IF THE CLOSUP OF THE MANDAU IS OF THE BLADE IT WOULD APPEAR TO BE A PEACE OF MONO STEEL THAT HAD BEEN SOAKED IN ACID TO APPEAR OLD. A MORE COMPLETE PICTURE OF THE BLADE WOULD REVEAL MORE. THE DAYAK AND OTHERS MAKE GOOD BLADES FOR THOSE THEY ACTUALLY USE . FOR TOURIST SOUVINEERS THEY OFTEN USE ANY OLD PIECE OF METAL AND SOMETIMES THEY DON'T EVEN QUALIFY AS A USABLE BLADE OR HAVE A PROPER EDGE. I HAVE SEEN VERY WELL MADE BLADES AS WELL AS PIECES OF SCRAP METAL SUBJECTED TO THIS DESTRUCTIVE ACID BATH AND HEARD THE STORIES OF HOW OLD IT IS OR THAT IT WAS USED IN CEREMONIAL FUNCTIONS OR THAT THE SHAMAN USED THE RESULTING BLACK RUST FOR MEDICINE.

I DON'T SEE WHY THEY BOTHER AS IT DETRACTS MORE FROM THE OBJECT THAN IT ADDS AND MAKES IT MUCH LESS ATTRACTIVE.