It is used to refine crude oil in the production of petroleum jelly.

In the 18th and 19th century, bone char mixed with tallow or wax (or both) were used by soldiers in the field to impregnate military leather equipment, both to increase its lifespan and as the simplest way to obtain pigment for black leatherwares.
 Military and civilians used it as shoe polish and preservative, including on shoes with the "rough" side out.
 In period reference materials, it is referred to as "black ball".

The ESA-NASA Solar Orbiter satellite uses a refined form of bone char which is applied to its titanium heatshield.
This protects it against the glare and heat of the sun.
The coating was developed by Irish company Enbio and uses its 'CoBlast' technique, originally developed to coat titanium medical implants.
It is used to refine crude oil in the production of petroleum jelly.
In the 18th and 19th century, bone char mixed with tallow or wax (or both) were used by soldiers in the field to impregnate military leather equipment, both to increase its lifespan and as the simplest way to obtain pigment for black leatherwares.  Military and civilians used it as shoe polish and preservative, including on shoes with the "rough" side out.  In period reference materials, it is referred to as "black ball".
The ESA-NASA Solar Orbiter satellite uses a refined form of bone char which is applied to its titanium heatshield. This protects it against the glare and heat of the sun. The coating was developed by Irish company Enbio and uses its 'CoBlast' technique, originally developed to coat titanium medical implants.
Bone char