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| Canvases (clockwise from top) include Fredrix; InteliCoat Torino series; HP Professional Canvas Matte and Collector Satin Canvas; Crane Museo Maestro Canvas-WR; and Epson PremierArt WR Canvas |
More details on the Mastering Mounting column that appeared in the August 2008 issue of PFM
With the popularity of digital canvases (giclées, canvas giclées) continuing to be high on the consumer scale of coveted art, framers need to know how best to present them. It would seem logical as canvases they should be stretched. But prior to bending to customer desires, framers must become knowledgeable of the effects that humidity and temperature variations have on digital canvases, and how different they are from traditional oil or acrylic painting once stretched.
For years I have questioned the receptor coatings, inks, and fiber content as reasons for sagging, but wanted to see if anything could be proven, only then might a solution be found. So during the 2007 Photo Marketing show in Las Vegas I began acquiring manufacturer resources and support for what would turn out to be a rather time consuming and extensive digital canvas study. Here is the report and results to date of Phase One...Stretching.
Test Proposal
The test was designed solely for the benefit of continuing education for our industry with no sponsorship or funding other than materials and supplies. There are three phases to this test. Phase One continues to test both gallery wrap and standard stretched digital canvases in an attempt to target the causes of sagging. Theories included canvas weight, fabric content (cotton vs. poly/cotton); type of ink receptor layer (swellable vs. porous); dye vs. pigmented inks, and reactions to humidity, temperature, or both.
Phase Two tests HA and P-S adhesives and their bonding capabilities for these same digitally printed canvases. Phase Three continues into 2008 with the additional testing of wet glues, pastes and acrylic liquids, polyester batting, and additional stretching variations including needlepunch fabric and rag boards. I have been brainstorming with Hugh Phibbs on this part.
Materials for Phase One
InteliCoat printed the same control image for me on their six basic Torino canvases with both dye HP5000 and pigment Epson 7800 and 9800 printers for comparison. Their 17M, 20M, 21M canvases are matte finish with porous receptor layer for pigment ink, and 20G, 21G gloss finish with swellable receptor layer for dye ink shows a detail of the gloss and matte finishes.
One of the most interesting observations was the dramatic variation in image color on the assorted InteliCoat canvases when printed using the same printer. It is easy to tell the difference between 100% cotton fiber canvas and cotton/polyester blend fibers by the color. Cotton canvas is an unbleached natural cream color on the back, is softer to stretch, and never stays flat always rolling up regardless of manufacturer.
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Canvases are designed for use with either dye or pigment inks. Gloss surface (G) are swellable receptor layers best for dyes and matte (M) are porous receptor layers best for pigments.
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Upper left is a matte porous layer of Torino 20M while lower right shows a gloss swellable layer of Torino 21G. |
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The two gloss, true color canvases 1 and 3 (L to R) were printed with HP5000 on 21G and 21G canvases designed for use with dyes ink on a swellable receptor layer. The other drab canvases are dye ink on a porous layer, not the best choice. |
Procedures
All canvases were thoroughly researched for material specs as per receptor layer, finish, canvas weight, suggested inks, water-resistance, and thread content for cotton or poly/cotton, for cross reference and comparison, then applicable information was recorded in spreadsheet. Manufacturer suggested uses such as fine art, photo, gallery wrap. Additional notations recorded manufacturer disclaimers, best print temperatures, and humidity.
Fixed corner strainer bars were constructed 16x20" at the 1-7/17" depth and canvases were gallery stretched and stapled to the back of the bars. Canvases were not surface liquid coated or sprayed, nor back misted to tighten. They were labeled per type of canvas, printer used, and ink type (dye or pigment). All samples were noted on the spreadsheet for ink reaction at sides, corners, and staples. Also ink tolerance to rubbing, surface scratching, and scuffing was recorded. Corners were neatly tucked and creased at the corners to check for cracking or splitting inks.
Images were stretched and side stapled in traditional wrap manner and some were back stapled as a gallery wrap. All stretching was manually done using canvas pliers, pulled drum tight during May 2007, when average Tehachapi temperatures were 75°F-80°F with 10% relative humidity. Waiting until the warmest month or coldest month of the year to stretch any canvas for considered maximum thread "give" is a little unlikely. Our customers want it now, not after spring thaw.
Although checked daily for significant changes the canvases were allowed to settle a few weeks before results were officially recorded. They continued to be recorded every few weeks or daily when there was a significant change in temperature or humidity. There were also controlled segments of constant temperature and humidity for set periods of 12, 24, and 48 hours in a sealed room with heater and humidifier. Again results were only recorded when a difference occurred. All canvases were rated on a scale of T=drum tight, T=taut, L=loose, and S=saggy.
Though HP suggests misting the verso side of its stretched Collector Satin Canvas to tighten, this was not done until just this past month. There is a product available called Tight'n'Up by Masterpiece Artist Canvas. It is called an archival, acid free, canvas re-tensioner that shrinks canvas fibers when applied to the verso side of a loose canvas. This is a commercial tightening agent sold for use with traditional paintings not marketed for digitals. Copper tacks may also be used instead of staples if preservation methods (as per MCPF exam) are being promoted. It dries clear but no ingredients are listed on the bottle.
Tight'n'Up was misted on the backs of three canvases that consistently had sagging issues, and it immediately had a tightening effect. These will be monitored for future reactions and have been noted on the spreadsheet.
