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Showing content with the highest reputation on 09/24/2012 in all areas

  1. just playing around with this one
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  2. Well if you didn't know this, remember that you heard it here first: All metals are toxic at some level, or in some form. The old adage that the dosage makes the poison is quite true. But it's easier to just say, "Lead is evil" and think no further. I've been asked to weigh-in on this discussion, so I'll shine what little light I can. Lost lead fishing tackle poses a fairly low risk to wildlife. The real threat comes from lead shot. Migratory waterfowl pick up tiny pebbles from river/lakeside gravel and swallow them into their crop to help grind up low-nutrition foodstuffs. Lead oxidizes to form a white coating on stray lead shot, and that helps birds see it and pick it up out of the sand and gravel. Once in the crop, the shot is ground with the other gravel and food and the lead oxide is ground into dust, mixed with acid in the bird's stomach, and forms lead acetate which is extremely toxic. The eventual result is a poisoned bird. Copper shot will also poison a bird. And a child eating leaded-paint chips will suffer the same. Remember, lead shot is fired at waterfowl right where waterfowl congregate and feed, and a single shotshell spreads hundreds of small bite-size lead pellets exactly where it can pose the most risk of bird ingestion. But even a single swan poisoned by a split-shot generates a whole lot of TV-time and bad publicity. Because of this fact, legislators have painted all lead-containing products with the same brush, and banned lead in many areas. A small child can also be poisoned very seriously or even killed by eating too many supplemental iron tablets, and one does not generally consider iron to be toxic... but it certainly can be. One can state with fair confidence that the hazard posed to hobby lead casters is likewise from ingestion. In this case it's the dust that results from handling/melting/pouring lead. Fumes present no real hazard, and one who is more concerned with lead vapor inhalation from hobby lead pouring is likely to ignore the much more dangerous vector of ingestion. Lead "fumes" pose a threat almsot exclusively to the lead smelting and battery lead recycling industries. In those situations, lead is heated to temps between 1800 and 2200*F, and lead vapor protection is required. Lead begins to vaporize at around 1100*F. Hobbyist lead melting equipment never reaches these temps. At that temp the lead is red-hot and glowing, and one can see a slight whitish vapor that emanates from the glowing lead. This situation does not confront the hobbyist or small manufacturer. Even modest ventilation is enough to eliminate any possibility of lead vapor toxicity. Note: Smoke from refining scrap lead is petroleum, road grime, and who-knows-what-else smoke. Smoke is bad to breathe. Don't breathe it. Do you eat while or right after pouring lead? Do you not change your clothes after pouring and before eating? If you do, you risk increasing your lead intake. If you wash after pouring and keep your area clean, the boogeyman of lead poisoning will stay comfortably under the bed. Soap and water works fine, but there are detergent products available to clean up lead dust. Lead sinkers in the environment-- contrary to popular opinion-- pose virtually no risk to wildlife or water quality. Exposed lead is soon covered with a layer of lead oxides and calcium oxide. Lead oxide is stable, is not water-soluble, and does not pollute groundwater. Unless you drop it on your head or eat it, it'll sit quietly in the mud forever and pose no risk. Zinc toxicity is of even lesser concern. Zinc vapors do not present a problem unless one is smelting and alloying brass. Those temps are not practical or really even possible for the hobby lure caster, and the cost of copper presents an economic barrier anyway. Zinc is an essential mineral in the body (unlike lead), and is metabolized in a water soluble form. What isn't metabolized is eliminated fairly quickly, and toxicity requires ingestion of extremely large amounts of zinc over a short time. In the environment (anywhere outdoors actually) exposed zinc oxides rapidly to ZnO, which is not water soluble and is regarded by the US FDA as a safe compound. Use of zinc for fishing lures is safe and quite responsible. Zinc does, however, present a higher burn risk than lead. As one who has set more than one crucible of zinc on fire I can assure you that you know when your zinc is giving off vapors. Tin has virtually no down-side, especially for smaller lures, other than cost. Density is lacking as compared with lead, but addition of bismuth helps, as has been noted previously. Now, even tin can be toxic, and some SuperFund sites are dealing with severely toxic tin pollution-- but that sort of pollution is industrial and isn't anything a tin caster would ever encounter. Tungsten is very expensive, very hard to work with, and thus very impractical. Brass alloys are likewise impractical for the hobby caster, require steel molds, pose metal vapor risks and also a severe burn risk. Not practical. What's left? Copper... expensive and toxic. Cadmium is absolutely wonderful for casting... but poses serious vapor and ingestion hazards. Iron? Nope, not practical. There aren't many cheap, commonly available metals left for consideration. Aluminum poses little toxic hazard and is cheap, but it's too light and too finicky to gravity pour into small molds. The answer is obvious: Be careful and responsible with whatever metal you use. It is easily possible to use lead safely and responsibly-- if you understand the risks and take precautions to avoid them. If you use tin or zinc, more power to ya. Hope this helps a little. Good luck and be safe!
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