With gel medium, you can transfer an image to any surface that the medium will bond to. This includes paper, wood, metal, plastic or fabric. However, some surfaces work better than others. Smooth surfaces accept transfers while rough surfaces are problematic. Wood, for example, must be extremely well-sanded because its surface is so uneven in its natural state. Also, tightly woven fabrics accept transfers while loosely woven cloth may not. Similarly, images will not transfer properly to rusty metal, but you can transfer successfully to pieces of smooth metal.
Not all images will transfer effectively. For example, you will probably be unsuccessful if you try to transfer anything printed on photographic paper. Postcards are also unlikely to work. However, photocopied images generally produce good results, so if you would like to use a postcard or photograph, simply photocopy it first and transfer the copy. Images from magazines and newspapers generally produce good results.
When you are applying the gel medium to a picture, make sure that you begin the process from the center of your image and then work the medium outward. You will be able to smooth the paper as you work so the image will be less likely to wrinkle or tear. If you apply the medium on the edges and then work it inward, the edges may fold and it will be more difficult to keep your work smooth. Also, you must completely cover the image with the gel medium. If it is not entirely coated, the uncovered parts of the image will not transfer.
When transferring images, it is extremely important to avoid air pockets. This is because air pockets prevent the part of the image that is above the air pocket from directly touching the paper. The result will be parts of the image that will not transfer at all. One way to prevent air pockets is to burnish the back of the image with the back of a metal spoon as soon as you place it face down on the paper. This way, you can flatten wrinkles and air pockets. Another method of eliminating air pockets is to use a small brayer. Beginning at the center of the image, carefully roll the brayer over your work, eliminating air pockets and wrinkles as you go.