Not hydroscopic? Huumm- must be the difference between American / Limey wording-- In the welding trade, we have a SMAW electrode that must be kept in a warm over/dryer before use, as its flux is hydroscopic in nature- it can absorb water from the air/environment- The AWS code for it is 7018- also found in higher tensile ranges as 9018-etc. Lincoln number is LH-70.. We in the trade commonly call it "Lo-Hi"-- RWTF

"The field is the touchstone of the man"..