Seems to me I read somewhere recently that the amount of Borax in B should be 10g/L or maybe a little more.(posted 8341 days ago)Another formula:
A:
1L water, 3g metol, 50g sodium sulfite
B:
1L water, 5g borax, 50g sodium sulfite.
Five minutes in each, as a starting point. For more contrast give more time in A.
I have no idea how well that formula works.