1. Taking the test paper into the fathomable liquor for a half of second later, then take it out and compare with standard colorful ribbon, namely is PH value
2. This test paper is mot applicable for the assuasive liquor and the acid or alkali liquor that the concentration is under 0.01%
3. This test paper need to be kept in the shade and dry location.
Preservation period is 3 years.