Stretching Canvas - How Tight is "Just Right"?

[Light Seeker]

I've stretched a grand total of 8 canvas prints now, and I'm wondering how tight is "just right".

The last two that I did are nice and tight, and they sound a bit like a drum when I tap them. However, the edge of my gallery wrap (on two sides) is ~ 1/8" over and on the side, rather than being right on the edge.

In contrast, an earlier print that I wrapped seems firm, but it does not resonate like a small drum when I tap it. There is just a dull thud. The edges seem to line up better on this one.

I fear I may have over-stretched my last images. If not, it looks like I'll need to size my image about 1/8" smaller in each dimension.

BTW, I'm printing on Breathing Color Lyve, coated with Timeless. These are 14x18 and 14x22 prints.

I appreciate your help.

Terry.

[langier]

Depending on the thickness of your frame, you may need 2.5 inches or more image per side to wrap. Main thing is what you think looks best. I don't think as tight as a drum is that critical though I may be wrong.

If you want a little tighter than pulling by hand, get some canvas pliers to let you pull a little tighter and make it look a litlte bit nicer.

Hth,

Larry Angier

[bill t.]

I would say "subsonic dull thud" is correct on a large canvas that has been stretched for a few weeks, and "audible dull thud" for the sizes you mention.

The tricky part is, obtaining a long term stable tenion may require a greater amount of initial stretch for different types and treatments of canvas.  And the width and depth of the stretcher bars and the amount of cross bracing is part of the equation, too.  And the type and amount of coating.  And the polarity of the major stretch axis in relation to the weave.  And the particular fabric the manufacturer happens to be using at the time, which may change without warning.

Have only recently gotten back into stretching so can't comment on the current canvases.  But as soon as possible you want to set up test cases with the canvases and coatings and bars you plan to use.  Make careful notes about how and how much you stretched them, then watch as things develop over the next several days.  I think it is possible to get most canvases tensioned correctly initially so that they never have to be re-tightened, but that takes experience and long term feedback.

One thing you might find useful is to go to the local artists supply store and tap some of their pre-stretched canvases.  The guys who make those things have it pretty well figured out, those are usually good references for proper tension.

If you're pulling canvas too far over the edge, just make a note of how far that is, and next time cheat the starting, un-tensioned side backward by about 1/2 that amount.

If alignment is bugging you, trying printing an outline well outside the image so you can easily see it from the back of the frame when you are applying stretch, watch how it lines up with the edges of the bars as you add tension.

[dgberg]

The lineup on the front is more an alignment issue then one of under or over stretching. You may just have to offset abit when starting your first row of staples as Bill notes.
In my house and gallery I have 50 stretched canvases,and monitor them regularly. I use the gallery stretcher machine and started stretching using a setting of 30 pounds . I started to see a rippling effect in the fronts of many of my prints,as in quite loose. I backed off a little on the pressure more towards the 20 to 25 pound setting and have seen an improvement. I may have overstretched the fibers and after a period of time the poly/cotton blend relaxed and of course loosened up. I have more issues with slack canvas on gallery wraps when the temperature is cold. I do not get many folks through here in the winter and have the heat set to 50 degrees. Over these winter months almost all the wraps in that room are slightly looser then the ones in the house. Most gallery wraps will loosen up over time, its just a question of how much. If you do not have it already buy yourself a spray bottle of "Tighten Up",works pretty good.

[Dward]

As Dan says, "Tighten Up"works fine, but so does a fine spray of water on the back of the canvas.   This also works to take out dents caused by poking fingers.

I think the sound of a properly stretched canvas varies tremendously by brand of canvas.   Lyve has a much duller sound than Sihl, for example

One problem with over-stretching is deformation of the strainer.   Unless the wood is quite thick, excessive tension can cause racking, especially if the piece is moved from a cool, high humidity environment to a warmer, drier location.   The shrinkage over-tightens and causes the strainer to twist.

David V. Ward, Ph. D.
www.dvward.com
David V. Ward Fine Art Photography

[bill t.]

Dan, how are liking the stretching machine?  Parametric tension, now that's sweet!  I'm going back and forth on picking up a used Canvas Stretching Machine, need to act soon.

Another issue is that when hand stretching canvas there is a tendency to tension the centers of the bars a lot more than the corners.  Things are lot more challenging stretching near the corners, one tends to get slack in that area in every sense of the word.  A sagging canvas is bad enough, but one that is also puckered from uneven tensioning is a sorry sight indeed.

[dgberg]

Bill,
It would put an end to uneven tensioning for you. Typical gallery wrap stretch takes all but 5 minutes. Worth every penny of its cost.
 Everytime I stretch a long pano (Over 60") by hand I swear I am going to add the 36" extension the Gallery Stretcher Company sells.

[Light Seeker]

Thank you for all the excellent advice and suggestions.

As a bit more background, I'm stretching my canvas onto 1.5" stretcher bars and I'm using good quality stretcher pliers.

The lineup on the front is more an alignment issue then one of under or over stretching. You may just have to offset abit when starting your first row of staples as Bill notes.

