Lichen — Chemical spot tests

K — Potassium hydroxide

Safety: Caustic. Avoid getting on skin, in the eyes, mouth, etc.

Disposal: Neutralize with an acid, and pour down the sink with plenty of water. [2]

C — Sodium hypochlorite (bleach)

Safety: Caustic.

Purchase: While you can use normal household bleach, some people suggest buying Milton Sterilizing Fluid, since it doesn't contain ions (such as potassium) which could give false negatives.

Disposal: Since I bought Milton Sterilizing tablets, not fluid, those can probably be discarded in the trash.

I — Iodine

Purchase: In the form called "Lugol’s iodine".

P — Para-phenylenediamine

Safety: Mutagenic, allergenic, and may be carcinogenic. Avoid inhaling or contact with skin. Great care should be exercised when using it.

Disposal: ??? This, maybe? See also, this Google query.

References

• https://britishlichensociety.org.uk/learning/chemical-tests
• https://en.wikipedia.org/wiki/Spot_test_(lichen)
• https://www.inaturalist.nz/posts/123367-practical-introduction-to-chemical-tests-of-lichens
• Photos at https://www.sharnoffphotos.com/lichensNH/lichen_tests.html
• https://northwest-lichenologists.wildapricot.org/Tools-and-chemicals
• http://blogs.evergreen.edu/lichens/studying-lichens/
• https://pressbooks.openeducationalberta.ca/albertalichens/chapter/chemistry/

YouTube:

• https://www.youtube.com/watch?v=ND6WjrKioCY
• https://www.youtube.com/watch?v=dSbXvrh4_8A