Optional materials
gesso (to prime the transfer surface, though you may also prime a paper surface with acrylic medium), screen printing squeegee, x-acto knife
Transfer Process
1. Begin with either a black & white or color photocopy, on plain paper. (Laser prints will also work. Ink jet prints will work, but about 30% of the ink will come off after you scrub, resulting in a fainter image.)
Note: For canvas transfers, make the photocopy image 1/2 inch larger than the transfer surface in each dimension. For example, if you were transferring to a 10 x 10 inch surface, the original image would ideally be 11 x 11 inches. When transferring onto a piece of paper, we transfer onto a large piece of paper and then cut the image down, so there is no need for the larger image on paper transfers. Just make sure there is about an inch of blank paper on each side of the image. If you don't have that extra paper, tape extra paper to the sides. This extra area will make the scrubbing much easier.
2. Staple the photocopy, print surface up, to a flat surface. This prevents the paper from wrinkling from the expanding and shrinking process the paper goes through while wet and drying. Just put one staple in each corner, about 1/4 inch from the edge.
3. Paint 2 or 3 layers of acrylic medium onto the print surface of the photocopy (you may also use gesso to transfer, and it works perfectly fine, but you receive a fainter image, and the darks are not as dark as they are with the acrylic medium transfer. You may also use colored acrylic paint.). Allow each layer to completely dry before applying the next. Speed up the drying process by using a fan and heat if cold. The two key ingredients for the fastest drying acrylic paint is warm, moving air. If you are using thick gel medium, water it down for this step. It will make the brush strokes less noticeable.
Note: You can completely avoid this step and transfer the original photocopy to your surface. This step helps create a more reliable and precise transfer. The layers of dried medium make it less likely any air bubbles will tear off while removing the paper. It also makes the paper less likely to warp or ripple while drying. If you want a more deteriorated and unpredictable transfer, skip this step.
4. While the layers of medium are drying, prepare your transfer surface. If you are doing a straightforward transfer onto raw canvas or other surface that takes acrylic paint and you want an accurate reproduction of your original image, gesso the surface. The white in the photocopy is the white of the paper, so an initial white surface will recreate this. As for paper, use a larger sheet that you will eventually cut down (we often do multiple transfers on a large piece of paper).
5. Now, you are about to attach your image to your transfer surface. We recommend using either wood or canvas your first several attempts. If canvas, either attach the canvas to a wall or table (unstretched) or build a plywood surface the size of your actual stretcher and stretch the canvas to this surface. We use this method because the pieces are mobile and because removing the paper in the next steps is easier on a table surface. For a paper transfer, have the large piece of paper attached to a wall.
6. Once the layers of medium are dry, apply a thin layer of water with a spray bottle or a brush to your paper still hanging on the wall. You don't want the image soaked, just damp. This step allows the paper to expand a little. While the paper is still attached to the wall, just give it a few sprays and rub the water in with your hand. Let it stay damp for 30 seconds. If you skip this step, the paper has a chance of forming ripples in the next steps while drying to the transfer surface. Also, if your last layer has just dried in the past few hours, there will likely be enough moisture in the paper already to avoid this spray step. But it is safest to make sure its damp before transferring. Apply a layer of medium to the surface you are transferring to and then place your image, face down (face down is with image that you have painted down onto the surface, into the wet paint, with the unpainted side of the paper facing up).
7. Gently place your image on your transfer surface and align your edges. You are basically going to gently apply pressure and move from the center of the image to the edges, forming a strong bond between the transfer surface and the photocopy, as well as removing as many air bubbles as possible. Only work the air bubble out in one direction, either horizontally or vertically across the surface of the paper (in other words, work the bubbles out either from center to top and bottom, or center to left and right side.) Be gentle, you can tear or distort the paper pushing the air bubbles out, especially if the paper is wet or if there is humidity. You can use your hands, but we always use a screen-print squeegee for the most uniform results. On large transfers (over 20 inches in both directions), the squeegee is essential. You can also remove air bubbles by taking an x-acto knife, cutting a small 1/4 inch slit in the middle of the air bubble, and pushing the air out the small hole. Often times, while removing air bubbles, several will connect and form a large air bubble, which is a good time to use the x-acto knife. If you are transferring to paper, attach the paper to a wall once the air bubbles are removed. This keeps the paper from wrinkling during the drying process.
8. Let the paint completely dry. The transfer will dry fastest in hot, dry environments and slowest in cold or humid environments. You will be able to feel moisture on the back of the photocopy paper, as well as feel the softness of the drying paint when the transfer is still wet. 24 hours is a safe dry time. Be sure to use a fan while drying the transfer. This keeps the paper from wrinkling during the drying (the wrinkled paper is a great effect, so you may also want to take advantage of it.... if this is the case, do not wet the paper before you transfer, the wrinkles are caused by the paper expanding when wet, as well as moisture sitting on the surface of the paper while drying. To get a lot of wrinkles, transfer your original photocopy without any of the preliminary layers of medium.)
9. Once the transfer is dry, take a spray water bottle and wet the paper. Take any type of stiff-bristle brush. We use a plastic brush that is about 4 inches long, has a handle, and 2-3 inch plastic bristles.
10. Scrub the wet paper. This is why you need a resistant surface, you simply can't do this step on a stretched canvas. You begin with heavy scrubbing and, as you remove the layers, begin scrubbing more delicately. Scrub a layer, wipe off the paper, spray, scrub again, wipe off, spray paper, take an old t-shirt and get the small particles left behind. Finally, just barely wet the paper and use your fingers to get any tiny bits of paper left behind. You want to remove all of the paper. On a small 10 x 10 inch transfer on canvas, it typically takes about 15 minutes to remove all of the paper.
Note: You can remove the pigment while scrubbing the paper. You may want this, it creates a weathered effect. Also, if there is still moisture in the paper, the pigment will scrub off easier, so for instance if it is humid or if you have perhaps let the transfer only dry for several hours, there may still be moisture. Just be careful while scrubbing. Or, if you want the weathered effect, then take advantage of this.
Troubleshooting
Air bubbles - Large air bubbles can dry under the surface of the photocopy, preventing the acrylic medium from drying to the surface in these areas. You can save these areas from rubbing off by being very delicate. The initial layers of acrylic medium act to prevent this.
Scrubbing pigment off - You can scrub the pigment off by scrubbing too hard. You may also be scrubbing the paper off too soon, while there is still moisture in the drying paint. This is a nice effect, so you may use it to your advantage.
Textured surfaces - Problems occur on textured surfaces, where a certain area of the transfer is more worn in the paper removal process. Avoid this by being very careful, maybe not even using the brush in the problem areas, but rather either a cloth or your hands.
Paint flexibility - The flexibility of dry acrylic paint is much higher in warm environments than cool. Pigment is more likely to rub off when the room temperature is 80 degrees or above.
Shrinking paper - Under extreme heat (on a radiator or next to a heater), the paper will slightly shrink while drying. This is especially a problem when multiple images are taped together, making a larger image. What were seamless, taped pages (the tape is on the back, dry side of the paper) can dry with up to an 1/8 inch space between the pages. Allowing the transfer to dry under normal conditions with a fan is the best way to avoid this problem.
Photos of a Paper Transfer

