephant had not, in fact, been possessed by humans. "Some people," said Freeman, "said there was a human being or two working in the elephant. But it's been two days since the killing of the elephant. If it were true that the elephant was possessed, one or two persons would have died by now." He further suggested that locals had only claimed that the elephant was possessed in order to extort concessions from the logging company.

This last comment infuriated local activists. They threatened legal action over the inference that they might try to use supernatural tactics against the logging industry. "We are a proud and decent people," said activist Hilary Mentoe, "how dare they think we would transform ourselves into an elephant in order to destroy lives and property!"

When the furor died down, nothing had changed. Except for the unfortunate loss of one of Liberia's few remaining elephants.

African forest elephant, Tanzania.
To Support Elephant Welfare
Elephant sanctuaries (this Wikipedia list allows you to click through to information
on a number of sanctuaries around the world)
Wildlife Trust of India

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