22 September 2013
Wheel weights are used to balance car wheels so that they don't vibrate as one drives. Unfortunately many of them are made of lead (a rather toxic metal) and are secured with a feeble clip that breaks easily. The result is that roads are covered in lost wheel weights. Any cycle trip can yield a nice collection. I threw out the ones made of iron, zinc, or some alloy, and saved the lead ones.
Another source of lead pollution comes from fishermen. They use lead weights to keep their hooks submerged, hooks that often get snagged and are lost. Kayaking under piers often reveals a hanging forest of fishing hooks and lead weights.
Yet another source of lead pollution comes from oil-spill flotation booms. These rubber curtains float vertically in the water, oriented by styrofoam floats at the top and lead weights at the bottom. Bits of broken booms often wash up on beaches.
Once my collection reached 15 kg, I threw it all in a pot and melted it down. As the wheel weights melt they release the steel clips which float to the surface. It is really neat to see steel floating. Once all the clips, oxidized lead, and other debris was skimmed off the top, I was left with 11.5 kg of pure lead.
With a density more than 10 times greater than water, it's a rather impressive block of metal. It's also kind of scary to look at and imagine that quantity of lead floating around in the environment. Eventually I'll mold it into counterweights for a future project.