Mastering Mounting
by
Chris A Paschke, CPF GCF
Picture
Framing Magazine, February 2012
"Pressure-Sensitive Adhesives and Burnishing"
Unlike adhesives that require heat or moisture to
activate, pressure-sensitive adhesives and tapes bond by mechanical or manual
activation and mutual attraction. Regardless of whether manually rubbed, set in
a cold vacuum frame or run through a roller laminator, any PSA must be
activated by pressure to properly begin its bond. The elements of time,
temperature, pressure, moisture apply to all PSAs including rolled adhesive,
ATG tape, and shipping tape all require some type of burnishing for proper
activation. Anyone who has used their fingernail to rub down cellophane tape
has burnished the adhesive to try to get it to stick better, which is where
bone burnishers come into the picture.
The most permanent method for bonding mats
together is placing a bead of PVA white glue around the perimeter and weighting
until dry, but when ATG tape is used for holding mats together--or applying
dust covers--simply pressing or hand rubbing the surface of stacked mats only activates
about 25% of the P-S bond. Even after full cure the adhesive has not been used
to its full capacity and will fail in time. To fully activate a P-S tape it must
be aggressively rubbed to initiate the first 80% grab. The final 20% of a PSA
bond occurs once fully cured while under weight.
photo 1
Book hinges of linen or
neutral pH kozo tape.+
photo
2
Spacer
butt joins are reinforced
with
Lineco Abaca P-S tape and burnished.
There are numerous applications that call for
pressure-sensitive products regularly used in framing, such as book hinging window
mat to backing (photo 1), butt joins of spacers between mats (photo 2),
decorative paper deep bevel wraps (photo 3), and angled and fitted pinwheel
joins (photo 4) should always be burnished. In addition all fitted joins—reverse
bevel against bevel--should be diagonally reinforced on the under corners to
maintain their snug fit and proper alignment (photo 5).
photo 3
Deep wrapped bevels may be
made
with 3/16" bevel cut
foam, ATG tape,
strips of decorative paper and
a burnisher.
photo
5
Reinforced
joins both vertically and
diagonally
with Abaca then burnished.
photo 4
Pinwheel joins of wrapped
bevels are well fitted.
Bone burnishers should be one of the most
indispensible tools in the frame shop, but is often one of the most overlooked
in day-to-day use. So where is your bone anyway? Perhaps you bought one then put it away for when
you needed it…but that time never came. Or worse yet, you never considered
investing in a bone at all. It's a small inexpensive addition that should be
part of every framers basic tool kit.
photo 6
P-S linen tape makes a great
book hinge,
but it must be fully
activated with a bone.
photo
7
Homemade
knife from dried bamboo (top),
commercial
knife/burnisher (bottom).
Types
of Burnishers
Burnishers—also called bone folders--are
available as horn, bone, stone, metal, wood, and synthetic, but for framing
purposes bone is usually the burnisher of choice (photo 6). The length and
shape of the bone really matters not as far as tool efficiency therefore
whatever is purchased will no doubt become the favorite. They come in a variety
of sizes, shapes and materials used extensively in the making and restoring hand
sewn books and bookbinding. I prefer a more pointed bone—4th from left—but I
also use the shorter more blunt tool and love the commercial OAS Bamboo Papercutter
from Oriental Art Supply, available online.
Bamboo knives/burnishers are a tool of choice for
Asian arts being strong and yet nonabrasive. One end is a sharpened knife for
separating mats, removing applied strips, and cutting folded paper (diagram 2),
while the other is a tough burnishing tool (photo 7). The knife may be kept
sharp by grinding on a course 100 grit 1"x7" sanding stick available
at beauty supply stores (photo 8). A bamboo tool was recently used to help
separate a large 32x40" original painting that had been dry mounted to a
3/16" foam center board which had badly warped (photo 9).
photo 8
Sharpen knife for clean
separation of
stuck mats without fear of
bending.
photo
9
Bamboo
knife used to remove
foam
center from behind mounted
original
for proper reframing.
