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by Chris A. Paschke, CPF GCF CMG
"TTPM
- Temperature"
February 1995
Though it is human
nature to place blame on almost everything else before we point the finger at
ourselves...it is indeed, frequently operator error that triggers most
unsuccessful mountings. Last month I
said that understanding the elements of time, temperature, pressure and
moisture (TTPM) will ensure predictable mounting success. I'm not about to tell you there are no
mechanical failures, there are. But they
are rare in relation to the stories I've heard about mounting the wrong side of
a newspaper clipping, air bubbles as a result of lack of pre-drying, or shall
we just turn to "Nightmare On Frame Street".
Predictability
should be the hallmark of dry mounting.
When repeatedly mounting similar items, the results should be notably
similar every time. If your mounted results
are less then they ought to be, it can usually be tracked back to one of the
key elements.
WET AND SPRAY
MOUNTING
Temperature is
perhaps the only element that most directly relates to heat dry mounting. Most wet and spray glues give directions suggesting
recommended storage and preferred room temperatures when mounting. Often they state "for best
results...", reinforcing the importance of proper temperatures even with
wet glue and sprays.
Freezing winter
temperatures restrict shipping of many wet glues and temperatures of below 60F
are generally undesirable for most any liquid based adhesive. Excessive cold tends to stiffen and somewhat
solidify them or encourage them to clump and/or separate.
DRY MOUNTING
Since suggested
mounting temperatures for dry mount adhesives and films range everywhere from
150F to 225F, it is impossible to give the ideal single temperature setting to
be used in every situation. The best I
can do is try to establish a median or average safe daily temperature that will
meet most normal mounting project requirements.
By establishing an
average base temperature for as much mounting as possible, idle time waiting
for a press to heat up or cool down is minimized. Thus loss of any productive mounting time
will be nearly eliminated. Seal Products
suggests their mechanical press be set 10 degrees cooler than a hot vacuum
press, but I've always set both presses at the same 180F. If a number of individuals are regularly
using all of the equipment, it removes confusion to maintain the same base
temperature on both your mechanical and vacuum presses. Both of my presses remain set at 180F for
most daily routine projects.
New digital and
preprogrammed equipment already carry manufacturer's settings for different
types of mounting needs. All you need do
is punch in the corresponding program to the mounting you will be doing. The time and temperature will automatically
kick in.
STANDARD
TIME/TEMPERATURE RATIOS
When using a
mechanical press, set at 180F, an 8x10" print requires about 1 minute of
mounting time while an 18x24" requires about 3 minutes. It will also take about a minute for the
predrying process in both of these instances, increasing the approximate
mounting time to 2 minutes and 4 minutes respectively.
In a vacuum press,
the same 180F will mount either the 8x10" or 18x24" print in about 4
minutes. The physical action of pulling
a vacuum will take most of the first minute allowing the remaining 3 minutes
for the actual mounting time needed to heat all materials to the required
bonding temperature.
"If it takes
4 minutes to mount at 180F can't I mount the same item for 2 minutes at 200F,
allowing me to mount twice as many pieces in the same amount of time?", is
a good question. Perhaps in theory this
appears correct, but take into consideration having to more closely monitor
each project to avoid damage. Now you
end up wasting time. Plus, often the one
project you could ruin by excessive heat will be the bear you can't replace!
HOW TO GET WHAT
YOU WANT
Damage may be
defined in many ways. It could simply be
a mounting result different from what you might have expected, or what you
thought was your desired end product. Individual tissues and pure adhesive
films may vary, depending upon the item being mounted, it's thickness or
delicacy, it's substrate and the amount of adhesive saturation you wish to
achieve.
A 16x20"
piece of delicate rice paper with dominant visible silk fibers is to be mounted
onto a dark mat board encouraging color tinting for
use as a designer mat (see "Color Tinting" September 1994). By using pure adhesive film to guarantee the
visibility of the silk fibers by contrasting them against the darker mat board
backing, the adhesive's recommended temperature of 180F for 2-3 minutes (TTPM)
may need to be increased to 200F for as long as 15-30 minutes, encouraging
saturation.
The longer the
rice paper remains under heated pressure (TTPM), at the chosen temperature, the
more it will absorb the film adhesive and become more transparent (see
"Ghosting Newsprint", November 1991).
Since posters or
paper graphics (non-limited editions) often make up a major portion of daily
mountings, using rolled tissue adhesive (i.e.: ColorMount, TriMount or TM2) in
a press set at 180F would be a reasonable selection, a good 80% adhesive. For routine mountings, always extend the time
in a press rather than increasing the temperature to accommodate substrate
thickness and larger size variations.
RAISING
TEMPERATURES FOR CREATIVITY
Multiple 4-ply rag
boards with layers of art paper and adhesive between for pin-striped tiered
mats may require more aggressive techniques and adhesives. Longer dwell times and higher temperatures
often accompany the creation of 8, 12, or 16ply mat boards. Remember the entire mounting package must
reach the required temperature in order to begin the bonding process. A denser substrate or multiple layering will
always take longer even if the temperature has been increased. These are among the exceptions to standard
dry mounting rules.
Wrapping mats and
foam in a press is quick, permanent and profitable. All foam boards will compress slightly around
the outer edges when placed in any heat press, it's the nature of the beast and
will not do damage to the inner mounting.
Foam boards will, however, actually begin to melt once they reach an
interior temperature of 230F. If your
press is set at 200F and your foam is internally melting (not simply
compressing around the outer edges), check your thermostat with indicator
strips for temperature accuracy.
PHOTO FEAR
Photographs
require some care, and extremes of temperature for long durations should be
avoided, but you need not be afraid of the mounting process. Watch the time factor! Leave them in long enough to liquefy the
adhesive and mount, and be certain to use a breathable tissue (see
"Adhesives", July 1994).
Horror stories of bubbled photo emulsions at 180F are the result of an
unusual emulsion problem or non RC photo.
This is not a routine sensitivity affiliated with all RC photos.
Photos are
frequently laminated, and since manufacturer's suggested press settings for
laminating films will vary from 185F-225F, this clearly illustrates a
photograph's tolerance for heat. Ilfochrome
Classics (aka Cibachromes) will not physically begin to melt until upwards of
325F, though they are best kept out of heat presses altogether for a great many
other reasons.
So fear not the
lowly 180F for mounting photos...just don't leave it in overnight!
TAKING YOUR
TEMPERATURE SERIOUSLY
So what
temperature do you set your press? A
fairly standard, safe setting for daily mountings of paper, photos and fabric
will be 180-190F in either a mechanical or vacuum press, when using a
permanent, breathable tissue. Remember
this will vary with different tissues.
More delicate
lower temperature formulations will average 160F. Always consult suggested temperature settings
and remember that lower temperatures will directly reflect the amount of time
an item must be left in a press. Lower
temps = longer dwell times, and higher temps does not always equal shorter
dwell times.
I'll be putting
the pressure on next month in part three of TTPM!
END
For more articles
on design or mounting search your desired topic under Articles by Subject.
If you know your specific title check Articles by Title.
Additional
information on mounting basics is found in
The Mounting
and Laminating Handbook, Second Edition, 2002, and
The Mounting
And Laminating Handbook, Third Edition, 2008.
Creative
Mounting, Wrapping, And Laminating, 2000
will teach you
everything you need to know about getting the most from your dry mount
equipment
and materials as
an innovative frame designer. All books are available from Designs Ink
Publishing through this website.
Chris A Paschke,
CPF GCF
Designs Ink
Designs Ink
Publishing
785 Tucker Road,
Suite G-183
Tehachapi,
CA 93561
661.821.2188
info@designsinkart.com