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Articles by
Chris A. Paschke, CPF GCF CMG
"TTPM…The Four Elements of Mounting"
April 1992
In my January
article "Adhesive Trends for 1992" I mentioned the four key elements
to successful dry mounting as TIME, TEMPERATURE, PRESSURE and MOISTURE. Although this is geared more directly to
heat-set tissues and films, the same should be respected in other mounting disciplines
as well. Predictability is the hallmark of dry mounting. When repeatedly mounting items over and over
again, the end product should turn out the same each time. Generally speaking if there is inconsistency
with your dry mounting it may usually be tracked to one of the key elements
being out of sync with the others.
It would be
nice to be able to lay blame on the equipment, tissues or the manufacturer's
lack of quality control, because then we could successfully avoid wearing the
responsibility of problem mountings.
Unfortunately, quite often it is our very own inconsistency or attention
to details which gets us into trouble.
Overused or wrinkled release papers, foam rubber with divots torn out
and transferring strips of adhesive to the face of a newly mounted print are
often key offenders in the graveyard of unsuccessful mountings, all of which
may be tracked back to operator error.
The ratio of
time, temperature, pressure and moisture (humidity) vary depending upon the
mounting process, equipment and adhesive being used. The basics of wet, spray and pressure
sensitive mounting follow the procedures to be outlined here, but at times also
include the elements of "tack time" also called "open time"
as well. This is the workable time
allowed by the adhesive to position the print to be mounted as the solvent
evaporates. Open times vary depending on
the product so be familiar with its proper usage.
Application
time also comes into play with wet and spray adhesives in that a good uniform
coat of adhesive must be applied in order to quarantine good adhesion. Any areas which have begun to dry prior to
mounting the art will not create a lasting bond. Although a basic bond will be created within
the first hour, more permanent bonding will take 4-24 hours and should be done
in an undisturbed area under pressure.
TIME
The time it
takes to dry mount a project will vary depending upon the adhesive, substrate,
size, temperature and item being mounted.
As discussed in "Adhesive Trends for 1992" (PFM, January '92)
tissues and films mount between 165-185F.
The "dwell time" is the time remaining in the press to
adequately heat all inert materials, activate the adhesive and create the bond. If a project is removed too soon for proper
bonding it may be repositioned in the press for a second time. When taking this additional step a couple of
important items need to be remembered.
First, if left in the press for 2 minutes under the initial mounting in
order to achieve an additional 1/2 minute of dwell time the project must remain
in the press a total of 2-1/2 minutes the second time. Second, as a direct result of having to mount
the project an additional 2-1/2 minutes you have now not been time and cost
effective.
The important
thing here is to match the proper time/temperature ratios. Since it is increasingly desirable to dry
mount at lower temperatures the dwell times will become a little longer. Simply because a particular print may easily
tolerate a higher temperature does not suggest turning up the temperature to
cut down the time required to mount.
This can be a risky endeavor and quite often you will be the one to
lose. It is far better to work at lower
temperatures with a slightly longer dwell time than to up the temperatures in
an attempt to speed up the production process.
TEMPERATURE
As already
noted it is impossible to give the end all temperature to be used in every
situation, for adhesives range from 150F to 225F. Individual tissues and pure adhesive films
vary depending upon the item being mounted and its substrate, however common
sense should help you consider the layers of board to be heated up for the
required final mounting temperature to be obtained.
For example, an
11x14 piece of velour fabric being mounted onto foam board for a shadow box
creation using pure adhesive film (Fusion 4000 or TM3) may be pressed at 185F
for 2 minutes while an 11x14 4-ply mat board with 3 layers of art paper and a
final 4-ply mat board (all appropriately layered with pure adhesive, to create
a multiple striped bevel) may take the same 185F but for 6 minutes, maybe
more. Quite simply there is more to heat
up to adhesive activating temperature thus the dwell time is greater.
Honestly, it is
best to establish a good average use temperature of about 180F which should
meet most of your mounting needs. Don't
regularly attempt to vary the press temperatures it is a source of frustration
that is never needed.
