Here's some recap of what we already know (copy paste of ffxiclopedia):
* Stores MP while reducing HP. The effect ends once the MP limit is reached, HP is too low, or you are attacked. Stored MP is gained when the ability is reactivated.
* Obtained: Scholar Level 35
* Recast Time: 30 seconds
* Duration (Charging): Until MP limit is met
* Duration (Charged): 2 hours
* Your character’s HP will slowly decrease while storing MP and you will be unable to enter healing mode or log out while this ability is in effect.
* The MP limit is 25% of your max HP (before applying "Converts HP -> MP gear").
* This effect persists when changing zones.
* Enhanced by Scholar's Mortarboard.
* Refresh effects from food or the Red Mage spell will not take effect while Sublimation is charging.
So now to the experimental stuff:
We all know that Sublimation is ticking away at 2hp/tick till it drained 25% of your max hp. This is actually only half the truth.
While Sublimation is charging ANY physical damage you take counts toward the 25% hp for Sublimation.
But the MP restored is 25% of your current HP, not your max HP.
I happend to notice that when i just applied a fresh Sublimation, and gravity wore off at the wrong time and i took quite the beating, and after less than 20 seconds my Sublimation was charged full. Cured me to full and used it and got the full effect.