Burnishing

Burnishing is the process of rubbing a cut leather edge, usually with a wood or bone tool, canvas, or a wool wheel, until friction heat and pressure compress and smooth the raw fibers into a rounded, glossy finish. It is typically done on veg-tan leather after the edge has been beveled and dampened.

The process works because heat and moisture soften the natural collagen in veg-tan leather just enough for the loose fibers to fuse together under pressure, sealing the edge and giving it a polished look that also makes it more resistant to fraying over time. Chrome-tanned leather generally does not burnish well because it lacks the same fiber structure and tannin content.

A slicking agent like gum tragacanth, saddle soap, or plain water helps the tool glide and speeds up the process, and working in short, even strokes over the whole length gives a more consistent shine than pressing hard in one spot. A common mistake is burnishing an edge that has not been beveled first, or trying to burnish leather that is bone dry, both of which leave a dull, rough result instead of a glassy one.