Repair by COLOURLOCK

Fill cracks instead of reupholstering with Repair by COLOURLOCK

What is Repair by COLOURLOCK? The repair line from the leather specialist behind the Lederzentrum: glue for tears and backing repairs, sandable fillers for holes and missing spots, re-fatting oil and softener for brittle leather. Each step sets up the next, so colour and sealant hold at the end.

Repair by COLOURLOCK is the repair line from the leather specialist that has supplied upholsterers and refinishers as the Lederzentrum since 1995 and has belonged to Koch-Chemie since late 2023. The products aren't one-off fixes but stations in a fixed sequence: degrease, glue, fill, sand, dye, seal. Re-fatting oil and softener make brittle leather flexible again first, fillers close cracks and missing spots, and glue carries the area from behind.

• The repair stays as flexible as the leather. The fillers are based on polyurethane dispersions: polymer chains float in water, and as it dries they move together and lock into the open collagen fibres of the leather. You notice it when the filled spot flexes as you get in, instead of tearing open again at the first edge.
• Every layer dries on its own. Because the water content evaporates, every fill shrinks as it dries. A thick blob pressed in only skins over on top, stays soft inside, sinks and cracks. That's why the system works in wafer-thin layers with drying in between — more passes, but a repair that stays flat.
• Prep and colour come from the same line. Degreaser, primer, filler, colour and top coat are matched to each other — absorbency, drying time and degree of cross-linking fit together. For you that means you're not hunting for combinations that get along, you just follow a sequence.

Detailing1's tip from the shop: Cleaning isn't degreasing, and that's exactly where most DIY repairs fall down. A surfactant cleaner gets dirt out of the grain, but it doesn't shift skin oil or the silicones from cheap dashboard sprays. Both stay behind as a wafer-thin, water-repellent film — and water-based fillers and colours bead up on it instead of bonding. We regularly get questions about steering wheels whose fresh tint rubs off again after two or three weeks; almost every time the degreasing step was too short. The test takes seconds: after degreasing, the surface has to look dull and feel ever so slightly tacky under your finger. If it's still shiny, go in a second time with COLOURLOCK "Degreaser" and work it on the steering wheel rim and the entry bolster five minutes too long rather than one minute too short.

At COLOURLOCK, repair is the origin and care the spin-off

COLOURLOCK isn't a care brand that does a bit of repair on the side. The line came about the other way round: from 1995 the Lederzentrum supplied upholsterers and refinishers whose daily work is cracked side bolsters, worn-through steering wheel rims and hardened classic-car seats. The care products came later — as prevention against exactly the damage that had been landing on the bench.

That still shapes the formulas today. A repair product isn't judged on how good it looks on day one, but on whether it still holds after a thousand times getting in and out. So every product in this line faces the same question first: does it stay elastic, and does it bond permanently to a material that stretches and contracts with every movement?

Since October 2023 the leather specialist has belonged to Koch-Chemie, and development and production came together in Unna over the course of 2024. You mostly see it in the packaging, now in familiar Koch-Chemie design; that's why the products are listed in the shop under the vendor Koch-Chemie × COLOURLOCK. The system logic behind it hasn't changed.

For you as a user, that's the real difference from an off-the-shelf repair kit. You're not buying an all-purpose paste that's supposed to do everything at once, but individual steps that pros work through in exactly this order. More effort reading, less effort fixing afterwards.

Prep, glue, fill. Three groups in a fixed order

The repair line breaks down into three groups, and their order isn't a suggestion, it's physics. It starts with Pre-treatment & touch-up by COLOURLOCK: COLOURLOCK "Licker Oil" re-fats dried-out fibres so they don't tear further while you work, and COLOURLOCK "Scratch Away" takes out light scratches and pale scuffs purely mechanically, as long as the colour coat is still intact.

For hard, brittle old leather, the Leather softener by COLOURLOCK COLOURLOCK "Old Leather Softener" goes deeper than the re-fatting oil. It works slowly: on badly dried-out classic-car seats it soaks in over hours, and it often takes several passes about 24 hours apart before the leather bends again without cracking. Only then can it take a repair at all.

Gaping tears come next. The products under Leather glue & seam repair by COLOURLOCK are water-based polymer dispersions: they dry clear, stay permanently flexible and don't smell. COLOURLOCK "Leather Glue" (Solvent Free) is the glue for surfaces and backing repairs, COLOURLOCK "Rep Glue" the thinner one for pinpoint fixes and small patches.

Only once the area can carry load again do the Fillers & filler paste by COLOURLOCK come into play. They close whatever is still left as a dip after gluing and give you the flat, sandable surface that colour later covers evenly.

Two products belong here functionally but sit in neighbouring categories in the shop. COLOURLOCK "Degreaser" from Degreaser by COLOURLOCK is step zero before everything else. And you'll find COLOURLOCK "Binder" (Neutral) under Leather dyes by COLOURLOCK, because it's pigment-free and forms the bridge to building up colour.

Filler doesn't replace a backing repair

The most common mistake with tears is filling them from the top. A tear on the seat base or entry bolster is under tension — glued edge to edge or just filled, it rips open again in the same spot next time you get in. Tears like that need support from behind: slide a cut-to-size backing fabric through the tear under the leather, smooth it flat, then apply the glue very thinly with a fine brush between fabric and the back of the leather.