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(L to R) HP Collector Satin Canvas, HP Professional Matte, Torino 20M, and Fredrix matte. The cotton natural unbleached creme on the back, is softer to stretch, and never stays flat always rolling up regardless of manufacturer. |
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Fixed corner strainer bars were constructed 16x20" using 1-7/17" depth and canvases were gallery stretched and stapled to the back of the bars. |
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Ink tolerance to rubbing, surface scratching, and scuffing were recorded. Torino 17M and Decor as well as Crane Museo Maestro all chipped at the staples. |
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| Corners were tightly tucked, folded and creased to check for cracking or splitting inks. This Wild Apple Graphics Digital Offset rubbed a little but never cracked. |
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Images were stretched and side stapled in traditional wrap manner. All stretching was manually done using canvas pliers, pulled drum tight during May 2007, when average temperatures were 75F-80F @ 10% relative humidity. |
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Some were gallery wrapped to check if stretching technique impacted the sagging outcome. This Epson Premier Canvas stretched nicely to narrower 1/2" deep strainer bars. |
Results
Assorted ink cracking at stretched corners, edge splits and cracks at the side fold, edge wear from rubbing during stretching, chipping at the staples, and surface scratches and scuffing all occurred on various samples during the stretching process. Although liquid laminate applied to canvas surfaces will deter ink damage during stretching, since a framer is not allowed to apply surface coatings these ink problems will continue. When digital inks are applied to a receptor layer on the top of a canvas it is a natural result for the raw canvas beneath to be exposed when the solid surface has been split to turn a 90 degree edge at the side during stretching. Liquid laminates better allow the inks to bend at the edges which results in less severe cracking or visible splitting. Surface scuffing will also be reduced by the application of surface coatings. Without a surface laminate the chipping and cracking will continue.
Framing options for digital canvases include stretching, mounting, or a combination of the two. Test results illustrate an inconsistency with the tautness of all stretched canvases. Many fabrics prefer cold temps/low humidities, but others liked higher temps/higher humidities, with average temperatures and average humidity were not necessarily producing the best results. The biggest issue is a lack of predictability.
Unfortunately the results show no obvious pattern for when digital canvases are expected to sag. The theory of a canvas being too lightweight for an oversized image is inconclusive because assorted oversized images were not tested. Other theories of swellable vs. porous receptor layers, or cotton vs. poly/cotton blend canvas also proved to be inconclusive.
While many of the tested canvases are best when printed between 65°F-80°F at 40-60% relative humidity, once stretched, canvases preferred room temperatures with fluctuations of 50°F-70°F at 10-40% humidity, with the best results between 40°F-65°F at 10% humidity. Once the canvases were moved to the colder storage area in February and subjected to more consistent cold and humidity they flourished at daytime temperatures of 50°F-60°F at 30-50% humidity.
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(Above) Canvases are step staggered to indicate canvas tension as drum tight, taut, loose, and saggy. The Epson printed Torino group at left shows five drum tight, one taut. The three small 10"x10" in front show two taut and one drum tight. Right group (back to front) shows two taut, two drum tight, two taut, one loose, one drum tight, one taut. These are rearranged and recorded when changes occur.
(Right) This is a commercial tightening agent sold for use with traditional paintings not really digitals. The HP canvas behind suggests misting the back with water. Copper tacks may also be used instead of staples if preservation methods are being promoted. |
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Conclusions
Tests have proven from these samples that cotton vs. poly blend fiber content has little to do with sagging, nor does a swellable or porous receptor coating. Dye vs. pigment ink is also not a factor. Canvases with greatest consistency were Torino 20M and 21M for both dye and pigment; HP Collector and Professional Canvases; and Crane Museo Maestro Canvas. Printers didn't seem to be a big factor.
Cracking occurs only because the receptor layer keeps the ink sitting on top of it and when bent it splits the ink to reveal the uninked canvas below the surface. Liquid coatings can help allow the surface to give more during stretching that might better prevent the side or corner splitting, but is unlikely to totally prevent it. It is the nature of the beast.
Since stretching is so unpredictable it is advised that any manufacturer/publisher fully research both the desired printing results of their canvas when used with their printer of choice as well as testing stretched end products under temp and humidity extremes. It is ill-advised for any framer to apply liquid laminate or spray coatings of any kind to the digital canvas surface. It is not impossible for any framer to know the combination of canvas type, ink, printer, coating, and temperature/humidity tolerances of any printed canvas they are asked to frame, nor can they predict how it will react to stretching. So whether to stretch or find an alternative mounting method remains a personal decision.
Final Stretch
Had I written this in February, prior to moving the canvases into colder storage area I would not have noticed their comfort at the lower temperatures and humidities. Tests had already shown canvases were more predictable under 50% humidity but the combination did not really show up on the chart until February and March 2008 recordings. So the test continues, with new canvases being added monthly.
Phase two and three of this test will be reported in Mastering Mounting over the next year as information becomes more complete. In the mean time, basic digital canvas discussions and guidelines are available in The Mounting And Laminating Handbook, Third Edition available through PFM Pubco Bookstore now featuring blank Condition Report forms for stretched canvas projects. Updated results, spreadsheets and on-going test information for this and other projects will be available at a new framer library and resource website www.designsinkpublishing.com, currently under construction for launch in 2009.
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