Blue Slips for Wood Firing

I tried 2 new blue slip recipes, as my previous experiments were not blue enough.

Blue Slip 1:
60 Hymod AT
20 Potash Feldspar
10 Talcum
10 Flint
2 Cobalt Carbonate
2 Copper Carbonate

Blue Slip 2:
60 Hyplas 71
20 Potash Feldspar
20 Silica
0,5 Cobalt Carbonate
2 Iron Oxide

Lessons learned:

Iron Oxide is not really helpful as it tends to oxidize back to brown if reduction is not strong enough.
Cobalt Carbonate can cause black areas, eventually only if applied too thin.
Salt preserves the blue color during cooling, but also results in higher glaze flow.