Dyeing leather fabric is a project you can complete successfully in less than a day. The method is the same whether you're dyeing a piece of leather for sewing or crafts, or a finished garment or accessory. All you need is dye that's intended for leather. A surprising difference between dyeing leather and other fabrics is that with enough coats of dye, you can use any shade of leather dye on any color leather.
The most essential supply for dyeing leather is leather dye, which is formulated specifically for the job and is available at online leather product websites and some crafts and fabric stores. Leather finisher, which seals the dye, is useful for this project but not essential. Some finishers also add a shine to the dyed leather. Use clean sponges or rags that you already have around the house to apply leather dye, or purchase a special wool dauber, which is a pad of wool attached to a handle that you use in the same way as a paintbrush. A paintbrush is also handy for applying dye to fiddly parts of leather garments and accessories. Find a drop cloth to protect your surfaces. You will also need rubber gloves, old clothing and an apron.
Unless your leather is brand new, clean it before you begin dyeing. Surface grease and grime will interfere with the application of the dye. Use baby wipes, leather cleaner or acetone. If you are dyeing a leather item that includes seams or hardware, such as buckles on a bag or zippers on a jacket, cover these parts with tape to protect them from the dye. Take your leather fabric and supplies to a well-ventilated area and lay down a drop cloth to protect your surfaces from the dye. If you work outside on a warm day, the drying time will be quicker than if you work inside.
The application process for leather dye is quite simple. Dampen the surface of the leather with cold water. Use a sponge or rag and aim to dampen -- not saturate -- the surface. Apply the dye with a second clean sponge or rag, or dauber. Rub the dye onto the leather using a circular motion until you've covered the whole surface of the leather. Start with a small amount of dye and adjust the saturation as you see fit. Use a paintbrush to apply dye to hard-to-reach areas. Don't worry if the color isn't to your satisfaction with just one coat. You may need to apply two or more coats of dye to get the color you want. Let each coat of dye dry completely before applying the next.
After the final coat of dye is dry, buff the leather with a clean, dry rag to remove any excess dye. Apply a fine coat of leather finisher with a clean, damp sponge or rag, following the manufacturer's instructions. This prevents the dye from transferring onto other materials.