I have had 3 times lacquered krises in my possession and I have had great results with boiling water. In fact I boiled the whole kris (blade alone obviously!) in salty water (it increases the boiling point temperature). It takes only few minutes and you see small bubbles forming under the lacquer. A soft brush (old toothbrush) removes the lacquer.
I spoke about this in a thread I created
http://www.vikingsword.com/vb/showthread.php?t=28617