Vegetable-tanned leather briefcase flap on a workbench with a half-burnished edge, a wooden slicker and burnishing supplies for hand burnishing leather edges.
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Hand Burnishing Edges on Vegetable-Tanned Leather

ByPeter Joeseph 'Briefcase Maker' Kalafatis

Sand it flat, wet it, rub it until it closes.

A cut edge of vegetable-tanned leather is a raw wall of loose fibers. Hand burnishing is the slow work of pressing those fibers back down, with water, friction and a little heat, until the edge goes hard and glassy and quits shedding on your sleeve. I hand burnish vegetable-tanned leather edges, and the video on my channel shows that work.

Video: How To Hand Burnish Vegetable Tanned Leather Edges, from Marcellino NY Briefcase Maker on YouTube.

Nothing about it is clever. I do it by hand because that’s the traditional way, and on bridle the traditional way still earns its keep. The suppliers who write it up, from Sailrite to Tandy to Weaver, give much the same order of work, and each one gets named where its step shows up. Pass by pass, the only question is what the fibers are doing right now.

Friction is the tool

The slicker is just the handle on the heat.

Hands hand burnishing a damp vegetable-tanned leather edge with a grooved wooden slicker.

Sailrite’s guide to slicking leather edges lays out the core of it. Friction makes heat, heat packs the fibers together, and the packed edge is sealed. Tandy’s article on beveling, burnishing and polishing comes at it from the other side: friction compresses and smooths the fibers into a glossy finish.

Pick up an old wooden hammer handle off any working bench and you’ll see the same thing. The grip has gone dark and slick exactly where a palm rode it, year after year, and nobody varnished it. Sweat, pressure and rubbing packed that wood shut. A burnished edge is made the same way, only in minutes, and along a line no wider than a pencil.

That tells you where the finish lives. It isn’t a coat. It’s the leather itself, packed tight. Sailrite adds that the sealed edge holds the leather’s own oils and moisture in, sheds water better, and helps protect the stitching thread from rotting. On a briefcase that thread runs close beside the edge for its whole length, so the edge is guarding more than itself.

This is also why vegetable-tanned leather is the leather that burnishes. Sailrite says veg-tan “works best.” My opinion: bridle suits it well. My Leather Choices page describes English bridle as veg-tanned and traditionally very waxy, so the edge already carries some of what an aid would add.

First pass: sanding the cut flat

Fibers that stick up cannot be pressed down evenly.

In my view, burnishing magnifies whatever is underneath it. A dip in the edge shows as a dull shadow in the shine, and a step between two glued layers shows as a line you can catch with a fingernail. So the first pass is mechanical. Shape, not gloss.

Sailrite’s first step is to sand the edge flat and flush and clear out excess glue. The Leather Craft Toolbox guide to edge burnishing recommends fine sandpaper to take off frayed fibers and to bring overlapping layers into line. Weaver’s page on burnishing leather adds a tip that’s easy to skip: a higher grit before burnishing gives a glossier edge.

None of these sources sets a universal grit sequence, and I’m not going to make one up. The Maze Leather writer Emily Medlock, in her burnishing leather edges guide, suggests medium grit and shows 120. For a repair, the earlier post on this site about patina says frayed edges should be bevelled back to sound leather and lightly sanded to 320 to 400. Those two numbers frame the range. A coarse grit shapes. A fine one prepares.

Glued layers are where this pass earns its pay. When I fuse two pieces of leather for a lining, the edge goes sand, bevel, burnish, in that order, and the glue line is the spot that fights back.

Beveling belongs here too, before any water goes on. Tandy lists skipping the bevel as a common mistake, since a sharp corner is harder to rub round.

Second pass: moisture in the fibers

Damp, not wet. The edge should drink it, not drip it.

Macro comparison of a sanded raw vegetable-tanned leather edge and a smooth glossy burnished edge.

Sailrite names a dry edge as the usual cause of a poor burnish. Leather Craft Toolbox dampens the edge with a sponge before sanding and burnishing, and Medlock tells the reader to re-lubricate whenever the edge starts to dry. Damp is the condition to hold, and holding it is most of the job.

Then comes the choice of aid. On the short list, the sources agree.

  • Water. Weaver says it works well for slicking. Medlock notes that it needs frequent reapplication, and warns that a drop in the wrong place can ruin a piece.
  • Gum tragacanth. Fiebing’s product page for gum tragacanth says it is used to “slick leather edges in preparation of edge finishes.” Its directions: spread a small amount evenly along the edge with a dauber or paddle, rub with a slicker or bone folder, moderately firm, until smooth and glossy, repeat for more shine, and let it dry. Medlock calls it her favorite.
  • Beeswax. Weaver says it works nicely. Leather Craft Toolbox uses it to help the slicker along.
  • Saddle soap and newer gums. Weaver lists both, and Sailrite includes saddle soap among its lubricants.

Too much of any of these is its own failure. Tandy warns that over-wetting can weaken the fibers and stop the edge from sealing. Weaver goes further: too much edge finish leaves edges mushy, and the leather needs to keep some body.

Keep the aid on the edge. Weaver lists gum, oil, wax or water on the face of the leather as a problem for top coating later, which is a polite way of saying you’ve made a stain you’ll be looking at for years.

My opinion: on stiff, waxy bridle, the hardest part of this pass is keeping your hand still. I’d rather lay on a second light coat than flood the edge once.

Third pass: rubbing the edge closed

Short strokes, fast, and stop at the shine.

This is the pass in the video. A slicker, a groove that fits the thickness, and speed from the forearm.

