proper way to finish a stretched canvas

perclop

Grumbler in Training
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May 4, 2005
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Daytona Beach, FL
My concern is about the proper way to back a framed stretched canvas. I have
been told by other framers that the canvas needed to be vented in the back so to
prevent trapped moisture. One framer went as far as papering only the frame and
stretcher bars, then cutting a large opening in the back therefore exposing the
entire backside of the canvas. This may also expose the canvas to possible
dents and tears.
Hoverver Michaels' latest Production Certification manual suggests that we "cover the
back of the stretcher with a rigid, acid-free backing at least as thick as 4-ply
ragboard. Screw the backing to the stretcher bars. ...use a dust cover to
conceal the mechanics of the framing process, although not necessary." It saids
nothing about cutting vents or using screens to keep insects out.
So are we screwing up by exposing the backside of a painting?
 
Didn't we just fight this all out recently? No, sorry, that was whether to glaze an oil or not.

It's generally, although not universally, agreed that a stretched canvas greatly bebefits from the protection provided by a rigid backing such as 4 ply or thicker matboard or polyflute.

It provides protection to the recto from dents, tears and punctures as well as providing a sort of an air cushion to lessen the amount the canvas will move back and forth.

Attaching the backing to the stretcher bars is a good idea, as it will ensure that the canvas will always have the protection, even if it is later removed from the frame.

And please do put a dust cover on it. It makes it look better and will keep bugs and dust bunnies from setting up home. Don't bother with "ventilation holes." A canvas DOES NOT breathe and holes would just provide a nice little entrance for bugs and dust.
 
We work closely with a painting restoration artist. (Conservator) she has confirmed what FramerDave said. I used to do the venting thing until she straightened me out about six or seven years ago. The rigid back is very important, be sure to do it.

John
 
You can also use foamboard with Artcare. The two conservators I heard speak on this topic, one used regular foam board and the other an archival foamboard. Artcare would absorb acids from the paint if it comes through the rear of the canvas, the environment and the stretcher bars. It also is hydroscopic so you don't need to put matboard under it as you would with a polyflut as per the instructions from the Canadian Conservation group..
 
You just gotta love this place. All those helpfull people. I might hang out here for a while... :D

Oops, wife is telling me it's past my bedtime..
thumbsup.gif
 
Have never done this either.
Do I have this right--
1-stretch canvas onto stretcher bars
2-insert into frame
The next step has me confused!

I generally use offset clips to hold the canvas in place--If I cut the mat the same size as the frame, and place it over the stretcherbars,(I am assuming that's where you put it!) wouldn't the clips hold the whole package?
Somehow screwing the mat into the stretcherbars seems strange to me and a little pointless-if using clips--AM I BEING DUMB??

Also I don't know what polyflute is!

Please straighten me out!
oh and Baer--better mind that good woman of yours!!

Elsa
 
Polyflute is a term used to refer to double-wall
polypropylene boards, such as Coroplast or Cor-X.
The material between the skins of such boards comprises small walls, perpendicular to the skins, hence the reference to fluting. This distinguishes it form corrugated board. Corrulite is a polyethylene corrugated board. These boards are especially good for backing canvases, since they have a relatively high degree of puncture resistance. Such a board will damp out vibration, when the canvas is in transit, will help to keep moisture from damp walls away from the canvas, and will keep most air pollution from attacking the back of the canvas. Holes cut in the backing board will only lessen its effectiveness, as the others said.

Hugh
 
I generally use offset clips to hold the canvas in place--If I cut the mat the same size as the frame, and place it over the stretcherbars,(I am assuming that's where you put it!) wouldn't the clips hold the whole package?
Somehow screwing the mat into the stretcherbars seems strange to me and a little pointless-if using clips--AM I BEING DUMB??
No, you're not being dumb. The offsets clips will hold the backing on just fine. The advantage to screwing it onto the stretchar bars is so that the painting will still have the protection if it is taken out of the frame, say for transport or storage.
 
For a complete and correct package, don't forget about lining the lip of the frame rabbet with either felt or volura.

This is especially important for Glicles on canvas as the inks tend to "glue" the painting into the rabbet and whoa be yea who has to defit a canvas from a frame that has not been lined.

When you take in a painting that is framed for reframing, you should also either defit it infront of the customer, or forwarn them about the possibility of damage to the bead area of the canvas from defitting.

Larson Juhl (and others) sells the volura tape. Specialty Tapes (and others) distributes adhesive backed felt on rolls.
 
I would also add to Hugh's post that the edges of coroplast or any fluted board would best be sealed with an archival tape such as Lineco frame sealing tape. The small crevases are ideal places for insects to nest and in the back of the canvas is not being papered, the exposed edges of a fluted board are trouble looking for a place to happen.
 
Rob's idea will give the board a tiny bit more
fire resistance, since all fluted materials burn
well, with their flutes serving as chimneys.
(Something more to worry about)

Hugh
 
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