U of S | Mailing List Archive | alt-photo-process-l | Re: humidity and gum coating

Re: humidity and gum coating

What kind of sizing did you use?  I'm no gum expert, but I would think
that paper sized with a hardener as opposed to gelatin alone wouldn't try
to soak the pigment in.  My experiences with gluteraldahide seemed to
completely isolate the emulsion from the rest of the paper.  Just a

Camden Hardy


On Sat, September 2, 2006 10:12 pm, Judy Seigel wrote:
> On Sun, 3 Sep 2006, Tom Sobota wrote:
>> As to why some papers develop spots when coated wet, that's a good
>> question,
>> I haven't the slighest idea. Differences in surface porosity come to
>> mind,
>> but these papers have been double-coated with gelatin and hardened ...
> For the sake of "experiment," I tried coating the gum emulsion on
> pre-wet paper a couple of times a while back, and found some spotting, but
> mostly staining. Serious staining.  I theorize that even though the
> surface was blotted off, the interior remained wet and that the emulsion
> soaked down & settled in there -- in other words, got tangled into the
> paper fibers, as it doesn't when it just sits on the gelatin-sized
> surface.
> I gather the reason for coating wet in the 1st place is to get an even
> coat.  IME, coating with a fairly wide foam applicator (the kind with the
> wood handle that has been very slightly dampened & then blotted dry) and
> NOT NOT NOT hake brush, spreading swiftly and THEN smoothing with dry
> hake, solves any problem with coating.
> It's important however to move across the surface quickly, meaning in wide
> free strokes. Trying to "smooth" as you go (instead of later) slows you
> down, and (I find) by the time you get across, it's started to get tacky &
> stripe-y where one stroke passes the next. In other words, the risk of
> streaks is with the initial dispersal. Once that's done, you can "buff" at
> relative leisure.
> However, this works best with a relatively thin emulsion, at the very
> least equal parts am di solution & gum...
> Judy