Dyeing & finishing by COLOURLOCK

Re-dye leather instead of reupholstering it with the COLOURLOCK dyeing system

What is dyeing & finishing by COLOURLOCK? The leather specialist's professional line for a complete colour build-up: primer and barrier coat, opaque leather dye and stabilising filler colour, colour-neutral refreshers for smooth leather and nubuck, top coat from satin-matt to high gloss, and additives that let you set gloss level, feel and abrasion resistance.

Dyeing & finishing by COLOURLOCK is the line detailers and upholsterers use to dye leather instead of re-covering it. It isn't a range of stand-alone products but a process by the data sheet: degrease, prime, fill, dye, seal with top coat, fine-tune the finish with additives. The line has been developed since 1995 at Lederzentrum, and today the leather specialist is part of Koch-Chemie in Unna.

• Colour is built up, not painted on. Dyes and top coats are water-based polyurethane dispersions: polymer particles float in water, and as it evaporates they move together and fuse into a continuous, elastic film. A film like that handles stretch in the triple-digit percentage range — enough for a seat base to compress as you climb in. Provided it's laid down in many wafer-thin layers rather than one thick one.
• The bases are colourless, the shade comes on top. COLOURLOCK "Leather Fresh", COLOURLOCK "Nubuck Fresh" (Neutral) and COLOURLOCK "Binder" (Neutral) carry no pigments. They provide build, feel and gloss level, while the car's shade comes from the original leather colours mixed to sample. What that means for you: you decide on build and finish first, and only then on colour.
• You set gloss, feel and hardness yourself. Matting agents, feel additives, thickener and crosslinker all act on the same mix. One to two percent crosslinker in the top coat decides whether the surface can handle wet abrasion, a feel additive whether the seat feels velvety or waxy. How you notice: in the end, the repair doesn't stand out, either to the eye or to the touch.

Detailing1's tip from the shop: It's not the shade that gives a dye job away, it's the gloss level. We regularly get questions about re-dyed side bolsters that look greasy-shiny under raking light while the rest of the seat stays satin-matt — the colour is right, the way it reflects light isn't. That's why every surface starts with a test patch: do a palm-sized sample on the underside of the seat or behind the backrest, let it dry completely and hold it next to the original in daylight. Wet, every shade looks darker and glossier than dry, so judging after five minutes will reliably lead you astray. If the gloss is off, don't fix it with more colour, adjust the mixing ratio in the top coat or use the matting additive COLOURLOCK "Duller".

With COLOURLOCK, dyeing is a trade job, not an off-the-shelf fix

Leather dye comes in two worlds. One is tinting kits for end users: dabbed on, superficial, without much build-up, but hard to get wrong. The other is coating chemistry that works with spray gun, drying breaks and mixing ratios. This line belongs to the second world.

The reason is where it comes from. From 1995, Lederzentrum supplied upholsterers and detailers whose daily work is worn steering wheel rims, faded dashboard covers and seat bolsters where the colour coat has rubbed through. So what was developed wasn't one product that does everything, but a chain of steps that pros work through in a fixed order. Since October 2023 the leather specialist has been part of Koch-Chemie, which is why the line appears in the shop under the vendor Koch-Chemie × COLOURLOCK.

The chemistry behind it has become quieter over the years. Solvent-based paint systems have largely disappeared, and today dyes and top coats are water-based, built on polyurethane and acrylate dispersions. What that means for you: no solvent smell in the cabin, but drying behaviour that depends on temperature and humidity. Water evaporates more slowly than solvent, and that's exactly where the patience this process demands comes from.

What this line has over a repair kit isn't the colour, it's access to every single parameter. Coverage, gloss level, feel, viscosity and degree of crosslinking can all be set separately. That's more decision-making than a ready-made product asks of you, and less rework when the result has to hold up next to an original surface.

