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From: N_Cook on 8 Apr 2010 09:37
Given up on chemical tests , no consistency/ lack of differentiation.
Mortar and pestle idea goes no where.

Had to decide this week whether a 2003 board had failed solder due to SnPb
or PbF and excess heat , where it was used. Could not decide by appearance,
good mirror finish, lack of pastiness but solder joints too shallow to tell
domed from conical, so probably SnPb.
Low temp soldering iron test, melted - SnPb
Paper test - SnPb
and indentation test much nearer Pb diameter than Al so - SnPb


From: Archon on 8 Apr 2010 13:12
N_Cook wrote:
> Part 1 a couple of weeks back , using low temperature set soldering iron.
>
> Have tried chemically using both potassium chromate and potassium iodide but
> cannot make either work with elemental/eutectic lead. Not having a source of
> conc nitric acid and colour of tin iodide being orange and tin chromate
> being brown, so not that different to the yellow lead salts, may not have
> worked anyway. I gave up along those lines after trying boiling up with
> acetic acid and separately washing soda failed.
>
> 2 more physical tests.
> Grey mark on paper.
> Scrape back surface of the solder and rub a specific number of times with
> some copier paper over a cocktail stick. Leaded solder leaves a much darker
> grey mark, nearer black, on the paper.
>
> Indentation test shows promise.
> The following using a well worn automatic centre punch, so a new sharper one
> for use only on soft metals is probably called for. This one, existing
> spring replaced with a lighter one giving a load before trigger of 3.5Kg.
> Comparing block of copper,Al, roofing lead and off the roll solder
> wire,63/37 and 85.5/4/.5 silver solder laid over the lead as a soft anvil.
> Steel rule with 1/100 inch markings and a x30 basic microscope
> Measuring diameters of the indentations (x10 thou/mil)
> Cu 1.5
> Al 2.5
> high tin solder 3
> SnPb 4
> Pb 5
>
>
> --
> Diverse Devices, Southampton, England
> electronic hints and repair briefs , schematics/manuals list on
> http://diverse.4mg.com/index.htm
>
>
>
You need this, expensive though, or find out whats in the tester chemicals.

http://www.amazon.com/Homax-5250-Household-Lead-Test/dp/B000E3DX0C

JC
From: Archon on 8 Apr 2010 13:15
Archon wrote:
> N_Cook wrote:
>> Part 1 a couple of weeks back , using low temperature set soldering iron.
>>
>> Have tried chemically using both potassium chromate and potassium
>> iodide but
>> cannot make either work with elemental/eutectic lead. Not having a
>> source of
>> conc nitric acid and colour of tin iodide being orange and tin chromate
>> being brown, so not that different to the yellow lead salts, may not have
>> worked anyway. I gave up along those lines after trying boiling up with
>> acetic acid and separately washing soda failed.
>>
>> 2 more physical tests.
>> Grey mark on paper.
>> Scrape back surface of the solder and rub a specific number of times with
>> some copier paper over a cocktail stick. Leaded solder leaves a much
>> darker
>> grey mark, nearer black, on the paper.
>>
>> Indentation test shows promise.
>> The following using a well worn automatic centre punch, so a new
>> sharper one
>> for use only on soft metals is probably called for. This one, existing
>> spring replaced with a lighter one giving a load before trigger of 3.5Kg.
>> Comparing block of copper,Al, roofing lead and off the roll solder
>> wire,63/37 and 85.5/4/.5 silver solder laid over the lead as a soft
>> anvil.
>> Steel rule with 1/100 inch markings and a x30 basic microscope
>> Measuring diameters of the indentations (x10 thou/mil)
>> Cu 1.5
>> Al 2.5
>> high tin solder 3
>> SnPb 4
>> Pb 5
>>
>>
>> --
>> Diverse Devices, Southampton, England
>> electronic hints and repair briefs , schematics/manuals list on
>> http://diverse.4mg.com/index.htm
>>
>>
>>
> You need this, expensive though, or find out whats in the tester chemicals.
>
> http://www.amazon.com/Homax-5250-Household-Lead-Test/dp/B000E3DX0C
>
> JC
or this
http://www.ojp.usdoj.gov/nij/training/firearms-training/module12/fir_m12_t05_03_j.htm
From: N_Cook on 13 Apr 2010 07:41
Got some spirit of salts (32 percent hydrochloric acid) from a traditional
hardware shop. No colour reaction found heated with leaded solder and then
KI.
Also got a pot of sulphur and may try excessive heating as there seems to be
some sort of test that way producing a black lead sulphide colour.



From: N_Cook on 14 Apr 2010 03:39
I increased sample sizes to about 3cc of 32% HCl and about 30 cu-mm of
solder wire. About 1/3 of the wire scraped into scrapings and remainder
added as round and the part round remnant . After boiling and cooling twice
then perhaps about 5 to 10 cu-mm of KI added and repeated boiling and
cooling. For the leaded one bright orange crystals? soon appear on forced
cooling and flecks of glistening gold colour the second time of heating
cooling after KI . The glistening gold agrees with my chemistry book for
lead testing with KI, don't know about the orange. The colours and crystals
disappear on boiling.

The lead free one , no colours at all in the liquid but the metal goes
black. With repeated boiling then still a lot of gas comes off the metal for
some time after removing from the heat , unlike the leaded sample. Maybe
acting on the 5 percent silver content.


--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://diverse.4mg.com/index.htm



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