Every time I gather a new plant, I brew a tea of it in three jars. I modify the pH of two of the jars resulting in:
Jar 1 = acidic (low pH)
Jar 2 = neutral (7)
Jar 3 = basic (high pH)
Then I add a bundle of three strings to each jar.
String 1 = Iron (long string/2 knots)
String 2 = Alum (medium string/1 knot)
String 3 = No mordant (short string/ no knot)
The knots or string lengths help me keep track of which string has which mordant.
When I have a bundle of three strings in each of the three jars, I keep the pot on simmer while I make some tasty tea and drink up some phytochemicals.