Weaver’s method is specific. Pick the slicker groove that matches the leather’s thickness, run it back and forth along the edge for a couple of seconds, then move to the next larger groove to polish. Tandy says to start with light pressure and add more as the edge begins to shine, and lists canvas wrapped around the edge as a hand alternative that builds heat.

Leather Craft Toolbox gives the most useful working limit of any of these guides: rub no more than about 25 cm at a time, because a longer stroke spreads the friction too thin to build heat. Work a section, move on, come back.

Then do it again. Sailrite’s steps loop: lubricate, burnish, check, lubricate again. Fiebing’s directions loop the same way. The edge darkens slightly as it closes, and Sailrite’s edge-finishing guide lists that as a normal effect of burnishing. A finished edge should feel smooth under a fingernail, look round, and stop shedding fibers.

There’s a powered version of all this. My YouTube channel has a video of burnishing briefcase flap edges with a Weaver wood roller. Weaver sells a wooden roller for its Master Tool Power Edge Burnisher, and the page for the Master Tool Power Edge Burnisher says that roller is used for final burnishing to a high gloss. The physics doesn’t change with a motor. The motor only spares the arm.

My opinion: by hand, there’s a point where the edge goes from satin to glass, and that’s the point to stop. Past it, you’re just warming the leather and wearing out your shoulder.

Glass isn’t always the goal. On some vegetable-tanned pieces I dye the edge, burnish it lightly and leave it there. No paint. Just enough rubbing to close it.

The fair case for painting an edge

Some leathers barely burnish. Paint is not cheating.

Finished bridle leather briefcase with rounded, hand-burnished edges and saddle stitching beside them.

I build briefcases in bridle and I burnish them, so you already know which side I’m on. That’s the reason this section has to be fair, because burnish good, paint bad is the easy post to write, and the sources won’t hold it up.

Sailrite’s guide to finishing leather edges says edge paint is best for thin, supple, pliable leathers that don’t burnish well, naming chrome tan, bonded and exotic leathers, and adds that veg-tan can be painted too. It also gives the difference in one line: paint “sits on top of the edge rather than sinking into the leather fiber.” In a leatherworker.net thread on burnishing versus edge painting, the member Hardrada writes that chrome tan does not burnish well, so it’s edge paint or folded edges, and the member Klara adds that “only fairly stiff, thick leathers can be burnished.” She also points out that paint is the choice when an edge has to match the face colour exactly.

Paint isn’t the lazy option either. Sailrite calls it the most labor-intensive finish, usually three or more coats with sanding in between, and a member of the same thread describes painted edges on crocodile goods as quite time consuming.

So paint has a real job. Whether it’s the right job for the leather on your bench is the only question worth asking.

For thick bridle my answer is already on that Leather Choices page. Hermann Oak bridle comes “very thick, around 8 to 12oz,” and for a heavy, durable briefcase in it I recommend keeping “the edges traditional by burnishing, not painting.” Stiff and thick is what Klara says burnishes. In the same forum thread, Hardrada also notes that paint can rub off a bit.

My opinion: a burnished edge on bridle wears with the case, because it is the case. A painted edge sits on it. The patina post says the burnish line catches light differently from the aged surface beside it, and that it blends over time. Paint, in my view, never quite blends. It wears, and then somebody repaints it.

Here’s the part I’d rather leave out. I paint edges too. On lined and suede-lined cases I use a latex-based edge paint, because it glues the layers together while it covers them, and a burnish can’t do that. My opinion, from my own bench: flat black holds up better than glossy.

So the man preaching burnish keeps a pot of paint on the shelf. Nothing cited here puts a painted bridle edge and a burnished one side by side through years of use. Some of my preference is proof. Some of it is just what I like the look of.

Common mistakes

Most bad edges are dry, wet, rushed or dyed in the wrong order.

The same errors show up across every guide here.

  • Burnishing a dry edge. Sailrite calls it the usual cause of poor results, and Medlock’s fix is to re-lubricate the moment the edge starts drying.
  • Drowning it. Tandy says over-wetting weakens fibers and stops the seal. Weaver warns of mushy edges.
  • Burnishing before dyeing. Medlock explains that the lubricant seals the edge and resists stain, so dye first. Leather Craft Toolbox says dye applied after gum tragacanth will not adhere properly, and Fiebing’s directions put dyeing before the gum. The forum thread agrees that compressed fibers take dye badly.
  • Skipping the bevel or the sanding. Tandy flags the first. Sailrite says glue residue and uneven edges stop the finish from going flush.
  • Long strokes. The 25 cm limit from Leather Craft Toolbox exists because a long stroke never builds heat.
  • Too much speed on a machine. Sailrite warns that a power burnisher run too fast can burn the leather.
  • Aid on the grain. Weaver’s warning about the face of the leather bears repeating, and Medlock adds water dripping onto the rest of the piece to her own list.

Not one of these is about talent. Most of them are a hand moving faster than the leather wants it to, and that’s a hard habit to break when the shine is sitting right there under your thumb.

Ebony Wood Leather Edge Burnisher (slicker): A grooved wooden slicker of the kind the burnishing steps above call for. See it on Amazon (affiliate link).

Fiebing’s Gum Tragacanth, 4 oz: A 4 oz bottle of gum tragacanth, a burnishing aid for leather edges. See it on Amazon (affiliate link).

Fiebing’s Edge Kote, 4 oz: A 4 oz edge coating for finishing leather edges. See it on Amazon (affiliate link).

Wet Dry Sandpaper Assortment, 45 Pieces: A 45-piece wet and dry sandpaper assortment that starts at 400 grit. See it on Amazon (affiliate link).

As an Amazon Associate I earn from qualifying purchases. A commission may be earned if you buy through this link, at no extra cost to you.

Sources

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