After the fact is only good if they were not aware of the חציצה (interpose) on their hand before they went to wash.

What is the halacha if one has a mark on their hand that they could only see but they are unable to feel it, and creams and oils on ones hands when going to wash for bread.

How to work with marks on ones hand when the marks on their hand are from the type of job that they do. (e.g. a painter, a construction worker, etc.)

CHATZITZA (interpose) A SCAB on ones skin.

What is the halacha if person is מקפיד (particular) on a certain thing but everybody else is not particular (CHATZITZA or not)

Cuticles (hanging pieces of dead skin) around the nail area, was it a חציצה (interpose) or not. For a splinter we go after the general public in reference to a CHATZITZA interpose.

What is considered a CHATZITZA (interpose) in reference to ones fingernails.

When one finds a חציצה (interpose or partition) after they washed for bread and one should check their hands before washing.

When one has to rewash in the middle of the meal the same halachas would apply as far as the mechanics go.

Small amounts of dirt, fruit juice, nail polish, etc. - chatzitza (חציצה) or not.