PRESSURE
Pressure is the
force that squeezes the air from between the substrate, adhesive and print or photo
being mounted. Uniform pressure is mandatory
and in a mechanical press should be set according to the substrate being
used. One of the great advantages to
using a vacuum press is the conformity of the diaphragm (or rubber base) to
totally conform the dimension of the variable substrates being used. Thus if mounting with a 4-ply mount board
then immediately following with a 1/2" foam board and then 1/8" foam
board, no adjustments need to be made to the press. If these variations were needed when using a
mechanical press the lever arm would need to be adjusted each time to create
proper pressure for adhesion.
Keep in mind
the lever arm of a mechanical press should rest at 45 degrees to the table,
with the substrate to be mounted inserted.
Refer to your owner`s manual to determine locking nut and adjustment
screw procedures on your individual mechanical press. It is suggested to adjust the press to the
thickest, most used substrate (say 3/16" foam board) then by cutting shim
boards the size of the masonite beneath the sponge pad, insert them as needed
to accommodate for lesser thickness mount boards.
Proper, uniform
pressure is a must and often may be the culprit when a good bond has not occurred. On the other hand, too much pressure may be
detrimental also. When mounting an
oversized poster in bites using a mechanical press, if the pressure is too
great, indentations may appear on the finished foam board mount, as well as the
press being more difficult to release.
This will be addressed in an upcoming article on oversized mounts later
this year.
Also, never
overlook the need for pressure while cooling the once mounted artwork
("Adhesives", January 1992 and "Work Station", 1992). Once again removable adhesives bond under
pressure once removed from the press.
HUMIDITY/MOISTURE
All paper
products and porous materials absorb moisture. When this moisture is heated in
a press the steam-like vapors which develop may become trapped between the
layers being mounted. Predrying the
materials may greatly reduce the likelihood of this problem from occurring. In a mechanical press it is mandatory the
substrate, print or fabric to be dried, yet in a vacuum press is only highly
suggested. Predrying pulls the water
moisture from the materials before the project comes in tact with any adhesive.
Brown absorbent
Kraft-type paper is used as an inner envelope with a release paper outer
envelope, the press is closed for 15-30 seconds. Repeat this process with the item to be
mounted then proceed to mounting. Many
non-porous materials such as Plexiglas need not be predried since they are
unable to absorb moisture. Cibachromes
should be kept from the press as much as possible since they contort to any
texture they come in contact with when heat is applied, adhesive or no
adhesive.
Perhaps the
clay coated surface and inert core of standard foam board may not need to be
predried, I personally feel it can't hurt.
Once a routine procedure is established, such as weighting all projects
that are removed from a dry mount press, a good habit should not be
broken. Plus if using acid-free foam
board the surface paper is much more porous and predrying is advised.
As mentioned
earlier, the process of predrying is not "required" but rather
"advised" when using a vacuum press.
The very action of the vacuum sucking the air from the press pulls the
moisture out with it. This step in
conjunction with the automatic pressure adjustments of the rubber diaphragm
make the hot/cold vacuum system very appealing.
TROUBLESHOOTING
Now that time,
temperature, pressure and moisture have all been addressed, let's consider what
might happen if any one of them is out of balance with the other three.
If large
2" air bubbles where appearing under a poster mounted to 3/16" foam
board with a permanent breathable tissue core adhesive what might the problem
be? Check the time/temperature ratio to
verify the proper dwell time required, it may simply need a longer time in the
press. Did you use a permanent or
removable adhesive which may have required cooling and bonding under
pressure once removed from the press.
Also check the pressure to ensure the proper 45 degrees for the
materials being mounted. Maybe you
should have predried the print and board even if you are located in a very dry
climate and generally don't predry foam board for it could be trapped
moisture. It could also be the mount
board chosen for the project. Some less
expensive foam boards are better used as backing but not mounting because of
their inconsistent paper bonding to the core which may separate under the
stress of mounting.
All mounting
problems should be trackable. By that I
mean pick apart the elements of the mounting procedure and check all the
steps. Somewhere along the line, the
elements necessary for a good mounting "time, temperature, pressure and
humidity" did not pull together. In
order for your mounting services to be cost and time effective, the four parts
of the mounting puzzle should regularly come together into a quality project,
one completed with confidence, predictability and 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