Here’s a recipe for 1 liter of Lugol’s old fashioned strength 15% (used may 2012):
- 1000 ml dark glass container with cap that can resist Iodine vapour.
- 50 grams I2
- 130 grams KI (equals 100 grams I-)
- Wooden/plastic/glass stirrer
- 1 liter (= 1 quart) of distilled water (I use tab water, but then we have very good tap water in Holland)
This is what you do:
Fill a plastic/glass container with 1/4 liter of warm distilled water (I2 dissolves best in a high concentration of I-). Use warm water because adding and dissolving the KI will cool the water down considerably, lessening its (KI’s) ability to dissolve. Add the KI. Stirr / swirl until dissolved. Move this to a glass container (on account of staining) and add the I2. Be careful if the water is still warm: I2 will evaporate and irritate your mucous membranes and eyes! Stirr / swirl until dissolved. Put (or make) this solution into the dark glass container. Then add distilled water until 1 liter is reached.