USING THE PIT BULL » Gallery Wrap Stretching – Pit Bull Wrap Stretcher

How to use the Pit Bull Wrap Stretcher

These instructions may also be downloaded as a PDF at this link >>>

Do not attempt to use this product until you have read and thoroughly understand these operating instructions. This tool is only for the intended use for which it was created: to stretch art canvas. Do not clamp the tool down on any other surface as this could result in personal injury and may damage the tool. Always work safely and be aware.


This is a steel, precision-machined tool, and should not be dropped on the floor or any other hard surface. Doing so will result in the misalignment of the jaws of the locking pliers and the tool will not function properly. It is recommended that the user work in an area that has sufficient room to stretch and rotate the canvas without knocking the tool off the working surface. When storing the tool after use it is best to always leave it in the locked position.


The Pit Bull Wrap Stretcher™ will give you the ability to quickly and effortlessly stretch your own gallery wraps. The following instructions will guide you step-by-step on how to use this amazing tool. The Pit Bull Wrap Stretcher™ has no limitations on the size or type of stretcher bar used. In addition to gallery wraps, The Pit Bull Wrap Stretcher™ can also be used to stretch canvases with stapling on the side.


Before beginning to stretch your canvases, you’ll need to adjust the tension screw on the Pit Bull’s locking pliers. First, snap the jaws firmly into place. Adjust the tension screw as shown in Fig. 1 and then snap the tool shut as shown in Fig. 2. The tool should lock into place with just a slight amount of resistance. When you close the tool onto the canvas, you may need to adjust the tension depending on the thickness of the material. Ideally the jaws will snap firmly down on the canvas without being too difficult to open for the next stretch; you want to achieve a smooth work flow. Once you become adept at using the Pit Bull, you will easily find “the sweet spot” on your tension setting. You will also become familiar with the type of canvas that you work with and this will enable you to achieve the correct tension setting. Remember not to go any farther than necessary on the jaw tension so that the locking pliers open quickly and easily. If you notice that the grasping pins are tearing slightly at the canvas when you are stretching it means that you need to adjust the tension screw a bit tighter in order to better grasp the canvas.


The Pit Bull will easily gallery wrap on any type of stretcher bar. The amount of canvas that you need extending beyond the inside of the stretcher bar is three quarters of an inch. For example: if you are stretching on a standard three-quarter inch thick stretcher bar, you add three quarters plus the width of the bar which is typically one and a half inches. To this amount you would add three quarters of an inch which would give you a total of three inches. Accounting for both sides you would double this number which would mean that your total extra canvas beyond the image size would be six inches. Using this formula for gallery wrapping an 18×24 inch frame, you would need a canvas size of 24×30 inches. If you’re ever in doubt about the amount of canvas you’ll need, it’s always better to go slightly larger to avoid any problems.


It’s important that you begin stretching with the tool properly positioned. Fig. 3 shows the tool with the jaws open, resting lightly on the stretcher bar ready to grasp the canvas. Fig. 4 shows the tool locked in position grasping the canvas. Notice how the starting position for the tool has the jaws at a 90 degree angle to the stretcher bar. Finally, in Fig. 5, be sure to position the fulcrum (the fulcrum is the pivoting point on the bottom jaw) so that it is touching the inside of the stretcher bar. Once you have the tool in this position you are ready to begin stretching.


The first thing you’ll notice when you stretch with the Pit Bull is that it doesn’t take any hand strength to achieve an incredibly tight stretch. This is because the grasping pins combined with the locking pliers do all the work for you. Once you become familiar with how little effort is needed to stretch your canvas, you will be able to easily gage how much pressure to apply. The Pit Bull will allow you to stretch canvas without any hand fatigue. Fig. 6 and Fig. 7 show the Pit Bull stretching the canvas. The Pit Bull is designed to lay the canvas down flat against the stretcher bar so that the staple can be driven in all the way every time.


Fig. 8 and 9 illustrate a very special function of The Pit Bull. You will notice that the tool has a notch on the bottom jaw on either side of the fulcrum. If you look closely at Fig. 8 you will see how this notch allows you to grasp the canvas on top of the stretcher bar and pull it tight. This is an important element of the tool for several reasons. First, it allows you to tightly stretch the canvas on top of the corners. Second, it allows you to stretch over center and forty five degree supports on larger stretcher bars. Finally, after you have prepared the corners for wrapping it allows you to easily pull the corners very tight and make them look beautiful. This is illustrated in Fig. 9. Now, with the Pit Bull, completing the wrapped corners becomes a simple and effortless task.


