Help, Saggin Linen!

[Tom Edgerton]

I'd be really terrified to use water that hot. Oil paint is remarkably resilient, but anything has its limits. I'm not sure I understand the logic of using hot water. Maybe it affects the fabric sizing or something.

In a pinch, I've misted water onto the back from a plastic bottle/ plant sprayer. Room temperature. Also, I've let it air dry after, with a good result. Some folks would object to water at all, and they may be right, I don't soak the canvas down under any circumstance.

If the canvas was reasonably tight, again, time will lessen the expansion/contraction, but I understand that kind of pressure in a commission situation. Also, not moving it from place to place helps, once it's hung...I've had them slacken from the framer's to my studio in certain seasons. Once it figures out where it's to live, the painting will settle down.

[Terri Thickstun]

I absolutely agree Tom, this was a risky process, not one to use if there are other time tested options available. I should note that I paint fairly thin as well and I'm not sure of the effect this might have if one were to have heavy paint on the surface.
Drawing on my vast knowledge of laundry :-), I do understand that hot water and a hot dryer are more likely to shrink most natural fabrics. The temperature of the water did seem to be key and I can't agree more that this shouldn't be a process in which the back of the canvas is overly wet, it should just be a light touch with a damp sponge to dampen the canvas.

[Tom Edgerton]

No harm, no foul, as they say...

[Richard Bingham]

Young oil paint is amazingly resilient and tough. Old paint films which have become embrittled are likely to crack and fall off the support when subjected to radical stresses.

Painting on stretched canvas is a relatively "chancey" proposition over the long haul, because the support is inherently flexible, and ultimately, the paint will not be. To avoid grief over sagging, slack, or puckering canvases, the best "fix" is for the painter to be knowledgeable on the properties of painting supports - it's hard to beat painting on your own supports if you have the skill and the time to make them.

In short, the most commonly used materials are quite given to "slacking off". Cotton canvas is not particularly strong, and will often become slack simply from the attack of being painted on. This is less of a problem for a glue-sized/oil primed canvas than for one primed with acrylic gesso which does not effectively shrink the fabric, and remains flexible.

Linen is a stronger fiber, but subject to changes in ambient humidity; slacking off in damp weather and tightening up in dry weather.

Hemp is much stronger than linen, does not get loose when worked on, as cotton does, and is much more resistant to changes in humidty, but it is not commonly offered pre-primed or pre-stretched.

Polyester is eminently stable, stronger than natural fibers, unaffected by humidity, and can be painted on directly without sizing or priming, but there is no "old world mystique" to using it.

[Mary Cupp]

I have never seen hemp canvas but it sounds quite interesting. I know the hemp fiber is exceptionally strong. Has anyone had any experience with it?

I use mostly cotton canvas but it is a compromise, as linen is so expensive. I am wondering if hemp would be an improvement without as much expense. Does anyone have any advice on using it?

[Richard Bingham]

Originally Posted by Mary Cupp

. . . hemp fiber is exceptionally strong. Has anyone had any experience with it?

Yep. Search online for hemp products. One source is "Pickering Int'l." where I bought several yards of a very good, heavy hemp twill a couple of years ago. Be advised that searching for hemp products will get you some spam from "legalize pot" groups. :wink:

Be wary of samples that look good. Before buying the twill, I purchased a medium weight square-weave canvas that looked OK in the swatch, but was heavily sized and fullered in the mill. When washed out on the frame, the intestices opened so wide the stuff resembled a screen door.

The scuttlebutt is that the Chinese use a process for preparing the raw fibers that results in shorter staples and a weaker fiber. Hemp processed in Eastern Europe is "done correctly".

Oh! Cost? As I recall, the hemp twill ran about $10 per running yard at 72" wide. I never use cotton to make up my own supports, and unprimed linen prices vary depending on weight, thread count and running width. I figure the average cost of materials for stretching and priming my own canvases runs about $2.00 per sq. ft., including stretchers and brass tacks.

I wouldn't recommend using acrylic gesso on hemp - prime with a glue size and an oil ground. Hemp can be crabby to stabilize, i.e., it's more difficult to work with and tension correctly than cotton or linen, but once the canvas is finished up, it stays put.

[Jean Kelly]

I've painted on hemp and loved it! The problem is finding one with a subtle texture instead of rough. Mine was quite textured, which was fine for the painting I was doing, but probably not good for fine detail work.

I got it from Dharma Trading Co. unsized and raw. Loved it!

Jean