Pale natural vegetable-tanned leather parts on a workbench with nitrile gloves, contact cement and a crepe eraser for keeping glue and hand oil off the leather.
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Keeping Hand Oil and Glue Off Light Vegetable-Tanned Leather

ByPeter Joeseph 'Briefcase Maker' Kalafatis

Natural veg-tan keeps every hand that touched it and every drop that missed.

Light vegetable-tanned leather, the pale natural kind that comes undyed from the tannery, is the most honest material on the bench and the least forgiving. It drinks. Oil from your fingers, a smear of contact cement, a wet thumbprint, a strip of tape pulled too fast, all of it goes in and most of it stays, and on a pale hide it shows from across the room. What follows is one job, a small piece in natural veg-tan taken from the box to a finished, glued and stitched object, walked through in order, with the thing that goes wrong at each step.

Video: Unpacking natural vegetable tanned leather bends, from Marcellino NY Briefcase Maker on YouTube.

That video is me taking a shipment of natural vegetable-tanned bends out of the box, which is the moment this whole problem starts. I go over every hide when it comes in, checking for defects. On pale leather, a lot of the defects you find later weren’t in the hide at all. They were put there by whoever handled it.

Out of the box and onto the bench

The first marks go on before the first cut.

Gloved hands holding a natural vegetable-tanned leather panel by its edges to avoid leaving hand oil on the grain.

The step everybody skips is the one where the leather comes out of the wrapping and gets laid flat. Hands go all over it. They smooth it, flip it, drag it to the edge of the bench to look at the grain in better light.

The National Park Service wrote the plain version of the problem in its Conserve O Gram on how to select gloves, meant for museum collections staff. Skin is “covered with residue including oils, dirt, salts, and moisture,” it says, and that residue can stain the things it touches. The same bulletin says nitrile gloves are now preferred over cotton. Cotton is permeable, so it can wick the sweat and oil off your hand and lay them right back down on the object. In its chart, leather turns up only under nitrile.

There’s a catch, and the bulletin admits it: nitrile may not fit tightly enough for fine, detailed work. On a leather bench, that’s most of it.

So do the cheap thing first. Wash your hands, dry them hard, and wash them again after lunch. Handle the hide by the edges and the flesh side when you can. Put a glove on for the long handling, the unrolling, the flipping, the carrying, and take it off when the knife comes out.

The sun is working on it too. Walnut Studiolo’s leather care recommendations say undyed natural veg-tan will tan or darken in sunlight. A panel left half in the light from a window and half in shadow can come back two colors, with a line between them where the frame threw its edge.

Covering what you aren’t working on

Tape saves the grain right up until you pull it.

Once the parts are cut, most of each piece is just lying there waiting. That’s when it picks up the forearm, the elbow, the oily rag, the cup of coffee set down for a second on the corner.

Covering it seems obvious. It isn’t simple. In a leatherworker.net thread on masking tape, the member Mongo says blue painter’s tape left on a lined gun belt for about a week took a little leather off the lining when it came up. CitizenKate, in the same thread, uses a purple low-tack painter’s tape for airbrush masking with no grain damage, and says that blue tape has to come off very, very slowly. Xothique takes the edge off low-tack frisket by pressing it onto fabric before it touches leather. The member Bree’s warning is the one to keep: “you have to be VERY careful.”

The method, as those makers give it, comes down to this. Pick the lowest-tack tape you can find. Test it on scrap from the same hide. Take it off soon, and peel it back slowly and low.

My opinion: on pale leather, a clean sheet of paper laid over the parts does most of what tape does, and it can’t lift anything when you take it away.

Gluing without getting glue on the grain

Put it where the bond is, and nowhere a finger can carry it.

Water droplets beading on a hidden glue spot on natural vegetable-tanned leather while soaking in elsewhere.

Glue is the step that ruins the most pale leather, because it’s wet, it’s sticky and it goes on with the same hands that are about to pick up the next piece. I fuse two pieces of leather together for a lining, and on my channel there’s a video of me gluing a chestnut bridle lining, “Gluing my Chestnut Bridle Leather Briefcase Lining”. On dark bridle a stray streak hides. On natural veg-tan it’s a stain with an outline.

Sailrite’s guide to gluing leather before sewing gives the rules in order. Spread a thin coat on both pieces with a spatula, a brush or a roller. Rough up any finished surface first so the glue grips. Wait until water-based glue goes clear, or solvent glue goes tacky, before the pieces meet. Put glue “only where you want to bond the leather together.” And keep the surface clean, it says, because excess glue can mar the leather’s grain.

That last line is the whole post in one sentence from a supplier.