The technique for stretching canvas has traditionally been done by starting in the middle with one staple, going to the opposing edge with another, and repeating this process on the other two edges. The problem with this technique is it can cause wrinkles in the stretched canvas. The technique for stretching described below will not only eliminate problems with wrinkling but will also greatly speed up your production output. This technique was developed many years ago by one of the leading suppliers of stretched canvas on the West Coast, Art’s Canvas, whose owner is one of the co-inventors of the Pit Bull Wrap Stretcher™. Though at first glance it might seem contrary to what you already know, this technique has been proven over the course of 40 years and millions of canvases stretched. You can watch an instructional video of this stretching method in action visit our website at: The following is an explanation for stretching a printed canvas giclée. Stretching raw unprinted canvas uses the same method without the need to center the print on the stretcher bars.

Step 1: With the print face down on a soft padded table, lay the stretcher bars down on the canvas and wrap the printed image over the edges of the stretcher bar. Move the stretcher bar around until the printed image is centered on the bars. Start working on the short edge first. Once the image is centered all round, you’ll need to cheat the starting edge over slightly to account for how much the Pit Bull will stretch the opposing edge. This amount will vary according to the type of printing canvas that you are working with.

Step 2: Begin by putting a staple in the corner nearest you as shown in Fig.10. Then grasp the canvas on the other corner as shown in Fig. 11 and pull away from the staple that is already in the wood. Once you have tension pulling on the existing corner, shoot the staple in the opposing corner. It won’t take a lot of tension, just pull it tight with your thumb and first finger.

Step 3: As shown in Fig. 12 you can now staple the entire short side.

Step 4: You can now stretch and staple the opposing edge as seen in Fig. 13. Do a quick check by wrapping the image around the back of the stretcher bars once again to make sure that the image is still centered on the long edges before you begin stapling.

Step 5: Trim the canvas off the two short ends with a box cutter and straight edge. You can mark the inside edge of the stretcher bar by creasing it with your thumb, and then placing the straight edge in the center line between the staple and the crease mark. Since you can only use the box cutter and straight edge on the stretcher bar, you will want to complete the cut with a pair of sharp scissors. A good technique to use while you are cutting with the straight edge and box cutter is to always remember to apply pressure with the hand that is holding the straight edge at the point where you are cutting. You will need to walk your hand down the straight edge as you are cutting. This is illustrated in Fig. 14 and you can see it in the instructional video on our website. This will keep you from slipping while you are cutting, and avoid damaging the print and your hand.

Step 6: Starting in the center of the long edge, shoot a few staples in with just a small amount of tension on the stretching tool as shown in Fig. 15. You don’t want to apply much pressure at this point as the opposing side is not yet stapled down and you will pull the image off center. Once this is done, you can flip the canvas around and stretch and staple the opposite edge. When you are stretching with this method you should only apply full pressure to complete the stretch when the opposing side is stapled down as shown in Fig. 16.

Step 7: Fold the corners and prepare them to finish off the gallery wrap. There are a number of techniques for wrapping the corners. The demonstration video on our website shows an effective way of doing this.

Step: 8 Refer back to Fig. 9 to see how the tool makes it simple and easy to complete a tightly-wrapped corner every time.


Sometimes, when stretching raw canvas on which you are going to paint, you may want to remove the canvas and restretch it again later. For wrapping the corners with the extra canvas intact, you simply slit the canvas as shown in Fig. 17 and complete the wrap as previously shown in Fig. 8. Fig. 18 illustrates how by slitting the canvas you can position the fulcrum to complete the gallery wrap without trimming the canvas. It is best to leave the extra canvas intact inside the corner when using this method. This will make it easier to restretch the canvas later. This is demonstrated in the video on our website and appears at the end of the demonstration.

Watch the instructional video for more in-depth demonstration on how to use the Pit Bull.
These instructions may also be downloaded as a PDF at this link >>>


Our Warranty


What is covered: This warranty covers any defects in materials or workmanship for a period of six months from the date of original purchase. To obtain repair or replacement under this Warranty, the tool and copy of the original dated receipt must be returned, freight prepaid to Grayfeld, Inc. Call us for the correct address.

What is not covered: This Warranty does not cover damage by misuse or abuse of this product. It does not cover the misalignment of the jaws which result from dropping the tool on the floor or any hard surface. Any representations or promises inconsistent with or in addition to this warranty are unauthorized and shall not be binding upon Grayfeld, Inc.


Patent Number: 8,495,828
© 2013 Grayfeld, Inc.