Blue litmus and red litmus papers facilitate a general test for acid or alkaline reaction. The change occurs around pH 5 to 8. They are particularly recommended for educational use.

• Red litmus paper turns blue in alkaline solutions
• Blue litmus paper turns red in acidic solutions
• Inexpensive
• Convenient and portable for field use

Indicator books are particularly suitable for educational and industrial use. In schools this format is economical because the amount of paper per student can be carefully controlled.

Indicator books are particularly suitable for educational and industrial use. In schools this format is economical because the amount of paper per student can be carefully controlled.