Using a creaser is one of the easiest ways to impress a solid black line in leather. Simply dampen the leather overall, score a line with a bone folder and straightedge, then rub the creaser back and forth. Or some prefer to score a straight line on dry leather, wet the line with a small brush, then use the creaser. The lines I made in the images were done with a room temperature tool, though with some leathers a darker line develops if used warm — but not hot.
The design of this creaser is based on an early 20th century Frederick Westpfall tool in my collection. You can burnish the line you make by “jiggering” it back and forth, increasing pressure as it forms a groove. The burnishing gives the dark blind line a sheen. Once a basic depression is formed, the creaser slides like a cross country ski in a groomed track. The length of the handle allows for two-handed use to apply extra pressure, and you can even lean into it a bit with your shoulder.
The resulting blind line is flat on the bottom and reflects light evenly, unlike marking leather with a bone folder or other irregularly shaped object. Since the tool is usually used at ambient temperatures or only slightly warmed, there is no risk of burning the leather.
The thick maple handle is easy to grasp with one or two hands, and lean into with your shoulder. Overall length is about thirteen inches. Brass head with maple handle.