It would be most helpful if you posted just which Sargent's work you refer to .
I was not aware he did water color , but
given that,,,, I am sure his style changed little .
If you look closely at his oils you tend to see that his focal Point seemed to become the center of the painting.
Mostly the face of the subject.
From there he seemed to gravitate outward in almost a cyclical motion becoming looser and looser with brush strokes as he moved farther out
Lady Elenor and the Hotel Room should give you some insight to this method .
For the most part Sargent was not wot one could call a Experment Artist of any kind
He had super Social skills and worked among the Rich and Famous people of that time frame .
Thus to say he almost never did any works of the downtrod ( he knew where his bread was buttered from) ha
But if you wish to learn about any great painter Sargent would certianly be a good choice
He was a master at half tones , lights and darks .
