(Part 2) Tests for PbF / SnPb solder
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From: N_Cook on 5 Apr 2010 07:14 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
From: N_Cook on 5 Apr 2010 11:29 Just checked a day later and the SnPb boiled in vinegar for 20 seconds plus potassium iodide shows a slight yellow colour compared to the PbF sample. What other non-license source of a strong acid other than car battery acid? drain cleaner is clobbered by elfin safety these days.
From: Wild_Bill on 6 Apr 2010 01:20 Citric acid should be widely available, and you might want to try phosphoric acid if you can find a source for a small amount. Phosphoric acid is used in foods, but also as a diluted solution to etch and clean metals before applying paints or other corrosion-preventive coatings. Most autobody repair/refinishing shops will be familiar with diluted phosphoric acid as a preparatory step in applying primer to steel or aluminum (aluminium?) parts. A typical generic term here in the US is "metal prep". A paint distribuor should have a way to get diluted PA for you, but you may have to buy a quart (1L sized bottle). Diluted PA isn't particularly dangerous to handle, but it stings if it gets into a cut in the skin, avoid any conact with eyes. I don't know if either of these acids would be useful for detecting lead, or lead-free solders. -- Cheers, WB .............. "N_Cook" <diverse(a)tcp.co.uk> wrote in message news:hpcviv$bl3$1(a)news.eternal-september.org... > Just checked a day later and the SnPb boiled in vinegar for 20 seconds > plus > potassium iodide shows a slight yellow colour compared to the PbF sample. > What other non-license source of a strong acid other than car battery > acid? > drain cleaner is clobbered by elfin safety these days. > >
From: N_Cook on 6 Apr 2010 03:18 Wild_Bill <wb_wildbill(a)XSPAMyahoo.com> wrote in message news:nwzun.345696$Hq1.316805(a)en-nntp-04.dc1.easynews.com... > Citric acid should be widely available, and you might want to try phosphoric > acid if you can find a source for a small amount. Phosphoric acid is used in > foods, but also as a diluted solution to etch and clean metals before > applying paints or other corrosion-preventive coatings. Most autobody > repair/refinishing shops will be familiar with diluted phosphoric acid as a > preparatory step in applying primer to steel or aluminum (aluminium?) parts. > A typical generic term here in the US is "metal prep". A paint distribuor > should have a way to get diluted PA for you, but you may have to buy a quart > (1L sized bottle). > > Diluted PA isn't particularly dangerous to handle, but it stings if it gets > into a cut in the skin, avoid any conact with eyes. > > I don't know if either of these acids would be useful for detecting lead, or > lead-free solders. > > -- > Cheers, > WB > ............. > > > > "N_Cook" <diverse(a)tcp.co.uk> wrote in message > news:hpcviv$bl3$1(a)news.eternal-september.org... > > Just checked a day later and the SnPb boiled in vinegar for 20 seconds > > plus > > potassium iodide shows a slight yellow colour compared to the PbF sample. > > What other non-license source of a strong acid other than car battery > > acid? > > drain cleaner is clobbered by elfin safety these days. > > > > > 2 days on and a more definite but pale yellow colouration , after shaking, so a precipitate. Tin heavy sample still clear liquid. Perhaps it is just picking up lead carbonate or something as contaminant on the surface, but old SnPb is likely to be the only such to be found in the UK these days. Will try boiling for 10 minutes in vinegar , i doubt you can grind down solder in a mortar and pestle (another test maybe, perhaps high tin solder will so grind down and not leaded version). Will try getting phosphoric acid . Isn't there formic acid for de-calcifying or something ? The problem trying to get around is not post 2006 boards with PbF on the overlay and green stickers on the casing but identifying boards like Yamaha from 2001 or Marshall from 2003 but with PbF soldering -- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on http://diverse.4mg.com/index.htm
From: N_Cook on 6 Apr 2010 12:06
Wild_Bill <wb_wildbill(a)XSPAMyahoo.com> wrote in message news:nwzun.345696$Hq1.316805(a)en-nntp-04.dc1.easynews.com... > Citric acid should be widely available, and you might want to try phosphoric > acid if you can find a source for a small amount. Phosphoric acid is used in > foods, but also as a diluted solution to etch and clean metals before > applying paints or other corrosion-preventive coatings. Most autobody > repair/refinishing shops will be familiar with diluted phosphoric acid as a > preparatory step in applying primer to steel or aluminum (aluminium?) parts. > A typical generic term here in the US is "metal prep". A paint distribuor > should have a way to get diluted PA for you, but you may have to buy a quart > (1L sized bottle). > > Diluted PA isn't particularly dangerous to handle, but it stings if it gets > into a cut in the skin, avoid any conact with eyes. > > I don't know if either of these acids would be useful for detecting lead, or > lead-free solders. > > -- > Cheers, > WB > ............. > > > > "N_Cook" <diverse(a)tcp.co.uk> wrote in message > news:hpcviv$bl3$1(a)news.eternal-september.org... > > Just checked a day later and the SnPb boiled in vinegar for 20 seconds > > plus > > potassium iodide shows a slight yellow colour compared to the PbF sample. > > What other non-license source of a strong acid other than car battery > > acid? > > drain cleaner is clobbered by elfin safety these days. > > > > > The PA I found as rust remover (hardware and car spares shops) probably has dye/colour change stuff in it, so defeating the purpose here |