2airishuman
Contributor
Why do we still use lead dive weights? How much longer will they be common?
Lead is toxic and poses various environmental, handling, and disposal problems. Since the 1970s, there has been a gradual effort worldwide to reduce worker exposures to lead, and to reduce the amount of lead released into the environment:
1) It is dense, at 11 grams/cc, so that weights need not be large.
2) It has good compatibility with salt water.
3) It is relatively inexpensive.
There are other alternatives. Iron, at 8 grams/cc, is heavy enough, and cheaper than lead, and is useful if encapsulated (by plating or coating) or alloyed to prevent corrosion. Bismuth is non-corrosive, and widely used as a lead replacement, but is expensive ($15/pound) and production is not sustainable. Many other metals in widespread industrial use are workable alone or in combination and reasonably priced -- copper, tin, etc. Of all these, iron in the form of stainless steel, is perhaps the most plausible replacement.
Lead is toxic and poses various environmental, handling, and disposal problems. Since the 1970s, there has been a gradual effort worldwide to reduce worker exposures to lead, and to reduce the amount of lead released into the environment:
- Lead birdshot was outlawed for hunting of migratory waterfowl in the 1970s, with restrictions gradually affecting other types of hunting also.
- The Restriction of Hazardous Substances Directive, adopted in 2003, caused a worldwide move to lead-free solder in electronic products.
- Increasing regulatory burden and enforcement in specific market areas, e.g. children's toys, paint
1) It is dense, at 11 grams/cc, so that weights need not be large.
2) It has good compatibility with salt water.
3) It is relatively inexpensive.
There are other alternatives. Iron, at 8 grams/cc, is heavy enough, and cheaper than lead, and is useful if encapsulated (by plating or coating) or alloyed to prevent corrosion. Bismuth is non-corrosive, and widely used as a lead replacement, but is expensive ($15/pound) and production is not sustainable. Many other metals in widespread industrial use are workable alone or in combination and reasonably priced -- copper, tin, etc. Of all these, iron in the form of stainless steel, is perhaps the most plausible replacement.