Canvas Stretching

Image of stretchingThe purpose of stretching a canvas is to preserve it and prepare it for framing. We stretch a lot of canvases, both painted and unpainted. Depending upon the size of the canvas, we have 5 different sizes of wood stretcher bars we use (light-weight, medium-weight, heavy-weight as well as 1 1/2" or 2" deep "Gallery Wrap" styles). We also believe in using cross bars to prevent canvases being stretched from developing an hourglass shape. Prior to the invention of the stapler, canvases were stretched using copper tacks (they don't rust). Nowadays we, usually, use a pneumatic stapler and can either staple the canvas on its edge or on its back, depending upon how much canvas we have to work with. If the canvas is valuable or the client has a specific preference, we are happy to stretch the canvas with copper tacks. It is a little more labor intensive, since it takes two people to do this properly, so the labor cost is a bit higher.

Inevitably, questions come up about stretching. Here are a few:


How Much of A Spare Edge Do You Need For Stretching And Stapling? We prefer to have at least 1" beyond the amount of canvas it takes to cover the edge of the stretcher bar. That way, we have something to grab with the canvas pliers so that we can stretch the canvas tightly with a minimum of wrinkles. This means we prefer 2-3" from the edge of the painting. In that way, we can staple the canvas on the back. If you are stretching on a 1 1/2" to 2" deep Gallery Wrap stretcher, you will need an extra 2 1/2" to 3" all around.

I Bought This Painting On Vacation In The Carribean And Brought It Back Rolled Up. Any Problem With This? There is no problem with the canvas being rolled up. Hopefully, however, the paint was not applied so thickly that it didn't crack in the process. If the canvas comes in rolled up and stiff, we will warm it up first before unrolling it and stretching it to soften the paint a bit. The most common problem we run into with canvases from The Third World, is that they were painted on stretchers that were not square to start with, on canvas that may be something as inexpensive as bedsheets, curtains or spare fabric that have been gessoed over. In addition to not being square, they may not have left you much on the edges to re-stretch the canvas. We will not build a crooked stretcher, however, to restretch the canvas. It becomes unframeable because of that issue. If they have cut off the extra canvas on the edges, we can mount the canvas to an acid-free board  and trim it square so that it can be framed.

How Big A Canvas Can You Stretch? Typically, the longest, heavy duty stretchers we build can be just under 10 feet long. We buy heavy duty stretcher bar in 10 foot sticks. You must allow for miters at the corners, so the stretchers cannot be 10 feet long. However, remember that there are logistical problems with a canvas that size, such as getting it through a doorway and transporting it, usually requiring a straight truck with a big box on the back of it. In some extreme cases, we have gone so far as to stretch the canvas on-site, since it cannot be transported any other way.We have stretched canvases in excess of 20 feet, but only on-site using hybrid wood and aluminum stretchers from Jack Richeson & Co. They have splicing panels and crossbars made specifically for daisy-chaining long runs of stretcher. They also have corner bracing hardware for keying out the corners when needed. Contact us for a quote if you have a special, oversize canvas project.

Why can't I just build my own stretchers out of 2 x 4's? You can, but the problem is that stretcher bars are shaped especially, so that the canvas only rests on the rounded outer edge, with the main, flat portion falling away and tapering in thickness so that the stretcher doesn't touch the back of the canvas. Over time, if it does touch it, a line begins to appear in the painting. So, unless you are handy with a lumber milling machine or an electric router to make your own stretcher bar from scratch, we recommend you let us do that for you. For some clients, we cut the stretcher bars, when very long, and bring them on-site and stretch the canvas there for them. However, they pay a lot more for that privilege, including travel time.

What's the difference between a Stretcher and a Strainer? The kind of wooden stretcher bars you buy in an art supply store that have slotted grooves and flat fingers that slide into them are what most people are used to finding on pre-stretched canvases. Typically, they come in whole inch sizes and allow you to expand the corners later on if the corner loosens up. However, a lot of canvases that come into our shop from Europe, Asia and other places outside the USA are in metric or non-standard sizes. In those cases, we build what is called a strainer, which is a stretcher with permanently glued and nailed corners. However, if the client requests it or it is an antique canvas that requires it, we can order in custom-sized, basswood stretchers with slip-together keyed corners from a manufacturer in San Diego that does beautiful custom milled woodwork. Again, this is way more costly than a strainer or standard-sized stretchers but worth it in many cases.

Is It Expensive To Stretch A Canvas? No, it is not expensive, relative to what it will cost to frame it. We charge for the stretcher bar it is going to be attached to and the amount of labor it takes to staple it onto the stretcher. It is somewhat labor intensive, but the canvas looks great once it is attached, all smooth and taut. Like frames, bigger canvases take more time to stretch and cost more than smaller ones. The main point here, though, is that it must be stretched before it can be framed. In a few minor cases, we have (with the customer's permission) dry mounted  the canvas to board and framed it with mats under glass. However, this is fairly rare.