It seems that the side I start with and either the top or bottom (depends which I stretch first) are correctly aligned, but the opposing two "legs" are off. When I stretch I pull about 1/4" of canvas with my first tug, which then relaxes back to ~1/8" of canvas stretched by the time I get the staple in. Put another way, I'm not just snugging / tightening up the canvas, but really stretching it. These are the sides that are off.

On a related note, I saw a bit of "distress" on one edge on the last one I did, leaving me a bit concerned that canvas may start to showing (e.g. ink cracking) in time. However, I also had about 9 days between spraying and stretching, which is not optimal.

One thing you might find useful is to go to the local artists supply store and tap some of their pre-stretched canvases.  The guys who make those things have it pretty well figured out, those are usually good references for proper tension.

What a great idea!

If you're pulling canvas too far over the edge, just make a note of how far that is, and next time cheat the starting, un-tensioned side backward by about 1/2 that amount.

I noticed that my stretcher bars measure ~1/8" smaller than spec. A 14x22 stretcher frame really measures 13 7/8 x 21 7/8. I have assumed this is to account for the canvas thickness. If not, perhaps I do need to size my prints a bit smaller.

If alignment is bugging you, trying printing an outline well outside the image so you can easily see it from the back of the frame when you are applying stretch, watch how it lines up with the edges of the bars as you add tension.

I've done that, and my marks on the sides that have been stretched go further in on the back of the stretcher frame.

Terry.

[John Nollendorfs]

One thing no one has mentioned about the stretching process is how canvas will shrink after you apply an aqueous protective coating. Of course every canvas type will be different, but on the IJ water resistant canvas cotton/polly I'm using, I see where it will shrink by 1/2" over 60".

So I have gotten into a routine of spraying my canvas', and stretching them within a few hours instead of waiting days for the coating to cure. If I wait a day or two after spraying, the canvas will have shrunk already.

[Light Seeker]

So I have gotten into a routine of spraying my canvas', and stretching them within a few hours instead of waiting days for the coating to cure. If I wait a day or two after spraying, the canvas will have shrunk already.

John, does that mean you do very little, if any, stretching when you assemble within a few hours?

Terry.

[davidh202]

I have been stretching art canvas, paintings,and gallery wraps, by hand for nearly 25 years. I have also been stretching before the coatings are fully "cured" which in theory should make the canvas more taught as it  shrinks while continuing to fully dry.You never want to stretch too tight as you run the risk of cracking at the edges .
As others pointed out, it really depends on the type of material. it is something that becomes second nature after a while if you do enough.Pactice makes perfect ;-)

One thing I have noted on the few "canvas stretching" videos I have watched,  is just about every one of them use the wrong proceedure.
The proper way to stretch and staple is to line up the canvas to the bars and stretch and staple once to the center of each opposite side, while rotating the canvas. After making sure that your aligned ok, then add one staple outboard  of each side of the center staple,again rotating to opposite sides of the canvas until you get to near the corners. At this point you need to do your corner folds and finalize the corners.
Stretching this way ensures your canvas is taught from the center outward, and evenly stretched.  

[Light Seeker]

David, I'm going to have to give that approach a try. Thanks for sharing it.

Terry.

[dweaverframe]

For years we had struggled with maintaining a tight stretch during and especially after the stretching process.  It is no mystery that canvas is greatly effected by temperature and humidity, it perhaps is a little less known that spraying the back of the canvas with water will provide a temporary solution.  Spraying the back with a slurry of wood glue and water will last even longer.  However, I would argue that the canvas was never fully stretched in the first place.  About a year ago we noticed that the radius on the top of the stretcher barn greatly impacted the degree of tension on the face of the canvas. The more pronounced the radius the easier it was to "pull" the canvas across this edge.  The canvas is not just being pulled across the radius at 90 degrees, it is being pulled across another edge directly below it and this edge typically does not have a radius.  The canvas is actually being pulled a full 180 degrees away from the direction it was traveling.  This hard edge on the bottom of the stretcher bar resists the stretching force and actually prevents the canvas from traveling to a "fully stretched" condition. Naturally, we are only really drawing the canvas taut, not stretching it, but I contend that it is not traveling fully in the time that the operator is giving it.

We started passing assembled stretcher frames over a 1/8" round-over bit on an inexpensve router table.  It takes moments to do but the results are dramatic.  The canvas stretches quicker and with far less stretching force. I have a stretched piece of art that has been sitting in a poorly heated, rather humid environment for a little better than a year and it is still as tight as the day I stretched it. We consider a canvas to be sufficiently stretched when it sounds like a "tom-tom" not a "snare-drum".

Try rounding over your stretcher bars, it really, really works.

[RFPhotography]

Sounds like you're making your own bars?  If you buy pre-made commercial bars, you'll see that they come with a radiused front edge and are tapered from outside to inside on the front.  If you're not doing that with your home made bars, I'd suggest it.  Pretty simple to put a table saw blade on a slight angle and run the pieces through.  I do that then use a palm sander to round the edge (as opposed to a router).

[dweaverframe]

Actually, no...we purchase length from Decor. The stretcher bar is 1.5" x 1.25" and it does in fact have a radius on the top and it does slope inward, however, the bottom of the stretcher bar is in fact a hard edge.  We round over the bottom of the stretcher bar and the results are dramatic.

[RFPhotography]

OK.  Now I understand.  Sorry for the confusion.