Virgin leather always starts light in colour and finishes darker. Moisture of any kind including oil will darken leather. Natural sunlight will tan leather as it does when it is still skin. The original colour of the leather is dependant on the animal, cut and tanning process. There are several ways to manually colour leather, for the purpose of keeping things short I will stick to talking about our own process. Dying and painting are common and we use water based colouring dyes, the water acts as a carrier, the leather soaks up the water mixed with the dye pigment. The pigment is left behind after the water dries. The leather is then polished to a shine using wax that is either clear or coloured. This helps to seal the leather. Sealing products can also be used but we have found the polishing works best. When the wax is applied it will make the leather darken and usually it will give a uneaten look. Then when it is brushed in and polished it will even put to a uniformed finish.
Prior to polishing the colour is lighter and a mat dull finish.
Unfortunately the leather is effected in the dying process and becomes quite stiff when dry, we soften the leather again by manually bending the leather, This loosens the fibres making it soft again, this is usually done by running it over a bend such as a smooth round timber the diameter of a common broom handle or just with the hands.
We don’t oil leather but we do condition it and this darkens the colour. A lot of care is required when this is done as it can cause colour blotching and an uneven look. To much conditioner is not good and can have a damaging effect like over oiling will.
Matching colours takes a lot of experience and an extended amount of time because time is required for the leather to dry between coats and only dry leather reveals the finished colour and soaked leather stops absorbing colour pigment.
Painting leather is reserved for non traditional colours and some edge sealing. Leather paint is available but with experience other paints can be applied with good success. We use leather edge dyes and paint on some edging but never on the top surface. Top surface is always natural or dyed.
When the wax is applied it will make the leather darken and usually it will give a uneaten look. Then when it is brushed in and polished it will even out to a uniformed finish.
I hope you have enjoyed the post and please ask if you would like further information.