Bone Folder

A bone folder is a simple, unglamorous tool: a smooth, blunt blade-shaped piece of bone, horn, or plastic, usually with a rounded edge on one side and a pointed tip on the other. It has no cutting edge at all — its whole job is applying firm, controlled pressure without scratching or cutting the material underneath, which makes it useful anywhere leather needs to be creased, folded, or pressed flat without leaving tool marks.

Originally a bookbinder's tool for scoring and folding paper and board, it crossed over into leatherwork because the same qualities that make it good for paper — smooth, hard, non-marring — work just as well for leather. It can crease a fold line, press glued layers flat, open up tight seams and pocket corners, and even do light burnishing in a pinch.

How to use it

1. To crease a fold line, lay a steel ruler along the intended line and drag the bone folder's edge firmly along the ruler's guide, using enough pressure to leave a visible crease.
2. To flatten a glued seam or lining, run the flat or edge of the tool over the area with steady pressure, working out any air bubbles or loose spots.
3. Use the pointed tip to reach into corners — like the inside of a pocket or a folded edge — where fingers can't apply even pressure.
4. For light burnishing, use it the same way as an edge slicker: firm strokes along a beveled edge, though a proper wood slicker will still outperform it for a fully burnished finish.

Care

A bone folder needs almost no maintenance — no sharpening, since it has no edge to maintain. Keep it clean and dry, and if it's made from real bone, avoid leaving it somewhere humid for long periods, which can cause it to warp or crack over time.