I'm going to tell you a short story.
I remember when I purchased my first round knife, I was really keen to try it out. I had first seen its use by a leatherworker in Canada who taught me the basics of leatherwork and case making.
He would strop the knife against a firm scrap of hide covered in polishing compound and as he swung the blade rhythmically back and forth, you could hear the metal singing between each stroke whilst seeing the flash of polished steel as he made quick work of sharpening that blade.
He would always test the edge by running it lightly over the dark hairs of his forearm to confirm its readiness to cut. I can still hear the faint ‘ting’ as the hairs popped off before he’d smile to himself.
Afterwards he would place the blade down onto the leather and push forward along a previously marked line. I remember thinking how the knife seemed to glide effortlessly through the hide as if it wasn't even there.
He was a grumpy old bastard (which is odd for a Canadian I can tell you) and he didn't ever share his tools with anyone.
If you didn't have the right tool with you, best go and buy it from the shop out front (smart marketing..).
Needless to say, I never got to cut leather with his round knife.
But what I didn’t realize at the time was that not all round knives come with 30+ years of sharpening experience at the apex of the blade. Not only that, but there was more to it than a sharp blade and a skilful hand as I was about to find out.
Fast forward to my first round knife experience back in England. I’d just received my order of a George Barnsley round knife in the post.
It was as blunt as a butter knife with a ‘serving suggestion’ of a bevel that offered an edge about as sharp as a Primark suit.
An hour later I had made a consistent fifteen degree bevel on each side and polished it to perfection, just like the round knife I first saw being used.
I tested the edge against the hairs on my forearm, and to my delight I heard the tell-tale ‘ting’ once more as the hairs drifted to the ground.
Setting up a piece of leather against my green cutting mat, I placed my razor sharp knife down and began to push the blade into the leather.
I could feel my hand shake under the pressure as I cut - this was hard! Something didn't seem right. The blade wasn’t cutting smoothly at all, it wasn’t ‘gliding’ through the leather like I remembered seeing. What on earth is happening?
Before I explain what was going wrong, let’s talk about cutting surfaces and how they can make or break your leather cutting experience.
Sometimes picking the right surface to conduct your leatherwork can be tricky, there are many people using many different mediums.
From self healing cutting mats, kitchen cutting boards, wood, various plastics and even sheet zinc (surprisingly good!).
So, which is best for your cutting needs?
Let me take all the hard work out of the equation for you and simply tell you what I have found to be the ideal leather crafting cutting surface after testing various options.
As one of the hardest engineering plastics, it prevents any blade from penetrating far into its surface.
That’s just one benefit however, the other very important factor is low surface friction.
This means your blade slides along the surface like an Olympic ice skater, leaving minimal marks on the surface to scratch your work.
A similar material is DuPont’s Delrin® (acetal homopolymer). Nearly the same properties, slightly harder, eye wateringly expensive (at least for cutting things on).
Acetal copolymer isn’t exactly cheap either, but one sheet at least 10mm thick should last you a lifetime of use. I use a 610x1000mm sheet of it.
After comparing various possible cutting surfaces (that I knew I could buy in large sheet form), I found that nothing came close to acetal for all parameters. For more information on what those parameters were and what materials I tested, watch the video below:
So going back to my original story, what was the issue I was having when pushing my round knife through leather?
Well, as I mentioned, I was using a self-healing cutting mat. For pull cuts (cutting towards yourself) self healing mats are ok, but pushing allows your blade to sink into the relatively soft surface further gripping the blade.
This greatly increases friction and thereby the effort needed to drive my round knife forward with ease.
Switching to acetal copolymer (and getting a better round knife!) made all the difference.
I don’t actually know what that old Canadian leathercrafter was using as a cutting surface all those years ago, but I imagine it was something similar to acetal that he found to work for him.
Below are sellers I found in a quick google search just to give you a general idea of size, price and availability. I have no affiliation with either company, so have a look around for best prices.