Each group in the line does exactly one job

First up is primer & adhesion promoter: it makes sure the colour bonds at all. COLOURLOCK "Leather Primer" soaks into the sanded, degreased smooth leather and forms the bridge between leather grain and colour film. COLOURLOCK "Blocker" is the special case for old leather: a barrier against anything pushing up from below — migrated plasticisers, old grease deposits, bleeding denim dyes. And COLOURLOCK "Plastic Primer ND" does the same job on plastic parts whose surface is naturally too smooth for water-based colour.

The leather dyes are the group that actually replaces colour rather than refreshing it. COLOURLOCK "Leather Colour" covers surface-coloured smooth leather with pigment and is the product for true colour changes and for areas where the factory colour has worn through. COLOURLOCK "Binder" (Neutral) works alongside it without pigment: it creeps into leather that has become brittle across a large area, bonds loose fibres from within and creates the solid base on which colour later covers evenly.

The colour refreshers come in one step earlier, where the colour coat still holds and just looks tired. COLOURLOCK "Leather Fresh" comes as a colour-neutral base in several gloss levels, from the dull version for a matt factory look to the glossy one for leather that should visibly carry more shine. For nubuck, suede and open-pore rough leather, Nubuck Fresh is its own base, because a film-forming colour would destroy the velvety surface.

The Top Coat & finish is the layer that protects the work at the end. It sits as a clear, elastic film over the colour, takes the abrasion and at the same time sets the gloss level — from a matt finish that scatters light diffusely, through a light sheen, up to a high-gloss finish for a patent-leather look. COLOURLOCK "Top Life" is the surface protection for when the freshly dyed area needs extra protection against friction.

The additives & aids are the adjustment dials. COLOURLOCK "Duller" lowers gloss steplessly, COLOURLOCK "Soft Slip" makes the surface velvety, COLOURLOCK "Wax Slip" waxy and grippy, COLOURLOCK "Thickener" thickens so nothing runs on vertical seat bolsters, and COLOURLOCK "Crosslinker CD", as a crosslinker, increases resistance to wet abrasion. COLOURLOCK "Stitch Covering Gel" belongs here functionally, although it doesn't adjust anything: it masks light contrast stitching so it doesn't get coloured when you spray.

Refreshing, dyeing and stabilising are three different jobs

The most common question we get about this line boils down to: is refreshing enough, or do I need to dye? The answer lies in the state of the colour coat, not the age of the car. If it's intact and just looks dull, unevenly glossy or tired in colour, COLOURLOCK "Leather Fresh" is the right amount of effort. If it's rubbed through and the leather underneath shows light, only pigment will help.

That's where COLOURLOCK "Leather Colour" takes over. The difference isn't one of degree: the refresher evens out an existing look, the leather dye builds a new covering layer. The application differs accordingly — refreshers can be worked over the surface with sponge and cloth, while a true colour change is sprayed, because only the fine mist delivers the thin, even layer that stays elastic.

The third job is the least visible. COLOURLOCK "Binder" (Neutral) changes neither colour nor gloss, it consolidates. On leather that's gone brittle over a large area and shows fine crackle patterns when pressed, it's the step without which any colour on top gets torn along with it. Binder soaks in, Leather Fresh evens out, Leather Colour covers — mix these three up and you'll be doing the job twice.

One limit runs across all three: damage you can feel doesn't belong in this category. Anything your fingernail catches as an edge has to be closed first. Cracks, holes and broken edges are handled by repair with adhesive, filler and compound. Colour has no filling power; laid over an open edge it actually accentuates it and is the first thing to flake off there again.

Step zero is the degreaser, not the colour

No step decides durability as much as the one almost everyone cuts short. Skin oils, sweat and silicones from cockpit sprays sit on the leather as a wafer-thin release film, and water-based primers and dyes won't stick to it. That's why cleaning comes first, followed by a degreaser worked in until a white cotton cloth picks up a slight tint of the leather colour. That colour transfer is the signal that the old finish is open.

After that, the process runs without shortcuts: mask contrast stitching, scuff the surface with a fine sanding pad, prime, fill and sand between coats, dye, seal. Scuffing seems like a side issue, but it increases the surface that primer and colour grip onto and breaks up the oxidised remnants of the old top coat. The primer itself is deliberately kept thin and only dried to a slightly tacky state — a thick primer coat stays soft and later lets the colour on top shift.