1. The mirror image of the transfer image stapled to the wall. It is a regular color photocopy on 11 x 17 paper. The paper being used to transfer onto is 80 lb Strathmore paper. An excellent paper we use almost exclusively now is Utrecht American Masters 250 GSM (Natural color, which is a yellowish off white). A somewhat heavy paper is necessary, around the weight of card stock. Both pieces of paper have 2 layers of acrylic medium.

2. A smooth surface to attach the two pieces of paper. A layer of acrylic medium is painted onto the paper and the photocopy is placed face down. The air bubbles are removed with the squeegee. Once this is finished, reattach the image to the wall to dry.

3. This is the image after it has dried for 24 hours. It has been sprayed with the water bottle, about to be scrubbed with the brush.

4. Scrubbing with the brush, to get rid of the thick paper. This is the hardest scrubbing. You will be removing big pieces of paper. Keep your brush wet, either by spraying the paper or by dipping the brush into a bucket of water.

5. This is the more delicate part of the transfer, removing the smaller pieces of paper. Old cotton t-shirts work very well.

6. Use the t-shirt to dry the paper (you don't want it completely dry, wipe up all the standing water) and remove the very fine pieces of paper with your fingers. You can see the paper, but most importantly, you can feel it with your fingers. The removal process for a transfer this size on paper takes about 15-20 minutes.