Moshohoritou, R. published the artcileThe effect of some additives on the throwing power and stability of tin(II) solutions during A.C. Coloring of anodized aluminum. Part I: Heterocyclic organic compounds, Computed Properties of 636-73-7, the publication is Plating and Surface Finishing (1994), 81(1), 60-4, database is CAplus.
Nicotinic acid, piperidine-4-carboxylic acid, imidazole, 2-picolinic acid, 3-pyridinesulfonic acid, piperazine and piperidine were used as additives in electrolytic coloring of anodized aluminum from tin(II) solutions Their influence on the throwing power and their resistance to atm. oxidation were studied.
Plating and Surface Finishing published new progress about 636-73-7. 636-73-7 belongs to pyridine-derivatives, auxiliary class Pyridine,Sulfonic acid, name is Pyridine-3-sulfonic acid, and the molecular formula is C5H5NO3S, Computed Properties of 636-73-7.
Referemce:
https://en.wikipedia.org/wiki/Pyridine,
Pyridine | C5H5N – PubChem