Selection of the proper burnisher matters not as
far as shape is concerned, but some materials—such as metal—have been known to transfer
a discoloration to mat board bevels. Some materials may also resist sliding
along a toothed surface not allowing them to glide as smoothly as an aged or
seasoned bone. Most alternative burnishers have actually been developed for
other technical uses—vinyl transfer designs, gilding—and should only be used as
a temporary substitute for bevel smoothing while you search for your neglected
bone.
Seasoning
A New Bone
A new burnisher should be seasoned with oil prior
to first use, much like you would a new gourmet sauté pan. Liberally apply
vegetable or corn oil to all sides of the bone and removing excess with a clean
absorbent cotton rag, then let sit overnight to completely absorb the oil. Natural
materials—not plastic or synthetic--will readily absorb the oil into the dried
bone altering the original white color of the polished bone to a softer yellow
(photo 10). The darkening of the bone is the direct result of oil absorption
but will not leave the bone oily in any way.
A seasoned bone is extremely smooth and glides
along the surface. If used to separate window mats or remove strips of art
paper it may become contaminated with adhesive residue which will inhibit a
smooth glide. A little solvent does remove unwanted adhesives but also dries
out the bone, so re-oiling may become necessary. It might be better practice to
have a second bone for separating p-s layers thus reserving one specifically
for bonding pressure activation.
photo 10
New unoiled bone (top)
aged and oiled bone
(bottom).
diagram
1
Folding
paper.
Besides giving the bone a smoother surface, the
reason for seasoning—oiling--is to seal the new bone from the dirt and oil
found on human hands which can make dirty bones sticky. Older untreated bones
will eventually take on a similar aged look but will also absorb other dirt and
contaminants that may make the bone sticky.
Other
Uses
Bone folders are favored for their accuracy of
creasing a correctly squared sheet of paper. Simply align along one side and
run the folder down the folded edge (diagram 1). When cutting most soft museum
rag, 12-ply tiered mats, or when a blade is getting dull, a burnisher easily
smooths down newly cut raw or ragged edges and gives the mat a more polished
and completed look. A ragged unburnished bevel edge looks unprofessional,
unfinished, and has been known to lose a point or two during competition
judging (photo 11). Slight imperfections in mat corners such as tiny overcuts
may also be visually reduced—though never healed--by using a bone. Turned mat
edges may not be the solution to a hooked corner, but they most definitely
should be the professional framers finishing touch.
photo 11
Rough edges to any window
mat bevel
need to be lightly burnished
for a polished finish.
diagram
2
Turning
rough cut bevel.
When cutting very thick 8 to 15-ply pin-striped
or bevel banded tiered mats there is a shifting of the planes at the window
corner. This is merely the result of the blade being inserted then removed from
the very dense board. By burnishing the bottom edge of the bevel from the back
of the mat, shifted corner is flattened and the window is realigned. Since all
burnishing is done from the back of the mat, any shiny spots resulting from a
polishing of the board surface will not be visible.
Less Is
More
Very little pressure is required to smooth the
cut edge of the mat. Do not press hard or aggressively burnish, as too much
pressure may dent the board or remove the crisp edge between the mat face and
the bevel itself. The idea is not to reangle the bevel, just to clean it up
(diagram 2). One quick, gentle slide down each side of the window will turn the
rough edge for a clean cut window. Consider for a moment the impact all this
could have on your professional image. The viewer never quite realizes why the
matted picture looks better...it just somehow does. So if that bone you bought
last year is buried in the back of a drawer somewhere, maybe it's time to dig
it up and put it to some good use. After
all, a bone in the hand is worth two in the drawer.
END
Copyright © 2011 Chris
A Paschke
For more articles on
mounting and mat design basics look under Articles by Subject http://www.designsinkart.com/library.htm
Additional information
on all types of mounting and creative applications in:
The Mounting and
Laminating Handbook, Second Edition, 2002,
The Mounting And
Laminating Handbook, Third Edition, 2008,
Creative Mounting, Wrapping and Laminating, 1999.
Chris Paschke, CPF GCF
Designs Ink
Tehachapi, CA 93561
P 661-821-2188
chris@designsinkart.com