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Author Topic: Canvas Shrinkage when Printing and Coating  (Read 2579 times)

edknightphoto

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Canvas Shrinkage when Printing and Coating
« on: October 10, 2014, 12:36:18 pm »

Before trying my hand at canvas printing and stretching, I did lots of reading on the web and found lots of conflicting advice regarding canvas shrinkage.  Decided to do my own experiment to get answers to my combination of ink, canvas and coating.  So, FYI, here is what I found. 

I printed with a Canon ipf6400 using custom profiles and PS contrast curves on rolls of both BC's Lyve Canvas (ipf's Cotton Matte2 Media Type) and Epson's Exhibition Natural-Matte Canvas (ipf's Fine Art HW Photo media type) with a sprayed over-coat of Premier Art's Glossy Eco Print Shield (3 coats).  Both canvases are poly-cotton blends.  When I sprayed the printed canvas, the entire length of all 4 sides were attached to a backing (over-spray) board using painters tape.  That's lots of tape, but that's the cheapest part of the process.  I took shrinkage measurements on the largest prints of 22"x48" and 12"x36".  I only observed shrinkage in the long dimension of the canvas on the roll.

Shrinkage when printed:  Lyve 0.29%; Exhibition 0.55%
Additional Shrinkage when Coated:  Lyve 0.0%; Exhibition 0.0%

D-Max when printed:  Lyve 1.61;   Exhibition 1.55
D-Max when coated:  Lyve 1.65;   Exhibition 1.75

There's lots of comments on the web that shrinkage occurs when coating the canvas, not when printing.  This is certainly not what I observed with my experiment, though results could change with a different combo of materials.  It's also possible that, by taping the entire perimeter of the print when spraying, I eliminated any additional shrinkage from that process.

I've questions on the effects of humidity changes on the tightness of the stretched canvas, but again I found lots of conflicting advice.  However, I did find a FAQ on the Masterpiece Arts site (An art canvas manufacturing/sales company) stating that stretching a canvas in a humid climate and moving it to a dry climate will make the canvas loose.  I figure they are pretty authoritative on questions concerning canvas.  I find their comment comforting as I'm stretching high in the Rockies where it's very dry, hoping that my first efforts at stretching will only improve as I ship it elsewhere.  The 36" wrap is going to my son in Charleston SC to see how it holds up in that very different environment.  You can ask me how it went after next summer.  The 48" print is going to a paying customer near Dallas, so I'll keep my fingers crossed in the hopes I won't have to replace or fix due to sagging.  Cost of OTJ education, if there are issues.

I previously had wraps done by Simply Color.  They used Epson inks on poly-cotton canvas and included instructions to lightly spray the back of the canvas with water if the canvas becomes loose.  Again, I've found lots of conflicting advice on the web ("Never spray the back of a glicee/ink-jet canvas...", "Poly-cotton canvas will not tighten by spraying the back..." etc, etc).  Well, I sprayed the back of my smallest wrap (11"x14") and have not seen any damage to the print, but I can't answer the question about whether it tightened simply because I can't remember from one day to the next how tight it sounded.  Suppose when a wrap sags, I'll see if this works.  It's interesting that one of my letter-sized test prints (Exhibition) mistakenly fell in a bucket of water between coats of Print Shield, soaking portions of the canvas and there was no apparent harm done.  In this instance the tape fell off, thus my use of tons of tape on the more important prints.
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jferrari

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Re: Canvas Shrinkage when Printing and Coating
« Reply #1 on: October 11, 2014, 10:28:44 am »

I'm not sure of your specific questions but if you are concerned about canvas shrinkage in a gallery wrapped situation you are barking up the wrong tree. The canvas is not your problem it's the wood in the stretcher/strainer frame that changes it's dimensions to the point of allowing the canvas to "sag." If you could invent a strainer frame that was not hygroscopic the masses would beat a path to your front door!     - Jim
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fetish

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Re: Canvas Shrinkage when Printing and Coating
« Reply #2 on: October 13, 2014, 05:10:07 pm »

Actually quite a bit of 'shrinkage' comes from the constipated feeding of the soft canvas material thru the printer. you might want to add 1-1.2% more image size to the direction of the material feed to counter the issue.
Canvas shrinkage from liquid lam is negligible when compared to the feeding issue, and have wayyy too many variable to control unless you have access to a well controlled environment.
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tamtation

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Re: Canvas Shrinkage when Printing and Coating
« Reply #3 on: March 12, 2015, 05:19:43 pm »

With that being said, which canvas do you perfer? 
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Landscapes

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Re: Canvas Shrinkage when Printing and Coating
« Reply #4 on: March 12, 2015, 06:03:24 pm »

I agree that the canvas doesn't shrink when coated.  The reason for the canvas being shorter than it should be is I think simply that the printer isn't reading the advancement of the canvas properly.  I never got around to doing the calibration in my 6400 for length, but there is the option in there to do this for each media type.  I'm not sure if this would introduce banding mind you, as this setting seems to be used both for length or banding, but its worth playing around with I guess.

What I do is I just increase the image size.  So if I need my canvas to be 72 inches long, I would actually resize the image, making sure it doesn't resize the other dimension, to about 72.5 inches and it comes close.  Its a matter of trial and error, and different canvases do need more or less.  I'm not sure how the printer reads how much the canvas is advancing, but perhaps the texture of the material fools this a bit.

In terms of spraying the back in order to shrink it, this works really well for the cotton/poly blends.  There is only so much it will shrink, just like your jeans in the wash, but it will work.  This will also work if you get a dent in the canvas.  Simply spray from the back the area where the dent is, and as it dries, it shrinks and the dent gets stretched out.
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Mike Guilbault

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Re: Canvas Shrinkage when Printing and Coating
« Reply #5 on: March 12, 2015, 11:03:14 pm »

Breathing Color sent me a new ICC profile for Lyve on my Epson 9900. I was getting almost 1/2" of "shrinkage" before that, but now it comes out perfectly. I believe the feed was adjusted by -25.
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Mike Guilbault
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