Here's some short answers:
Mercerized cotton has a higher luster, greater strength, holds more dye, and does not shrink as much when washed as unmercerized cotton.
Mercerized Cotton is prepared using a process first discovered by John Mercer in 1844. He found that when cotton fibres are submersed in a strong caustic soda solution they swell and develop a high lustre. Because of this, Mercerized Cotton fibres dye to a more brilliant shade than un-mercerized cotton, are stronger and more lustrous.
Here's the long answer..it's actually quite interesting..at least for a nerd. :roflhard:
I googled it. :rollseyes: