DIP Online
Designs Ink
Publishing Article Archive and Reference Library
Articles
by Chris A. Paschke, CPF GCF CMG
"Digital
Canvases And The Adhesives That Love Them"
October 2006
The digital canvas
debate goes on and on like the Energizer Bunny, and no doubt may never reach any
unanimous resolution (photo 1). There
are two issues that haunt a digital canvas: flaking inks and sagging once
stretched. Flaking inks may be controlled by the correct choice of coated
canvas, ink and printing system, while sagging canvases are tougher to control.
Photo
1 Assorted Test Canvases
(Bottom
to top) Open edition canvases from Wild Apple Graphics,
"Standing
on the Edge I and II" by Cantlin; "Blue Bird Song I and II" by
Goggio (II stretched);
and
Grand Image test canvases "Shapes" and "Palms".
Flaking and Cracked Inks
Earlier this year
I explained the differences between swellable and porous paper coatings for
inkjet printing and how the coatings impact heat sensitivities ("Mounting
Digital Papers", PFM February 2006). These same receptor coatings are used
on raw canvas to make them ink receptive. White digital canvases are not
traditional gesso coated canvas, but rather white swellable or porous receptor
coatings on raw (or bleached white) canvas. These coatings are required to
receive digitals inks and prevent them from bleeding or spreading when applied
to a porous canvas or fabric. The coating controls the ink but in turn impacts
traditional handling of the canvas art. Thus digital canvases come with their
own set of issues, variables, and requirements which react unlike traditional
oil and acrylic canvases.
Photo
2 Flaking and Over Work
The
left sample is a good example of flaking inks from a coated inkjet image.
The
right sample is merely an over worked corner with surface cracked inks but not
flaking.
Photo
3 No Cracking or Flaking
The
left sample feels like a vinyl canvas material, though unidentified.
It
shows not cracking, flaking or damage when aggressively rubbed together.
Right
sample is a digital inkjet on coated canvas that flaked.
Mismatched
materials or untested ink/canvas combinations are generally the ones that have
adverse reactions to the aggression of stretching over bars, resulting in inks
that flake from the canvas at the corners or crack when pulled with canvas
pliers during stretching (photo 2). This problem does not occur with all inkjet
images on canvas (photo 3). Use of
OEM (original equipment manufacturer) products such as an Epson printer, Epson
ink, on Epson approved coated canvas will result in a well printed digital
canvas that does not flake once stretched, though a white line of cracked ink
may still remain visible (photo 4). That
line is merely the surface ink cracking to reveal the white receptor coating
and/or canvas beneath it, though it should not flake off (photo 5).
Photo
4 Surface Cracking
This
sample shows the inks cracked when the canvas is folded 90 degrees,
such
as when placed over bars.
Photo
5 Flattened Crack
This
is the same sample as in photo 4, but has been folded flat to
hide
the exposed white coating beneath the cracked inks.
Some printed
canvases may not be wide format inkjet, but are considered digital offset as
with the Wild Apple Graphic images which tolerate stretching without flaking (photo 6). Although over working of a
corner during stretching can cause surface fractures that are also not
acceptable unless placed into a designated canvas depth frame (photo 7).
Photo
6 Stretched Canvases
Left
sample was stretched for a frame, right sample for float frame or as frameless
gallery wrap.
Though
the inks do not flake the surface cracked inks show on the blue wrapped corner.
Photo
7 Over worked Corner
The
gallery wrap in photo 6 is only surface cracked, this corner has been
drastically
over
worked exposing a great deal of underlying canvas.
Sagging After Stretching
Sagging canvases
are the next big issue with transfers and digital canvases. As seen in the photo
5, many canvases easily tolerate stretching without sagging issues, but this
sample was stretched in the dry high desert of California and not in southwest
humidity (photo 8). So it remains to
be seen if over time and variations in humidity if it will be effected.
Photo
8 Stretched Canvas
This
newly stretched digital canvas remains taut after 48 hours,
but
has not be placed in a humid environment yet. All is well with it.
In the case of a
vinyl coated canvas transfer the surface laminate more readily expands and
contracts with temperature and humidity making it very difficult to keep a
stretched transfer taut. Vinyls get soft and expand in heat and retract in
cold, so a stretched transfer in an air conditioned room will sag once taken into
the summer heat during transport home.
If stretching a
digital canvas is the only choice, sagging must be considered and one suggestion
is to place a 4 ply rag board or 3/16" foam center board support between the bars and the back of the
canvas. This gives added support but will still not prevent the canvas from
expansion puckering. So mounting a digital canvas to a solid substrate is the
best solution.
A Study: Raw and Coated Canvases on P-S and
HA Boards
In a recent study
I compared most accessible name brand pressure-sensitive (P-S) and heat
activated (HA) boards available in the framing market for their overall bond,
T-peel, and shear strength when mounting both raw untreated, uncoated canvas;
and a digitally printed canvas with a receptor coating (refer to Application Comparisons
"PS and HA Mounting Chart" in the library).
P-S products
tested included: Alcan Self Adhesive Fome-Cor LT; Bainbridge SA Foam and SAX;
Crescent PerfectMount Foam and XX; Drytac PS Gator and Foam Board; Elmer's
Bienfang Self Adhesive Foam; Gilman High Tack Foam; Hartman HarTac; Savage
NuCor and Prestax ProCore; and P-S film adhesives applied to selected boards.
Heat activated
boards included: Alcan HA Fome-Cor; Bainbridge Artcare Restore, SpeedMount and
HAF; Bienfang Single Step and Step 150; Gilman Heat Activated Foam; Hartman
HartMount; Savage NuCor HA Foam and Filmtax ProCore; pure film adhesives, and
digital tissues applied to foam center boards of choice (photo 9).
Photo
9 P-S and HA Test Boards
Assorted
commercial P-S boards (L) and HA board (R) were tested with both
digitally
printed canvas and raw uncoated canvas in 210M-X mechanical press
and
4060 VacuSeal hot vacuum system.
P-S Results
The results were
interesting. All boards illustrated a shear strength of 100%, some had
immediate grip, some were repositionable, some only held well after the 2 month
curing period. Since raw canvas is very porous which I expected to bond well to
many boards, not so. The coated canvas has a more sealed surface and backing which
I expected it to be more resistant to bonding, also not so. And the results
were different for both.
Only three P-S
boards bonded the raw canvas at all: Elmer's Quick Stick, Drytac Gator and
Drytac Foam,
all of which are
high tack pressure sensitives. These were all tested using only manual methods,
a brayer and weighting 12 hours for the initial review. All boards were checked
again at two months for aged bonding. Coated canvases held aggressively to
Bainbridge SA Foam, Elmer's Quick Stick and the two Drytac boards. All other
P-S boards showed only 10%-50% bond, even after two months.
P-S film adhesives
like Gudy 870 and 831; PerfectMount film and 3M PMA were also tested. These
films did not fare well with the porous or the coated canvas materials, even
after 2 months.
Heat Activated Board Results
Conversely, heat
activated boards were only marginally successful for digital canvases, but
failed for raw canvases. All tests were done on both 8x10" samples in a
mechanical press and 24x36" samples in 4060 vacuum press at suggested
manufacturer times and temperatures. A range of temperatures are covered with
products mounting at F150 – F200. Bainbridge HAF (Heat Activated Foam) was far
and away the superior choice for digitals, and appears to be one of
Bainbridge's best kept secrets. This product has been around for years but not
well promoted. Beinfang Single Step and Step 150; and Alcan HA Foam were
successful for digital, while only Step 150 and Alcan bonded the raw canvas.
When bonding with
HA materials in a dry mount system one must remember that only piezo images
(Epson and most wide format printers, not HP) may be mounted. Thermal inkjet
images on swellable coated canvas will under press temperatures.
Dry Mount Tissues and Films
Once dry mounting
is being considered as an option, whether a HA board or a roll adhesive/board
combo is selected is up to the individual (photo
10). Pure HA film adhesives like Drytac Pure Film Adhesive and Beinfang
Fusion 4000 have been top choices for HA adhesive for canvas for years because
of the ability of the adhesive to self level into all the highs and lows of the
canvas while bonding. New products like Drytac GicleeMount have been developed
for use with high end fine art paper digitals and canvas mounting. Bienfang
RagMount, a tissue carrier adhesive (unavailable for testing) has recently
replaced their fine art film ClearMount for high end fine art digitals on paper.
Photo
10 Mounted Digitals
Cantlin
canvas on 32x30 3/16" Artcare Foam with Drytac GicleeMount (L);
Goggio
canvas on Artcare Foam with Drytac TriMount tissue;
Grand
Image Abstract on 100% Cotton Rag Foam with GicleeMount (R);
small
8x10" Palm on 100% Cotton Rag Foam and 4-ply AlphaRag (front left and
right).
Photo
11 No Tear Strength
The
mounted canvas may be peeled from this BufferMount on Foam sampler
leaving
a tactile embedded texture in the adhesive. It holds rather aggressively,
but
can be peeled without reheating. This is BufferMount tissue.
Photo
12 Film Tear Strength
The
same digital sampler tears the surface paper of the substrate when testing
for
T-peel tear strength passing all ISO 18932 standards. This is Fusion 4000 film.
Test results of
rolled adhesives allowed the canvas to be pulled from all general tissue
adhesives leaving a canvas imprint in the adhesive remaining bonded to the
substrate (photo 11), while all film
adhesives held fast tearing the surface papers (photo 12). Tissues included BufferMount, Acid Free Tissue,
TriMount, UniMount, and ColorMount. Films included Fusion 4000, Pure Film
Adhesive, and GicleeMount. All were tested at 8x10" in a mechanical press
and 32x40" in a 4060 VacuSeal. This is not to say that tissues do not
hold, but rather they do not have tear strength. Tissues allow the digital
canvas to be pulled, albeit very aggressively, from the mount board while the
film adhesives tear apart the substrate layers. Numerous substrates were also
tested including 4ply Alpharag, 100% Cotton Rag Foam and Artcare Archival Foam (photo 13).
Photo
13 Assorted Substrates
The
tissue and film adhesive rolls were tested on assorted substrates including
4-ply
AlphaRag (L) and 3/16" 100% Cotton Rag Foam. Note the upper left corner of
the
right
sample is the digital ink that flaked from the backing when fold tested.
Dry
mounting prevents that type of damage.
Other Mounting Options
The popularity of
canvas transfers and digitally printed canvases rage on with art being offered
to galleries and customers as traditionally stretched onto bars with diagonal
staples; museum wrapped with the image ending at the wrapped edge fitting into
a deep canvas moulding; or as a gallery wrap where the art continues around the
stretched edge so it may be hung unframed, or in a float style frame. But with
a digital canvas these may not be the only, nor the correct solution.
Framers please
keep an open mind about the mounting of digital canvases, and look beyond the
preservation limitations of Japanese hinges and starch paste. Pure film adhesives
are also museum quality because of their inert and stable nature, though not
reversible. Face mounting of digital photos is fast becoming a mounting option
of choice for many contemporary photographers, but some people consider this
permanent mounting method invasive, period. Though like Ansel Adams who mounted
all of his photographs for long term preservation, these digital images are a
reproduction similar to a photo, and face mounting or dry mounting may be the
best form of long term preservation.
Museums are
frequently dealing with contemporary art that has been mounted this way as
perhaps the best way to help preserve it. Inert adhesives on preservation
quality substrate isn't really a bad idea. Mounting of 21st century digital art
needs to be done using a 21st century method, with 21st century acceptance.
Digital canvases are not your grandmother's oil painting, and just
perhaps...dry mounting it is the best way to present and preserve it.
Note:
A special thank you the Wild Apple Graphic
and Grand Image for supplying the canvases for this study and to NielsenBainbridge
for their continued support in research and education of adhesives and
digitals.
END
For more articles
on digitals, mounting or design, search your desired topic under Articles by
Subject.
If you already know the specific title then search under Articles by
Title.
Additional
information on shipping boxes is found in my book
Creative
Mounting, Wrapping, And Laminating, 2000.
The two most
recent mounting books are
The Mounting
and Laminating Handbook, Second Edition, 2002, and
The Mounting
And Laminating Handbook, Third Edition, 2008.
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