Testing pewter for lead content

The most common answer given for testing pewter for lead is to dissolve a sample in dilute nitric acid and add a drop of potassium iodide.

So here is the problem with this method. Lead iodide is a yellow precipitate, and tin iodide is a yellow-orange precipitate. It seems to me this method leaves a lot of room for interpretation and isn't very definitive.

Is there a more accurate test that doesn't require expensive testing equipment or a high degree of guess work?

Add some HCl and any lead in your nitric will form a chloride.

Oz said:

Add some HCl and any lead in your nitric will form a chloride.

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also silver...


some pewter might be silver plated.

Oz said:

Add some HCl and any lead in your nitric will form a chloride.

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The truly old stuff has collector value and is sold as is.

Of the modern crap the goal was primarily to sort lead free from the leaded. Lead free pewter being 92-97% tin has a high scrap value (approximately $4.80/pound) and can be sold without refining. Leaded pewter trades at scrap lead solder prices(around $.70) unless you want to set up to refine it or make fishing weights.

also silver...
some pewter might be silver plated.

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I have a small amount of this and I save it separately as well.

How about dissolve a small sample in HCl, heat it to get all Pb-chloride into solution, filter, add sulphuric acid to precipitate lead sulphate, filter or decant the solution off, dry the precipitation and finally weigh if you want a quantitative analyze.

If you only need an indication of lead then stop after precipitation of the lead sulphate.

False positives in this test could be mercury if my memory works.

/Göran

Thanks guys.

I'll have to try some test samples.

qst42know said:

Lead free pewter being 92-97% tin has a high scrap value (approximately $4.80/pound) and can be sold without refining.

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I saw that $4.80 lb and decided to give it a try. I see pewter every week at yardsales. But then I talked to my scrap buyer. He will only pay 70¢ a pound.

If I could get close to $5 it might pay to ship by priority mail.

The plan was 70 pound Priority flat rate boxes. I haven't gotten back to the testing as yet. The key to this being viable is confirming it to be lead free.

Don't go loading up on this yet it's just an idea of mine.

I exchanged a few emails with a fellow at Rotometals. That's where I got the numbers from. I forgot to ask if there would be a fee for an ICP test. In which case melting all into a single ingot would be required and that's why it would be vital to be certain all was lead free.

qst42know said:

Don't go loading up on this yet it's just an idea of mine.

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Let me know the final outcome. I had the same idea this weekend and passed up on 6 heavy steins. I am sure they would be lead free but not worth it at 70¢ a pound.

The 70# box will not hold much because of its size, but pewter melts very easy. I used to make pewter jewelry in my younger days.

rotometals is only 396 miles from me so I guess I would still have to mail.

qst42know said:

Don't go loading up on this yet it's just an idea of mine.

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I called them yesterday because I needed an answer before saturday, when I do my metal hunting.

Right now they offered $3.00 lb for lead free and "less than" 70¢ lb if it had lead in it. He also said depending on the test they may even reject some.

Parcel post from SoCA is about $30 for 50 lbs I will do a test batch of 50lbs and let you all know what the outcome is. May take several months to find that much.

I think I will start looking for any pewter that was designed for eating or drinking and hopefully it will be lead free. I see a lot of candlesticks and decorative plates I will not even consider.

Thoroughly modern stuff that isn't imported should be safe as OSHA monitored blood testing of your work force would be a cost any manufacturer would want to avoid. I don't think rotometals will care one way or another if the items were pounded flat in which case a Priority mail flat rate box may be a cheaper shipping option.

What did they say about the ICP testing, is there a charge?

qst42know said:

What did they say about the ICP testing, is there a charge?

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If they are buying - no charge. 8)

I buy at yardsales so most everything will be older. I plan on compacting everything as much as possible. I have worked with pewter before, easy to cut easy to pound.