Very thin means exactly that. We keep seeing repairs where the glue went on generously and then migrated through the pores to the surface — especially on thin nappa and clothing leather. There it cures into a dark spot that can't be removed. Less glue and a second pass are always the faster route here.

With fillers, the base colour of the leather decides. COLOURLOCK "Filler" (Black) stops pale repair spots glowing out of dark leather; COLOURLOCK "Filler" (White) does the same the other way round and keeps a dark base from showing through. Both air-dry, can be finely sanded once cured and stay elastic enough to move with the seat. Both need colouring afterwards, because filling power and colour are two separate jobs.

For anything beyond a dip there's Filler paste by COLOURLOCK: COLOURLOCK "Leather & Plastic Paste" cures under hot air, barely shrinks and holds its shape. It rebuilds edges, holes and missing material, even on plastic parts like door cards and the centre console. As a fine filler for a hairline crack it's overkill.

And then there's the case where nothing needs filling at all: COLOURLOCK "Binder" (Neutral) contains no coarse filler particles; instead it soaks into leather that's gone brittle over a large area and firms up the loose pigment layer before colour goes on top. Binder soaks, filler fills, paste builds up. Mix those three up and you'll be doing the job twice.

Thin layers last longer than one thick one

The routine is always the same, and it doesn't forgive shortcuts. Clean, degrease, key the surface with a fine sanding pad, prime, glue or fill, sand between coats, match the texture, dye, seal. Keying looks like a side issue but does three things at once: it trims fibres standing up along the tear edges, opens the pores and increases the area primer and filler can grip onto.

When filling, shrinkage decides the result. Apply so little that the layer can genuinely dry through, and rather add one more pass. Between layers, warm air on a moderate setting helps, then let it cool briefly. What we see day-to-day: the first time, plan on a whole afternoon for one side bolster rather than an hour — not because of the work, but because of the waiting.

Once dry, a filled spot looks smooth, and that's exactly the problem: it reflects differently from the grain around it and looks like a plastic patch. So the dried filler gets softened, smoothed and re-textured before any colour goes on. Skip that step and you'll see the repair every time the light hits it at an angle.

The last common mistake is the easiest one: dabbing colour straight onto a crack you can feel. Leather colour has no filling power. It lays a thin film over the edge, even accentuates it, and is the first thing to flake off at the break. If you can feel it with your fingernail, it needs filling — if you can only see it, it needs colour. What comes next is under Dyeing & finishing by COLOURLOCK.

Not every leather defect belongs in your hands

Two zones are off-limits for DIY repair, and one of them is about more than looks. The outer bolsters of many car seats hide the tear seams for the side airbags. If they get glued, stitched or blocked with filler, deployment can change in a crash. Work on those seams belongs only with certified specialists — no matter how well you handle the rest.

The second no-go zone is perforated leather in climate-controlled seats. Liquid and filler paste run into the hole matrix, make the unprotected edges inside the holes swell and soak into the foam beneath. We deliberately tried it on a test area of a perforated seat cushion: the holes clogged, and in the end the blocked pores stood out more than the scratch we'd started with. Open-pored aniline leather is the third case — it soaks up colour and grease like a sponge and needs airbrush technique instead of a brush.

There's a structural limit too. If the entry bolster hasn't just torn in the leather but the backing fabric has gone and the foam underneath is broken, no filler paste will take the point load of sliding over it. That section is a job for an upholsterer. An honest expectation belongs here as well: heavily filled spots will always feel a bit more even and rubbery than natural leather, and re-dyed zones on a car driven every day will want a refresh after about one to two years.

Where the colour coat still holds and only the surface has suffered, the effort is much smaller. For pale rub marks on the steering wheel rim and light scratches under Leather scratch remover by COLOURLOCK, COLOURLOCK "Scratch Away" on its own is often enough, with no filler or colour at all. And if it's your first repair, a matched package from Repair kits by COLOURLOCK makes for a calmer ride than components picked out one by one.

Your damage decides where you start

Run your fingernail over the spot. If you feel nothing and only see a paler, matte rub mark, the colour coat is intact and COLOURLOCK "Scratch Away" is all it takes. If you feel an edge but the leather is still closed, the work starts with degreasing and ends with filler. If the tear gapes open, glue with a backing repair comes first.

If the leather cracks when you bend it or feels like parchment, flip the order and start further back: re-fat first with COLOURLOCK "Licker Oil", and with very old leather work it soft over several days with COLOURLOCK "Old Leather Softener". Brittle leather you fill straight away simply tears again right next to the repair. We get that follow-up question more often than any other about the repair line.

If material is missing — broken-out edges, holes, exposed foam — the route goes via COLOURLOCK "Leather & Plastic Paste" rather than a filler. And if the surface is brittle over a large area without one dominant crack, stabilise it first with COLOURLOCK "Binder" (Neutral). You'll find all the brand's other products one level up: COLOURLOCK × Koch-Chemie.

The step almost everyone does the wrong way round comes right at the end. After dyeing there's a fresh, still-soft pigment layer on the leather, and instinct says: condition first, then seal. The reverse is right. Sealant first as rub protection, let it cure for at least 24 hours, then condition. Reach for the conditioning milk first and you're working fat under an unprotected colour coat. In a few weeks, what took a whole afternoon has rubbed off again.