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I hope this is the right SE for this question. If not please point me in a better direction. I'm working on a project that requires a counterweight in a tight/organic space. I'm trying to maximize the weight so I need a dense material -- the denser the better. A material that's easy to machine would be OK, but ideally something that could conform to the space would be better.

These requirements led me to consider lead shot or lead wool as an option. My concern is obviously safety. I'm wondering if it is safe to encapsulate the lead with something like epoxy.

My understanding is that lead poisoning typically arrises from ingestion, inhalation, and dermal contact. I imagine that if I encapsulate the lead in something like epoxy then those three pathways are no longer relevant, but I'm just not sure and would rather avoid taking chances. Maybe the only risk is during the encapsulation process? Clearly lead is used in a variety of applications with human contact (e.g. lead vests for x-ray) so there must be someway to properly shield it from the surrounding environment.

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    It's not plutonium. So you can handle it just fine. Just don't chew on it or lick it for a long period of time or sand it and breath in all the dust. – DA01 Oct 14 '15 at 20:39
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    That said, it wouldn't be unsafe to do this. Just likely overkill. Unless this lead counterweight is going in a baby's crib or something. – DA01 Oct 14 '15 at 20:43
  • Thanks @DA01 -- what part do you think is overkill? Encapsulating it with epoxy or using lead in the first place? It's going in the base of a wooden lamp, which will be touched on the outside regularly, but there should be no reason for anyone to touch the inside where the weight sits. I just want to make sure that there's no way for the lead to leach through to the outside surface. – Doov Oct 14 '15 at 21:23
  • That's not really how lead works (it won't leach through the lamp base), so you'll be fine. If you are REALLY worried, just paint the lead weight to encapsulate. – DA01 Oct 14 '15 at 23:24
  • What is a "tight/organic space" - I'm not getting your "how you fear lead poisoning" issue from that description. Where's the human contact? – Ecnerwal Oct 15 '15 at 3:38
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You are correct in that lead is pretty inert, especially when encapsulated. I would only worry about proper disposal once you are done with it, and how you plan to shape it (since a drill or saw could cause lead to become airborne, hammering should be safer).

If you are worried about health and safety, perhaps a different metal could be used, though they're generally going to be more expensive than lead. Quickly looking at metal density tables, you may also be able to use tungsten (much heavier than lead).

Also, keep in mind that lead isn't that much heavier than other common metals. Lead is 11.3 g/cm^3 while iron is 7.8 g/cm^3 and nickel is 8.9 g/cm^3.

If you want something very dense, depleted uranium would be an excellent choice (except for the health concerns with respect to breathing or eating it and availability issues due to it being a controlled substance).

Gold is also pretty dense, and quite safe.

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  • Based on your densities, lead is 45% more dense than iron. I'd argue that is a pretty big increase. – JPhi1618 Oct 15 '15 at 14:17
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The only form of lead that is significantly absorbed through the skin is tetraethyl lead, which was found in gasoline long ago. That's not in lead shot, so you'll be fine on that count. The main way that lead becomes dangerous is if tiny lead particles are eaten or inhaled. Eating lead is significantly more dangerous for children since a higher percentage of eaten lead is absorbed vs pooped out.

As long as you avoid eating the lead shot or breathing in lead-bearing gasses (e.g. from deliberately inhaling smelting fumes or gunsmoke), you really have nothing to worry about. Just keep the lead shot in a plastic ziplock baggie or something and you've reduced the risk by 99.9%.

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Lead is not dangerous unless significant amounts are absorbed by the body. Unless the lead is in a solvent or a fine aerosol or is consumed in large quantities, this is not generally possible. Many houses have older windows with 10-lb lead sash counterweights in the frames.

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  • Well, depends on the definition of "significant". No safe dose has ever been found and children are more vulnerable than adults. – iLikeDirt Oct 14 '15 at 22:41
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Tungsten is considerably denser than lead. 19.3 g/cc .vs. 11.34 for lead

Evidently when tungsten weights are called for, "heavy alloy tungsten" is more commonly used since it's much easier to machine than pure tungsten, if extremely high heat resistance is not called for. that ranges from 17-18.5 g/cm based on some sloppy research.

On the third hand, 19.3 g/cm can also be had in gold, and is quite common for use in "human tissue contact" due to non-reactivity, if that's what "tight/organic" was driving at. Spendy, but so is poisoning people.

Oh, a wooden lamp base - pour it full of molten lead and call it a day. Or use plaster, concrete, ball bearings, etc...

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