Back in 1875 Father Secchi published his "Le Soleil". This was an up-to-date review of solar observing and solar knowledge.
He mentions, in Volume 1 his visual observations of sunspots.
He was convinced that he had seen the umbra of some sunspots covered by a faint pink veil of light. He includes many etchings of this phenomenon.
Notwithstanding his observations, this "pink veil" has not been recorded in modern times.
https://collection.crystalbridges.or...d-veiled-spots
A challenge to modern observers????