WOOD REPAIR FILLER · ART. 337
The wood repair that disappears under the finish.
LEINOS 337 Wood Filler — a water-mixed mineral powder that fills cracks, knots and gaps up to 15 mm deep on interior and exterior wood. Nine wood tones to match the timber, sandable in about 45 minutes, and it takes any LEINOS oil, wax or lacquer over the top. Solvent-free. Made in Germany by Reincke Naturfarben.
Colour Range
Nine Wood Tones
Nine opaque filler tones matched to common timbers — choose the one nearest your wood so the sanded repair reads as grain, not a patch.
420
White
421
Ash
422
Oak
423
Natural Oak
424
Smoked Oak
425
Oak Knot
426
Cherry
427
Beech
428
Black
These are opaque putty tones — the set filler is solid, so pick the closest match to the surrounding wood. A clear oil or wax over the top warms the tone slightly, exactly as it warms the wood. Screen chips approximate the real filler; confirm the match against an offcut before a visible repair.
Matching Your Timber
Not sure which tone matches your wood? Send an offcut or a photo and our Delhi team will advise on the closest 337 shade — and the fill-and-finish combination for an invisible repair.
Mechanism & Use
How LEINOS 337 Wood Filler works.
An ordinary filler shrinks as it dries — pack a deep knot or a 15 mm crack and it crazes, sinks and drops out, or dries a dead grey that will not take a wood finish. 337 is built on natural gypsum and coloured to nine wood tones: it sets hard and crack-free in the void, sands flush, matches the timber, and takes any LEINOS finish over the top.
Natural gypsum sets the repair hard
Calcium sulfate takes up the mix water and recrystallises into an interlocking crystal matrix — the fill hardens by locking its own structure, not by drying-shrinkage. A 15 mm knot or crack sets solid and dimensionally stable in one pass instead of sinking and dropping out.
Nine wood tones, matched to the timber
Mineral pigments colour the powder to nine wood tones — white, ash, oak, natural oak, smoked oak, oak knot, cherry, beech and black — so the sanded-flush repair reads as grain, not a patch.
Takes any LEINOS finish over the top
Once sanded flush it accepts any LEINOS oil, wax or lacquer, so the repair carries the same finish as the wood around it — interior or exterior.
Solvent-free, water-mixed, fast
Mixed three parts powder to one part cold water, workable in about 20 minutes and sandable in about 45. Solvent-free, with no VOC to off-gas. Made in Germany by Reincke Naturfarben.
Where It Lives
Where 337 lives
Knots and knot-holes in new timber
Filling and colour-matching live knots before an oil or lacquer.
Cracks, checks and splits in furniture and joinery
Closing shakes and gaps in tabletops, doors and cabinetry.
Nail holes, screw seats and gouges
Filling fixing holes flush before the finish on trim, skirting and panelling.
Exterior wood repairs
Cracks and gaps in gates, decking boards, cladding and garden furniture.
Restoration and refinishing
Rebuilding damaged edges and gouges on old wood before re-oiling or re-lacquering.
Colour-matched patch repairs
Nine wood tones so the repair vanishes under a clear finish.
Ingredient Disclosure · Origin
Declared in full. Made in Germany.
337 carries no coating-grade DIN/EN test class — it is a mineral repair filler, not a coating. The honest anchors are full-ingredient disclosure, the German trade GISCODE classification, and German manufacture. It is not toy- or food-safe: 337 carries a small in-can preservative, so skin- and food-contact certification does not apply.
Trade Safety Class
GISCODE CP1
German trade occupational-safety code — gypsum/cement-based product, low-chromate class.
Institutional Pledge
InVeNa Member
Reincke Naturfarben — full-ingredient-disclosure pledge for natural building products.
The TDS is downloadable below — the nine colours, the mix ratio, the working and sanding times, and the GISCODE classification. 337 is a mineral repair filler that carries a preservative (benzisothiazolinone) to keep the mixed paste stable, so it is not a toy- or food-safe finish — avoid breathing the dry powder and clean tools with water. The Safety Data Sheet (SDS) is supplied on request from LEINOS India for the full hazard register; where you need a written specification packet for a project, it is available to architects and contractors on request. Use Get Expert Advice above.
Read The Full TDSCoverage
Varies by application — you mix only what a repair needs. Sold by weight (0.1 kg / 0.5 kg / 5 kg), mixed 3 parts powder to 1 part cold water; no fixed spread rate.
Drying Time
Workable for about 20 minutes after mixing; sandable after about 45 minutes. Apply at 5–30 °C.
