The block survived the bite. There is still lots of lino left. It seems that extended biting times do not make a big difference: there's be a point at which the soda runs out of power. Need to find out where this point is.
The brown marks on this print are made by the wet clay of the lino. I didn't clean or dry the block thoroughly enough before printing!
(Update: Four weeks later, I stuck this print in my sketchbook. The brown marks had not dried, and transferred onto the facing page.)