Lead time

[xilman]

Not sure whether to post in the Happy Me or Unhappy Me threads, so it is here.

Background: the supplied counterbalance weights on a 25cm Meade Schmidt-Newtonian are not heavy enough. I happen to have accumulated something over 50kg of lead in home-cast ingots.

Today I melted down 5 ingots (5-10kg in total perhaps) in an old paint can on top of a gas stove. Stank something horrible until the remaining dried paint had burned off but the extractor fan and open door and window ameliorated that. Roughly 30 minutes later there was pool of metal about 5cm deep, into which I plunged the wooden handle of an old hammer the diameter of which had already been measured to be the same size as the shaft on the telescope mount. The handle had been soaked in cold water because I did not want it to burn and because the steam would stop the metal adhering to the wood. A few hours later the can was cut off the now solid disk of lead and the hole cleaned up with a drill and a file until it was a smooth fit on the shaft.

It works beautifully as a counterweight. This is the Happy Me bit.

The Unhappy Me portion is that some molten lead splashed onto my right hand and, despite immediately plunging it into the cold water in which the wood had been soaked, I now have two mildly painful blisters each about 5x10mm in size. No permanent damage done but I am going to have to be careful for the next few days.

In case anyone asks: no, I am not in the least bit concerned about lead poisoning. The metal is of very low toxicity and ingesting a few tens of milligrams is not going to do me any significant damage before it is all excreted again. There are numerous individuals who have lived healthy lives for decades while carrying around several grams of lead inside them in locations where surgery to remove it is riskier than leaving it in situ.

[Dr Sardonicus]

Originally Posted by xilman

<snip>
Today I melted down 5 ingots (5-10kg in total perhaps) in an old paint can on top of a gas stove. Stank something horrible until the remaining dried paint had burned off but the extractor fan and open door and window ameliorated that.
<snip>
The Unhappy Me portion is that some molten lead splashed onto my right hand and, despite immediately plunging it into the cold water in which the wood had been soaked, I now have two mildly painful blisters each about 5x10mm in size. No permanent damage done but I am going to have to be careful for the next few days.

In case anyone asks: no, I am not in the least bit concerned about lead poisoning. The metal is of very low toxicity and ingesting a few tens of milligrams is not going to do me any significant damage before it is all excreted again.
<snip>

Ingesting? In your situation (melting down kilograms of lead over a gas flame), I would think inhalation was the main route of entry.

From what I have read about inhaling lead fumes, I hope you don't do something similar any time soon.

I hope your burns heal up OK.

[xilman]

Originally Posted by Dr Sardonicus

Ingesting? In your situation (melting down kilograms of lead over a gas flame), I would think inhalation was the main route of entry.

From what I have read about inhaling lead fumes, I hope you don't do something similar any time soon.

I hope your burns heal up OK.

I have no intention of smelting lead again any time soon because I now have no reason to do so. The original ingots were made in several batches a few weeks apart. (Incidentally, they came from stripped-out leaded windows and some plumbing that had been replaced with copper pipes.)

Whether gas or electric heating is irrelevant as the melting was done in a deep steel can which was covered for most of the time so as to keep in the heat.

You are correct wrt "ingestion". I ate very little, if any. I presumably inhaled a few dust particles and had to wash lead filings off my hands after finishing the job. Regardless, it was still only a few milligrams of the metal and nothing to worry about. The lungs have a very efficient dust removal mechanism and lead is very insoluble in our precious bodily fluids so there is even less to worry about.

Burns are entirely minor.

[pinhodecarlos]

Hope you have been grounded by swmbo.

[xilman]

Originally Posted by pinhodecarlos

Hope you have been grounded by swmbo.

Nope. She doesn't mind me doing things like this.

Seems pleased that it was successful and another step forward in getting the telescope in use again.

[Dr Sardonicus]

Originally Posted by xilman

<snip>
Whether gas or electric heating is irrelevant as the melting was done in a deep steel can which was covered for most of the time so as to keep in the heat.

Having a lid on the can probably helped.

I thought a gas flame was hotter than an electric heating element, and that that might matter.

I guess the folks in Ontario Ministry of Labour, Training and Skills Development don't know what they're talking about. They specifically mention high temperatures:

Lead fumes are produced when lead or lead-contaminated materials are heated to temperatures above 500°C, such as welding, high temperature cutting, and burning operations. The heating causes a vapour to be given off and the vapour condenses into solid fume particles.

I imagine, though, that once a pool of liquid formed in the bottom of the can, the temperature on top of the pool stayed well below 500 C. It probably was fairly close to the melting point of lead (around 327 C).

