Some commercial leather dyes contain pigments that are toxic and should be used only with extreme caution. They can also be expensive. You can make your own leather dye, giving you better control over the color and the safety of the materials, in several ways.
Things You'll Need
Powdered mica pigments
Fine grade steel wool
Strong brewed coffee
Dissolve powdered mica pigment in regular rubbing alcohol. The greater amount of pigment used, the more intense the color will be. Mixing your own dyes from pigments requires trial and error, with frequent testing on scraps of the same kind of leather you want to dye. This method might work best to create small amounts of dye in a non-earth tone color like blue or red, which you can use to paint designs on small areas of leather such as the front of a purse.
Mix two commercial products: leather conditioner and shoe polish. Mixed in equal parts. This solution can be rubbed onto leather, allowed to dry, and buffed into the material. Darker shades can be achieved by repeating the application several times.
Brew some "vinegaroon." Spray fine-grade steel wool with water and allow to rust for several days to a few weeks, rewetting the material daily. When well rusted, put the steel wool in a jar and cover with boiling vinegar. Let steep several days. Longer steeping time and rustier wool will give you the darkest color. Mix vinegaroon with a small amount of commercial leather conditioner to make it easier to apply to leather. Vinegaroon is a good choice for small objects that can be briefly submerged in the dye, such as a leather wallet.
Brew coffee. Strong coffee can be used as a leather dye. Brew the strongest coffee you can, double the amount of grounds you would normally use, then simmer in an uncovered cooking pot to reduce it to one-third its original volume. You can also use leftover brewed coffee, reduced on the stove top, or instant coffee mixed boiled in water. Allow to cool. Mix coffee with a small amount of commercial leather conditioner before applying to leather. Coffee is a subtle pigment, but can revitalize a faded tan leather sofa by giving it a richer brown hue.
Go natural. Red onions can be boiled down to make a shade of blue. You can also make a brown dye from the green outer skin of fresh walnuts; crush the walnut skins underfoot and boil the pigment out of them. Natural dyes will give leather a more subtle color than commercial pigments and are most suitable for doeskin or other naturally pale leathers.
It's easiest to dye leather to a darker shade.
Clean leather well before attempting to dye.
Some homemade leather dyes will leave the dyed article with a strong odor; allow dyed items to dry outside or in a well-ventilated area, away from your living space, until the odor fades.
Never get leather too wet; several light applications are better than one drenching. If you dip an item in dye, such as a wallet, remove it at once and let air dry, then work in some leather conditioner.
Always wear gloves; your hands are made of "living leather" and will pick up the dye, too.
Always work over a protected surface.