Loose canvas - what a pain!

[Underworld_Artist]

I stretched some canvases really well, primed them and they were nice and tight. Now two months later they are quite loose.

They're not drum tight anymore and there's quite a bit of flexibility there. Is a slightly loose canvas really a huge problem? I feel like I'm loosing the battle since the UK climate seems to be quite humid. It's been freezing recently, so the temperature inside my house has been going up and down like a yo-yo (as it could be in a buyers house).

I'm almost tempted to give up and paint on wood panels (which probably come with a range of problems too)!!

[NancyMP]

Usually humidity helps, if applied in the right places. Dampen a sponge and rub it across the back of the canvas, or use a spray bottle of water on the back. either way, it should tighten up in a few minutes.

[WFMartin]

Originally Posted by NancyMP

Usually humidity helps, if applied in the right places. Dampen a sponge and rub it across the back of the canvas, or use a spray bottle of water on the back. either way, it should tighten up in a few minutes.

Yes, that is exactly what I would recommend. If the canvas sags in the corners, or directly over the stretcher bars, I often use a putty knife, and fold a wet paper towel over the tip of it. I tuck it between the stretcher bar and the canvas.

After you pull it out of the corner, give the canvas a bit of time to tighten, and often a hair dryer will speed the process, especially in your climate.
Canvases are very susceptible to changes in humidity, and when stretched during a dry time are likely to become loose when the humidity rises.

But dampening the back of the canvas (provided it hasn't been sized with rabbitskin glue, which remains water soluble forever) is a very good way to tighten a canvas without resorting to using all sorts of mechanical means.

[Underworld_Artist]

I've already started painting on this canvas. I thought you weren't supposed to wet the back of a canvas once it's painted on?

[NancyMP]

I have often wet the back of canvas I've painted on. Especially if I've painted with a lot of energy and the canvas loosens because of that!

[vensunn]

Here's what I have learned from my research and have done this when needed:
It's OK to "spritz" (spray with water) the BACK of a stretched canvas.
Spray water uniformly over the entire area of the back of the canvas, yes let it run under the stretcher area too. When dry, it should be taught. Sometimes it takes more than one application. Of course, distilled water is the preferred "purist" medium.
Steven

[artistdale]

Loose canvas is one of the biggest problems artists face but few will admit it. I solved it through much trial and testings. I still get one now and then but I've finally limited the problem. I don't paint on a canvas until 2 or 3 months after making it. If it's still tight in 2 months it'll probably stay that way for a long time.

This problem is common with both linen and cotton canvas. Often the cause is not poor stretching but poorly made stretcher bars. Today I will not buy commercially made stretcher bars. The problem is in the corners. All the commercial bars I've purchased had very poor corner joints. These tend to move and cause those canvas dips in the corners. If I used the store bought bars I'd only buy the heavy-duty bars and I'd glue them together first. After the glue was dry I'd really sand those corners making sure not to round them. But the homemade with nice clean corners are superior.

Those corner wedge slots were a bad idea when invented and they're still a bad idea. They unevenly stretch a canvas and no real conservator would ever remove sag by using them.

In the future, learn to make your own bars and then put big-time muscle into stretching that canvas. PVA sizing tends to relax the canvas a bit after it's fully dried. The gesso will tighten it a little but that original stretching must be done exactly correct or there may be problems.

Also, don't gesso the back of the canvas. Leave that natural except for the sizing of course. The reason for this is, if the canvas gets bumped and dented one can spray water on that spot and the dent will usually disappear. Some dilute rabbit skin glue in distilled hot (not boiling) water (1 part glue - 9 parts water) and spray that on the dents.

Canvas is a blessing and a pain.

[Eduardo Flores]

The above suggestions are the solution.

For avoiding loosing after the canvas is stretched, I use to stretch it wet: it will shrink a little when drying and become a lot more stable.

Your problem comes from the dry canvases having absorbed humidity from the air, so increasing slightly their dimensions.

Eduardo

[Underworld_Artist]

I'm scared of restretching it incase it becomes too tight in summer. When they were made, they were perfect! I was really proud. I'll try the rewetting thing.

The stretcher bars I use are John Jones Tulip wood ones, 32mm deep, and 60mm across. They are a very tight fit in the corners - it takes some effort to slot them together.

[kate252]

did you make your canvas with canvas pliers?

[paint-by-numbers]

Loose canvas is the worst. I buy all mine normally, but I let a friend buy me a canvas to do a painting on for him. Of course, he was clueless and bought the cheapest one he could find. It's all painted now, but it's so loose and pushed in and picks up shadows and reflections in the indentation and looks like crap. I heard spraying water on them can help, but that can only do so much. Good luck fixing yours OP.

[sarastar]

I have had very good luck with spraying the back or sponging the back with water when the canvas gets a dent in it or sags a bit. Tightens it right back up! Best of luck and let us know how it turns out.

[Ron Francis]

Underworld,
How did you prepare the canvas?
Did you size it with rabbit skin glue?

I have never had a problem with loose canvases, and all I do is stretch them dry, wet the back while priming with acrylic gesso. At least three coats.
I have never had to use wedges either and the canvases can be fairly large.

This is why I ask about rabbit skin glue. It is hygroscopic (absorbs moisture) and therefore will expand and contract with moisture in the air.

[musequest]

I have never had this problem of a canvas becoming loose either,and I never buy ready made canvases because most of them have mediocre.I have always bought rolls of canvas..top quality canvas which is very available here in Morocco and at a very good price.I stretch it,applying cosiderable physical engagement,so it feels like as tight as a drum.When I double prime it,it gets even tighter you could tap on it to hear a drum like beat.Some canvases I still have are more than 6 years old,and are still that tight.

[Underworld_Artist]

To answer your questions -

Handstretched - so no pliers.

12 oz cotton

The first two coats that went on the fabric was GAC 100.

The next two layers was Roberson Acrylic Gesso.

My canvas size is 40 x 30inches (I think this is around 1 meter by 70cm )

Just out fo internet, what kind of climate do you live in Ron? Very dry? Where I live it's normally between 70% - 100% humidty outside. Right now it's 96%.