Medieval Red Analysis


CHEMICAL ANALYSIS of Medieval Striated Red Glass[1]

Lawrence Saint was given a piece of medieval red glass containing a bubble which clearly separated the streaky red flashed layer from the clear greenish base glass. Chemical analysis of both the red & green portions of the glass was commissioned by Saint and performed by the chemist Fredrick Wynkoop.


Red Portion
Green Portion
Silica (sand)
52.26%
52.67%
Alumina
3.86%
3.20%
Ferric Oxide (Iron)
.27%
.46%
Calcium Oxide (Lime)
16.16%
16.55%
Magnesium Oxide
5.31%
5.43%
Titanic Oxide (titanium)
.20%
.20%
Manganese Oxide
1.00%
1.02%
Sodium Oxide (Soda)
.90%
.92%
Potassium Oxide (Potash)
15.27%
15.06%
Phosphoric Anhydride (P2O5) (Bone Ash)
4.31%
4.44%
Cuprous Oxide (Cu2O) (Copper)
.26%
None
Tin
.16%
None



[1] The Romance of Stained Glass by Lawrence Saint pg 40