It is the only pyrogallol tannin which does not deposit bloom, or ellagic acid, on the leather.
Tanning materials are divided into two main classes: pyrogallol, Catechol.
Table 10 shows the relation between temperature and intensity of luminescence with pyrogallol and various oxidizers.
Sumach is the other pyrogallol tan of commercial importance.
It is particularly advantageous to blend judiciously the two main types of material, the pyrogallol and catechol tans.
This is especially well seen in the action of various oxidizers on pyrogallol and H2O2 recorded in Table 10.
Newton employs it in combination with pyrogallol and soda in the development of bromo-gelatine plates.
Thus the "maximum luminescence pressure" of pyrogallol increases with increase of temperature.
Solutions of pyrogallol tans all give a blue-black colour with a dilute solution of ferric alum.
They are all, however, derived from either catechol or pyrogallol, and yield these substances if carefully heated to about 200 C.
pyrogallol py·ro·gal·lol (pī'rō-gāl'ôl', -ōl', -gô'lôl', -lōl')
A white, toxic crystalline phenol used as a photographic developer and to treat certain skin diseases. Also called pyrogallic acid.