Van Dykes

Hello all. Anyone here working in Van Dyke? I am mostly set but need to make some 8x10's for contact prints until I learn how to make digital negs where I can use my vast 4x5 library. I have the juice for it from Freestyle and paper. One question I have is approximately how long will a properly processed Van Dyke print last before starting to fade due to not toning with gold or Plt? Of course this means a properly processed and washed print. Any suggestions would be welcomed. jjames100