I have also observed this phenomenon in the past.
> Thicker papers such as Crains Busness Card Stock (such as that from B&S)
> or Arches Platine seem to require longer clearing and washing times. In
> the past, I had to clear for up to an hour. Because of deteriation of
> image quality, I experimented and found that a water wash prior to
> clearing reduced clearing times by more than half. Also with some
> papers such as Arches Platine, some time in hypo remover or equivilent
> chemical after the acid helps complete the clearing in less time.
Arches Platine seems to be a very stubborn paper to clear with most
"traditional" clearing baths including acids and strait EDTA. I've
found that it clears very readily in 2 or 3 baths of either Kodak
Hypo-clear (preceded by a water wash as Jeffrey suggests) or a
home-made version of hypo-clear consisting of approximately one Tbsp
of EDTA (tetra) and one Tbsp of sodium sulfite per liter of water.
The pre-clearing wash step greatly increases the capacity of the
clearing bath. Since using this cleaing bath for Platine, I've
found that it works equally well on every paper I've tried including
Cranes Bus. Card stock (aka Platinotype), Cranes Parchmont wove,
Cranes distaff linen, Simili Japon, Bienfang 360, etc. In each case,
the papers seemed to clear faster than EDTA by itself.
After approximately 10 minutes of clearing and rinsing, I wash in an
archival washer for 15 to 20 minutes.
Kerik Kouklis
http://members.aol.com/kerik717/