Leather burnishers and slickers are usually rounded or curved tools used to burnish (smooth-out) leather surfaces and edges through friction. Since leather is a natural fiber that has been processed to have a smooth and even finish, when it’s cut, the edges will show the internal fibers and often be loose or “hairy” as the fibers stick out.
To help ensure a finished leather product that can wear well and be durable, it is generally good practice to smooth out, or burnish, the edges. This makes them hardened and strong. Sometimes, edges are even painted to seal them up. Many preferences and options are available for this, though burnishers and slickers are often used most.
They come in different materials ranging from plastics to exotic woods. There are hand burnishers, where you move it back and forth over the leather by hand it generates heat through friction and changes the leather surface.
There are also burnishing tools that use motors to rapidly move the burnisher over the leather to seal the edge. Burnishing machines and attachments make this a very easy task, and include dedicated machine as well as attachments that fit onto drills and rotary tools.
The key to burnishing is heat generation and transfer. When the edge leather fibers are heated they join together and smooth out. So friction created by moving a burnisher back and forth quickly makes this happen. When choosing a burnisher material, keep in mind the different heat properties of the material.