Supposedly there are a handful of old style, silver rich films available. Efke R100 is said to be one of 'em. Can't tell by the film base which is so thin and conspires to curl so fiercely one would be disinclined to associate the words "thick" or "rich" with the film. The word I associate with R100 is "Behave, DAMMIT!"
OTOH, it is truly a lovely film.
On the third hand so is APX 100 and I haven't heard whether it's supposed to be silver rich, oil rich, nuevo riche or land poor.