Red Litmus Indicators or Litmus Paper is most used in chemical laboratory in Bangladesh. Basically used in School, College, University Laboratory.
Red Litmus is a water-soluble mixture of different dyes extracted from lichen. Dyeing filter paper either red or blue with this ink creates one of the oldest forms of testing alkalinity and acidity. Red litmus paper turns blue under alkaline conditions. Sold in boxes of 100 strips of paper. Made in India.