What goes wrong is rarely the glue line itself. It’s the spatula set down on the panel. It’s the finger that pressed a seam and then steadied the next piece by its face. It’s a thread of cement stretched across the grain when two coated parts were lifted apart. Keep a rag for your fingers that never touches the leather. Set the spreader on its own scrap.

When glue lands on the grain anyway

Dry glue hides. Water will find it for you.

Sailrite’s fix for glue on the grain is to rub it off with a natural rubber eraser, and to break up dried glue elsewhere with a folder. The crepe eraser is the tool most leatherworkers name. In a thread on cleaning up excess contact cement, the member Elton Joorisity says a piece of crepe shoe sole works wonders. celticleather rolls a dried spoonful of cement into a ball and rubs with that. katsass Mike gets around the problem by using very little cement, in only a few places, and stitching the rest.

The trouble is the glue you can’t see. In a thread called rubber cement blunder, the poster Hilly couldn’t see or feel any cement left after cleaning up. The member TwinOaks suggested a light mist of water as a test, because “It will bead on the glue.” She misted it, and there was a spot the water wouldn’t go into. She wiped that spot with alcohol on a cotton ball, let it dry, misted it again, and that time it took the water.

That test matters on natural veg-tan because glue under the surface is a resist. Dye won’t go in. Oil won’t go in. Neither will the slow darkening the rest of the panel does on its own, so years later there’s a pale ghost of a fingertip on a piece that’s otherwise gone the color of toast.

The member DavidII said in the same thread that the eraser takes dried cement off the surface, and that he didn’t know what to do if it had soaked into the fibers. Nobody there had a sure answer. In the excess cement thread, Dwight’s answer for the worst cases was to slice the cemented layer off with a sharp blade and then dye and finish the piece. That’s surgery. You’d only do it on a part that was about to be thrown out anyway.

Cleaning up before the finish, and when to stop

Some cures leave a bigger mark than the one they were sent after.

A new natural vegetable-tanned leather piece beside an older one that has darkened evenly with handling.

The urge, once a spot shows up, is to scrub it. In a thread on cleaning veg-tan, the poster dwakefield00 tried acetone on an oil spot before dyeing and said it seemed to discolor a larger area, while the oil spot stayed. The member Bob Blea said denatured alcohol is a powerful cleaner but will dry out the leather. My Leather Care page says the same thing about cleaners in general. They take dirt out, and “They also take out oil and make it dry,” so conditioner has to follow.

Oxalic acid is the old trick. In a thread of questions about oxalic acid, the member Randy Cornelius says, “Think of it as a cleaner, not a bleach,” and wipes the whole piece with a weak solution, then rinses it with clean water. Spinner’s test panel came out even in color where the untreated half stayed splotchy, and he says to wear gloves when you put it on. The forum doesn’t cover safety beyond that, so read the product’s safety sheet before you open the jar. For a spot that won’t come out, the cleaning thread’s quieter answer was to give the whole piece one light, even coat of oil so the spot stops standing alone.

Now the turn. I’ve spent this whole post telling you to keep hand oil off natural leather, and I build in a leather that’s supposed to take it. Walnut Studiolo says the oils from your hands condition veg-tan and darken it with use, and that pieces handled every day may barely need conditioner. In my experience, sun and oil are what speed up the patina on undyed vegetable-tanned leather. Part of why I like American veg-tan bridle is that its patina runs deeper, and it takes fingerprints less visibly than the waxy English kind. So the hand oil I’m warning you about on day one is the color people pay for in year five.

The difference is evenness. A whole case going dark from being carried is a record of use, which is the argument of Ten Million Dollars for a Scratched Handbag. One thumbprint, one glue ghost, one stripe of sun on a piece nobody has carried yet is just a mistake that’s going to age along with everything else.

And when the marks win, there’s always the other road. You can take a natural piece dark on purpose, all of it at once, the way the post on hand-dyeing natural vegetable-tanned leather black does. That isn’t hiding the mistake. It’s deciding it was never going to be a pale piece.

For care once a piece is done and in use, the conservator-style method in How to Clean Leather the Way Conservators Do picks up where this one stops.

Barge All Purpose Cement, Quart: A quart of solvent-based contact cement. See it on Amazon (affiliate link).

DEEDYGO Genuine Bone Folder: A genuine bone folder for creasing and burnishing. 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).

Pure Neatsfoot Oil, 8 oz: An 8 oz bottle of pure neatsfoot oil for leather. See it on Amazon (affiliate link).

Leather Conditioner with Grass-Fed Beef Tallow and Lanolin: A leather conditioner made with grass-fed beef tallow and lanolin. See it on Amazon (affiliate link).

Skidmore’s Leather Cream: A leather conditioner cream, one option for the conditioner step. See it on Amazon (affiliate link).

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Sources

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