Rejuvenating Dry SLA batteries

I had some dead 12v 12Ah batteries from an APC smart ups 1000 that were quite old (md 2009) and very dry. I have replaced them with a set of new 18Ah batteries. I thought I would try my hand at getting these old batteries going again.

One battery was showing ~12 volts but could draw no current what so ever and the other was shown only ~10 volts

Prep: caps off, 10ml syringe and a 22g drawing up needle
Pretty thirsty for two batteries
Initially charging at 14.7v/40mA per battery then pulling charge down to 14.4v/35mA per battery for the main charge cycle.

charging at 15.5 in a desulfication phase