Some of the time, people will call for quotes and then tell us that " I have gotten other quotes somewhat cheaper from other framers and you are a little high." Our answer is that you get what you pay for. We are experts at what we do and have decades of experience and PPFA certification to prove it. Also, we cannot speak to what the overhead costs or expense structure is for other framers, so we really cannot price our services according to what it costs other framers to do business. Our prices are fair, very competitive, but reflect what we need to charge to stay in business.

Once You Stretch It, What Sort Of Frame Should I Use? You have at least 4 really good options to start:

One way is to frame it in what is called a Floater Frame. This is an "L" shaped frame profile that does not have a lip to cover the edge of the canvas. The canvas is attached with screws to the bottom face of the "L" in the floater. It can be attached with a gap of 1/4" to 1/2", giving the appearance of the canvas "floating" in the middle of the frame, or the canvas can be snug, up against the edge of the floater. Either way, the edge of the canvas is never covered up by the frame. Our rule of thumb for pull-away goes like this:  1/4" pull away for canvases up to 36 x 48, 3/8" pull away for canvases larger than that. If the canvas is already stretched and is not square or perfectly symmetrical, a bigger amount of pull away is recommended to minimize the visual impact that the lack of squareness will have.

A second option is to frame it with a standard wood frame that is deep enough for the stretcher bar used. Here, the lip of the frame will cover the canvas a little bit, usually no more than 1/4". Normally, in preservation framing, we will seal the inner surface of the frame where it comes in contact with the canvas, to prevent acid from seeping into the canvas from the wood of the frame. It also prevents the painted surface of the canvas from sticking to the frame where it makes contact. To do this, we use a narrow, foam-like tape called Volara on the back of the frame lip. Then, we use an aluminum backed, acid-free paper tape to seal the inside of the frame's rabbet (the part of the frame under the lip). 

The third good option is to use the second option, but add a fabric covered "liner" in between the frame and the canvas. The Liner acts like a mat does in a regular matted frame job. It creates a visual separation between the art and the frame. It costs more to use a frame and a liner than just a frame but, if done right, is very effective in enhancing the overall design of the framing. The only down-side to liners is that, unless there is glass covering the liner (between the outer frame and the front of the liner), the liner will, over time, absorb dust, dirt, environmental pollutants and change color. Sometimes, we will stack another frame inside the main, outer frame in lieu of a liner.This prevents the discoloration problem over time, but still allows you to place a layer of glass or pexliglass in between the two frames, protecting the canvas from pollution and u/v fading.It also allows for more interesting color and design options and visual effects.

Lastly, the fourth option is not to frame it at all. Canvases stretched over Gallery Wrap bars (1 1/2-2" deep) usually have additional painted or printed surface covering the vertical, outside part of the canvas. In this way, you do not see the white unpainted/unprinted part of the canvas and it can hang on the wall just like that. This has become fairly popular with people who either do not have the money to invest in a frame right away or who prefer to view the canvas without the additional visual weight of a frame.  As framers, while we lament the use of this method, we realize that this is just the way it is these days. We will be happy to add wire and wire hangers to the back of the stretcher if you wish to hang it up unframed. We can also dispense with wire and put a pair of D-rings on either vertical member of the stretcher to let you hang the canvas from two hooks. This is especially recommended if the canvas is large. You just have to be sure your two hooks are at the precisely same height off the floor and level, as there is no way to adjust them, other than to pull the nail and hook out of the wall and move it or to unscrew the D-rig and move it up or down.. 

Should I Put Glass Over My Canvas When Framing It? No, you do not need to use glass when framing painted canvases. With a painted surface on a canvas, the paint seals the fabric and prevents deterioration of the fibers. However, more and more people are using glass, in conjunction with a fabric liner, putting the glass between the lip of the frame and the top of the liner. A fabric liner is, essentially, a wooden frame that has been covered in fabric and then stacked inside the lip of the outer frame. Visually, they serve the same purpose as a mat does when framing works of art on paper. If you do not wish to use a liner, we can put acrylic spacers on the outer edges of the glass, which are hidden under the lip of the frame. They will, then, rest on the outer edge of the canvas. One warning, thoug: Be sure the painting is completely dry, especially if it is an oil painting or has been varnished.

One trend we have found is that people are using OP3 (u/v filtering plexiglass) over their canvases to prevent fading. Others, who are less concerned about cost, have had us use Optium Museum Acrylic, which has all the attributes of Museum Glass and is scuff resistant and does not shatter like glass. It is also way pricier, but virtually invisible and weighs half of what glass weighs. Museum and AR glass look terrific when used in this context, as they are nearly invisible and UV protective. The glass would serve as a barrier to environmental pollutants, dust, sharp objects, and UV light.Glass is heavier than acrylic or plexiglass, but does not scratch as easily nor is it eletrostatic (which attracts dust, except for Optium, which is not electrostatic).