For colour application there's one rule: many mist coats instead of a few wet ones. Force-dry briefly with warm air between passes, then the next layer. From everyday life at Detailing1: for two front seats, count on a full day rather than three hours, and most of that is waiting. A layer applied too thick cures as a rigid block, feels like plastic and cracks at the first fold.

The finish is the top coat, and that's where the gloss decision happens. Matt and gloss are mixed in ratio until the gloss level matches the surroundings, and one to two percent crosslinker goes in fresh. After that, only time counts: thermally the surface is dry after minutes, but chemically fully crosslinked only after 24 to 48 hours. Sit on the seat or apply leather lotion before that and you're working grease into a layer that isn't finished yet.

Where dyeing stops and the upholsterer takes over

One zone is off-limits, and it's not about looks. The outer bolsters of many seat backrests contain the side airbag tear seam. It's designed as a predetermined breaking point and subject to documentation requirements; if it's painted over, sealed with filler or stiffened by hard, crosslinked colour layers, deployment behaviour shifts in the millisecond range. Work on this seam belongs with a specialist upholstery business holding the relevant certification, however well you handle the rest.

The second limit is perforated leather in ventilated seats. Colour and filler run into the hole pattern and clog it, and that doesn't just ruin the look, it kills the seat ventilation. Pros spray dry there in a cross pattern from further away with less material flow, and clear clogged holes before curing. We recreated on a perforated sample piece how quickly this tips over: after the third layer the holes at the edge of the area were closed, and the blocked holes ended up far more noticeable than the light wear it was originally about.

Open-pore aniline leather is the third case. Technically it can be over-dyed with pigment, but in practice it loses exactly what it was bought for: its soft, breathable feel. You have to be just as honest about heavily hardened, shrunken leather — if the material crackles when bent and feels like cardboard, the fibre structure is gone. No colour brings it back. And where seams have torn or the backing fabric is worn through, no coating holds the cover tension; that's upholsterer's work.

Finally, the limit that gets argued about most: the shade. A shade mixed exactly to the factory recipe won't match ten-year-old leather anymore, because UV light and heat have shifted the original. Then there's metamerism — two colours that look identical in daylight can drift apart under artificial light. That's why in practice you dye through to the next seam instead of spot-repairing: the seam is the visual break line beyond which a slight shade difference no longer shows.

The state of your leather decides where you start

Run your fingernail over the spot and look at what's left. If the colour coat is still intact and just looks dull or uneven, a refresher from the Leather Fresh family in the right gloss level is enough, plus matting additive if the factory look is more matt than the result. If light substrate shows through, the job starts with primer and COLOURLOCK "Leather Colour". If the surface is brittle over a large area, COLOURLOCK "Binder" (Neutral) comes first. For nubuck and suede, the only route is COLOURLOCK "Nubuck Fresh" (Neutral).

The shade comes after that, and there's a shortcut via the car: the original leather colours are mixed to sample and sorted by car brand, from Audi and BMW through Mercedes-Benz and Porsche to Volvo and Land Rover. So you don't choose from a colour chart, you go by your model — and with aged leather, add a test patch before the whole seat gets done. If you need the complete build-up in one go, you'll find it matched in the complete dye kits. All other products from the brand are one level up: COLOURLOCK × Koch-Chemie.

Realistic expectations are part of it. A properly built dye job lasts around three to five years on steering wheel and entry bolster, roughly 50,000 to 80,000 kilometres in everyday use, before the first shiny spots appear on the top coat. On surfaces with little wear, much longer. After that you don't re-dye, you renew the wear layer — that's the difference between a system and a coat of paint.

And the point where most dye jobs fail isn't the colour. It's the top coat people leave out because the surface already looks good after dyeing. Plain leather dye has no real abrasion resistance; without the clear protective layer on top, the fresh pigment coat rubs off again on jeans seams and belt buckles within a few months. Skimp on the top coat and you're skimping on the only step that keeps the colour in place.