Over the past 7 months I have been testing several different collodion formulas. This is the first set.
This is Lea Formula 3 – Portrait collodion, from “Manual of Photography” by M. Carey Lea
It is a slow ripening Cadmium based formula.
At one day it is unusable.
At 2 months it’s almost usable.
At 5 months it’s nice.
At 7 months it’s nice and maybe a bit faster.
The advantage of this formula is that once ripened it’s extremely stable. It is said to last for 12 to 18 months or more.
Disadvantage – It’s cadmium based and it takes 5 months to ripen.
I have made a lithium based version of this formula that hopefully will ripen slightly faster and last as long.
At 7 months you can see that Lea Formula 3 is still a nice yellow color. A hybrid using LiBr in place of CdBr2 is aging faster.