[pure-silver] Re: Dry Mounting REALLY permanent?
- From: "Richard Knoppow" <dickburk@xxxxxxxxxxxxx>
- To: <pure-silver@xxxxxxxxxxxxx>
- Date: Thu, 14 Oct 2010 19:06:59 -0700
----- Original Message -----
From: "Tom Schofield" <tomschofield@xxxxxxxxxxx>
To: <pure-silver@xxxxxxxxxxxxx>
Sent: Thursday, October 14, 2010 3:04 PM
Subject: [pure-silver] Re: Dry Mounting REALLY permanent?
I was taught to preheat the mat board by putting it in the
press before mounting it.
I suspect that mounting in the Ansel Adams tradition used
higher temp tissue with the fiber based paper. Maybe the
problems are more endemic to the lower temp tissues, but I
do not consider myself an expert!
Tom
Please see my post, _all_ components except the
mounting tissue need to be dryed out in the press before
mounting. The release tissue does not need to be dryed since
it is non-absorbent but is used over the emulsion side of
the print to _prevent_ the gelatin from drying out too much.
The main reason prints and films curl is the differential
shrinkage of the emulsion and support. The emulsion tends to
expand when moist and shrink when dry. The support also
changes size somewhat but not nearly as much as the gelatin.
By drying with release tissue in contact with the emulsion
side and absorbent paper in contact with the support the
moisture in the two is equalized so that the curl is
minimized. The mounting boards do not tend to curl so much
and probably do not really need drying out in the press but
it does not hurt them.
Properly dry mounted prints will still tend to curl
under extreme moisture conditions but not as much as prints
mounted by other methods and the prints will not separate
from the mount. Of course one can mount on very stiff
material so that there is no curl at all.
If humidity is a serious problem the prints can be
coated with a protective lacquer. Kodak used to make a
special lacquer but I think Krylon Archival Varnish will
work and can be removed. It also has a UV filter in it.
--
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx
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