I guess the good folks at Michigan State University are a bunch of gibbering, capering alarmists. Of course, the following is geared to mitigating the hazard from an ongoing operation.

LEAD HAZARDS FROM CASTING BULLETS, SHOT, AND OTHER OBJECTS OR RELOADING

ESTABLISH A SMELT/CAST/RELOAD AREA

• Preferable location is outdoors, or, if you must do this indoors, mare sure your location is a separate area away from kitchen or food handling or storage.

• Do this on hard floors, without carpet, and surfaces that are easy to clean. Make some floor sweeping compound (sawdust, peat, dry dirt with an oil to make it clumpy, not wet). Dust it on the floor to catch the lead dust and keep it from getting back up in the air.

• Use lots of ventilation that exhausts air up and out, not around the room. A box or desk fan is just as bad as poor ventilation. Do not use home air systems which blow dust throughout the home.

• Never eat, drink, chew gum, or smoke or have these items in the area. Lead will settle on these objects and you will eat or inhale the dust.

• Use rubber gloves and dust mask with special filters for lead when handling solid lead ingots, bullets and dross. Store dross in a closed container.

• Melt lead below 900°F

• Do not sweep dry floors. Use a shop-vac with HEPA filter to vacuum up your area and your clothes once you are done. Don't use this vacuum for anything else. DO NOT use the house vacuum.

• Wipe down your work areas after casting with a damp disposable cloth or mop, using a separate bucket system to keep wash water separate from rinse water.

• Keep children and women of childbearing age clear of the smelting/casting/reloading area. Children are more likely to come in contact with dust and get it in their mouth.

• Launder clothing worn during casting or reloading separate from other laundry.

• Shower off after smelting or casting. Be sure to wash your hair too. Always wash hands after handling lead, particularly before eating or smoking cigarettes.

[xilman]

Originally Posted by Dr Sardonicus

I imagine, though, that once a pool of liquid formed in the bottom of the can, the temperature on top of the pool stayed well below 500 C. It probably was fairly close to the melting point of lead (around 327 C).

You imagine correctly.

Originally Posted by Dr Sardonicus

I guess the good folks at Michigan State University are a bunch of gibbering, capering alarmists. Of course, the following is geared to mitigating the hazard from an ongoing operation.

LEAD HAZARDS FROM CASTING BULLETS, SHOT, AND OTHER OBJECTS OR RELOADING

You guess incorrectly.

Tell me, have you ever come across the phrase "ass-covering"?

[Dr Sardonicus]

Originally Posted by xilman

You guess incorrectly.

Tell me, have you ever come across the phrase "ass-covering"?

'Course, silly! I don't see how it applies here, though.

I imagine I inhaled a fair bit of lead in my youth, due to the prevalence of leaded gasoline as a motor fuel.

Curiously, my dad had a glass bottle -- from a pharmacy I think -- of a lead compound in solution for use as an astringent to help dry up weeping sores (from a case of shingles if memory serves). The compound was lead acetate, which my dad said was also called "sugar of lead."

I guess it was in the past actually used as a sweetener. Yipes!

[PhilF]

I've been handling lead based solder almost daily since I was 10, so that's about 53 years now, and still counting.

Speaking of counting, you would think that I would no longer be able to count according to some lead poisoning alarmists.

On the other hand, maybe it explains my stupidity when it comes to math. I'm a computer guy, not a math guy. So I have to be very careful around here in order to avoid being annoying or offensive.

Sometimes I fail.

[xilman]

Originally Posted by Dr Sardonicus

'Course, silly! I don't see how it applies here, though.

Think: you, either as an individual or in your professional capacity as a member of an organization, are tasked with producing a safety information leaflet.

It would be quite courageous of you NOT to mention almost every hazard you can imagine and then go on to recommend robust countermeasures. What would happen if you omitted something and then someone managed to damage themselves as a consequence of an unusual set of circumstances augmented by rank stupidity?

[Dr Sardonicus]

Originally Posted by xilman

Think: you, either as an individual or in your professional capacity as a member of an organization, are tasked with producing a safety information leaflet.

It would be quite courageous of you NOT to mention almost every hazard you can imagine and then go on to recommend robust countermeasures. What would happen if you omitted something and then someone managed to damage themselves as a consequence of an unusual set of circumstances augmented by rank stupidity?

The publication I linked to doesn't deal with the other-than-toxic hazards of smelting and casting any metal, which can cause more immediate problems -- like spattering of molten metal.

Sue the bastards!