LEAD

Miscellaneous

Family: None
Region: None
Mined At: Unspecified
Raw Mineral: Yes
Generic: No

Notes

(Richard Willis)

Element, with the symbol Pb and atomic weight of 207.21
A powerful flux, lead fuses from 500 to 1200ºC. At 1200+ it burns off in conversion to gas.
Popularly used in fritted forms (for safety and convenience), of boron and/or aluminum, silicon, sodium, potassium, calcium, etc.
A simple test for a lead’s solubility (ergo its toxic presence) in a fired glaze is the following: Put a few drops of nitric acid on the glaze, heat until dry, then wash off with a few drops of distilled water into a test tube. To the solution in the test tube add a couple of drops of potassium iodide and let sit. If within a few minutes a precipitate (of lead iodide) begins forming it is evident that sufficient soluble lead is on or near enough to the surface to be toxic in that mild acids (tea, citri c juices, coffee, etc.) can pick it up and carry it into the stomach where it will accumulate. see “Thorpe’s Rule” for safe lead under Appendix III
water solubility & fusion ºC
— litharge — insoluble — 835
— minium — insoluble — 850
— carbonate — insoluble — discomposes
— chromate — soluble in hot water — 844
commonly used forms
— oxide (yellow-orange – “litharge”) PbO— carbonate (white — “ceruse”) 2 PbCO₃, Pb(OH)₂— chromate PbCrO₄— dioxide PbO₂— sulfur PbS
— minium (red, “heavy”)) Pb₃O₄— nitrate Pb(NO₃)₂— bi-silicate (“Leach frit”) PbO, 2SiO₂“safe” crude lead glaze compositions 1080º-1200ºC
— K₂O 0.05, Na₂O 0.05, CaO 0.1, Al₂O₃0.1, PbO 0.9, SiO₂1.5
— K₂O 0.025, Na₂O 0.025, CaO 0.1, Al₂O₃0.1, PbO 0.85, SiO₂1.2
— K₂O 0.05, Na₂O 0.05, Al₂O₃0.17, PbO 0.8, SiO₂1.35
— K₂O 0.025, Na₂O 0.025, CaO 0.15, Al₂O₃0.15, PbO 0.8, SiO₂1.4
— K₂O 0.075, Na₂O 0.075, CaO 0.2, Al₂O₃0.2, PbO 0.65, SiO₂1.2
— K₂O 0.05, Na₂O 0.05, CaO 0.3, Al₂O₃0.2, PbO 0.6, SiO₂1.6
— K₂O 0.05, Na₂O 0.05, CaO 0.15, ZnO 0.15, Al₂O₃0.15, PbO 0.6, SiO₂1.5
— K₂O 0.085, Na₂O 0.085, CaO 0.08, BaO 0.25, Al₂O₃0.33, PbO 0.5, SiO₂2.0
— K₂O 0.1, Na₂O 0.1, CaO 0.3, ZnO 0.15, Al₂O₃0.25, PbO 0.35, SiO₂1.75
— CaO 0.3, ZnO 0.2, Al₂O₃0.2, PbO 0.5, SiO₂1.6
— CaO 0.3, BaO 0.3, Al₂O₃0.3, PbO 0.4, SiO₂1.6
NOTE: Since barium and lead are equally toxic, great caution must be taken when handling the two while crude at the same time.

Authors

Richard Willis (Owner)

XML

<?xml version="1.0" encoding="UTF-8"?>
<material name="LEAD" descrip="" generic="0" rawmineral="1" searchkey="" loi="0.00">
<notes>
<note>Element, with the symbol Pb and atomic weight of 207.21 
A powerful flux, lead fuses from 500 to 1200&ordm;C. At 1200+ it burns off in conversion to gas. 
Popularly used in fritted forms (for safety and convenience), of boron and/or aluminum, silicon, sodium, potassium, calcium, etc. 
A simple test for a lead&#146;s solubility (ergo its toxic presence) in a fired glaze is the following: Put a few drops of nitric acid on the glaze, heat until dry, then wash off with a few drops of distilled water into a test tube. To the solution in the test tube add a couple of drops of potassium iodide and let sit. If within a few minutes a precipitate (of lead iodide) begins forming it is evident that sufficient soluble lead is on or near enough to the surface to be toxic in that mild acids (tea, citri
c juices, coffee, etc.) can pick it up and carry it into the stomach where it will accumulate. see &#147;Thorpe&#146;s Rule&#148; for safe lead under Appendix III 
water solubility &amp; fusion &ordm;C 
&#151; litharge &#151; insoluble &#151; 835 
&#151; minium &#151; insoluble &#151; 850 
&#151; carbonate &#151; insoluble &#151; discomposes 
&#151; chromate &#151; soluble in hot water &#151; 844 
commonly used forms 
&#151; oxide (yellow-orange &#150; &#147;litharge&#148;) PbO 
&#151; carbonate (white &#151; &#147;ceruse&#148;) 2 PbCO3, Pb(OH)2 
&#151; chromate PbCrO4 
&#151; dioxide PbO2 
&#151; sulfur PbS 
&#151; minium (red, &#147;heavy&#148;)) Pb3O4 
&#151; nitrate Pb(NO3)2 
&#151; bi-silicate (&#147;Leach frit&#148;) PbO, 2SiO2 
&#147;safe&#148; crude lead glaze compositions 1080&ordm;-1200&ordm;C 
&#151; K2O 0.05, Na2O 0.05, CaO 0.1, Al2O3 0.1, PbO 0.9, SiO2 1.5 
&#151; K2O 0.025, Na2O 0.025, CaO 0.1, Al2O3 0.1, PbO 0.85, SiO2 1.2 
&#151; K2O 0.05, Na2O 0.05, Al2O3 0.17, PbO 0.8, SiO2 1.35 
&#151; K2O 0.025, Na2O 0.025, CaO 0.15, Al2O3 0.15, PbO 0.8, SiO2 1.4 
&#151; K2O 0.075, Na2O 0.075, CaO 0.2, Al2O3 0.2, PbO 0.65, SiO2 1.2 
&#151; K2O 0.05, Na2O 0.05, CaO 0.3, Al2O3 0.2, PbO 0.6, SiO2 1.6 
&#151; K2O 0.05, Na2O 0.05, CaO 0.15, ZnO 0.15, Al2O3 0.15, PbO 0.6, SiO2 1.5 
&#151; K2O 0.085, Na2O 0.085, CaO 0.08, BaO 0.25, Al2O3 0.33, PbO 0.5, SiO2 2.0 
&#151; K2O 0.1, Na2O 0.1, CaO 0.3, ZnO 0.15, Al2O3 0.25, PbO 0.35, SiO2 1.75 
&#151; CaO 0.3, ZnO 0.2, Al2O3 0.2, PbO 0.5, SiO2 1.6 
&#151; CaO 0.3, BaO 0.3, Al2O3 0.3, PbO 0.4, SiO2 1.6 
NOTE: Since barium and lead are equally toxic, great caution must be taken when handling the two while crude at the same time. 

</note>
</notes>
</material>

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LEAD

Miscellaneous

Notes

(Richard Willis)

Authors

XML