Tools
Spatula / putty knife, Mixing container, Sandpaper
Step by Step
How to Apply
Prepare the wood. The repair area must be firm, dry, clean and dust-free; rake or rout out any loose or soft fibre from the crack or knot so the filler keys to sound wood.
Mix the powder with cold water. Measure three parts 337 powder to one part cold water (up to 1.5 for a looser mix) and stir to a smooth, lump-free putty. It is ready at once and stays workable for about twenty minutes, so mix only what you will use.
Fill the crack or knot. Press the putty firmly into the defect with a spatula, right to the bottom of the void and slightly proud of the surface; it fills to 15 mm deep in one pass without shrinking back.
Pull it flush. Draw the spatula across to strike the fill level with the surrounding wood, and wipe back any smear before it sets.
Sand smooth. After about forty-five minutes the fill is hard enough to sand; work it flush and feather the edge into the grain until the repair disappears.
Finish over the top. Once sanded, coat the piece as normal with any LEINOS oil, wax or lacquer; the repair takes the finish with the wood around it. Clean tools with water.
Coats & Recoating
- Mixed and used by application, not by coat-count.
- Mix 3 parts powder to 1 part cold water; mix only as much as you can use within about 20 minutes.
- Sandable after about 45 minutes; then finish with any LEINOS oil, wax or lacquer.
Cleaning & Storage
- Clean tools with water immediately after use, while the mix is still wet.
- Store in a dry, cool place, sealed. In the original sealed packaging the powder has an unlimited shelf life.
First time with Wood Filler? Our technical team runs complimentary on-site walkthroughs for contractors — full application protocol, start to finish.
System & Substrates
Fill, sand, then finish — with any LEINOS coating.
337 is a standalone repair filler, not part of a fixed system: fill the defect, sand it flush, then finish the piece with whatever the job calls for — Interior Hardwax Oil 290, Terrace Wood Oil 236 outdoors, or Wax Varnish 600. Supplied as a dry powder in 0.1 kg, 0.5 kg and 5 kg packs; you mix only what a repair needs with cold water (3 : 1), so there is no fixed spread rate. Interior and exterior wood.
Repair, then finish
One filler; the finish is whatever the job specifies.
Topcoat Options
Choose the finish character; the primer underneath stays the same.
Substrate Fit
337 works on — and what it doesn’t.
Suitable
Recommended substrates
- Interior wood — furniture, doors, floors, panelling, joinery
- Exterior wood — decking, gates, cladding, garden furniture
- Knots, knot-holes and dead knots
- Cracks, checks and splits up to 15 mm
- Nail holes, screw seats and gouges
- Softwood and hardwood
Honest Limits
Where to use a different product
- Structural or load-bearing repairs — 337 is a cosmetic repair filler, not a structural adhesive or a wood-rebuild epoxy.
- Gaps deeper than 15 mm in a single pass — build up in layers, or use a backing.
- Permanently wet or submerged wood — a cured gypsum-based filler is not for constant water immersion.
- Mineral walls, plaster and drywall — for interior wall filling use LEINOS 684 Interior Smoothing & Texturing Filler
- Children's toys and food-contact surfaces — 337 carries a preservative and is not certified for skin or food contact.
Use With Care
Working safely with 337
- Contains 1,2-benzisothiazol-3(2H)-one (benzisothiazolinone) — may cause allergic reactions in sensitised individuals.
- Do not inhale the dry powder — mix in a ventilated space and avoid stirring up powder dust; wear a dust mask when sanding the cured filler.
- Keep out of reach of children.
- Avoid release to the environment. Do not wash wet residues to drains, soil or watercourses; let residues set and dispose of the solid with construction waste.
- Dispose of according to official regulations. Disposal code: EAK/EWC 08 01 11. Safety Data Sheet (SDS) is supplied on request from LEINOS India.
Related Work
Interior wood projects from our portfolio
Documented interior wood projects. Captions show which LEINOS finish was used.
Full Declaration
Composition
Every ingredient declared on the label. The Trust Hub explains what each one does and the standards behind it.
Calcium Sulfate · Natural Gypsum
The self-setting mineral binder. Finely ground calcium sulfate takes up the mix water and recrystallises into an interlocking crystal matrix, hardening by locking its own structure rather than by drying-shrinkage — so a deep 15 mm fill sets solid and does not shrink back or drop out of a knot.
Calcium Carbonate · Chalk
The white matt mineral body. Chalk bulks the compound, gives the cured filler its matt surface and clean sanding feel, and fills volume economically alongside the gypsum — the same chalk LEINOS uses across its mineral products.
Mineral Pigments · Nine Wood Tones
Earth and oxide mineral pigments colour the powder to nine wood tones so the sanded repair matches the timber and reads as grain, not a patch. The colour is in the filler itself, not a stain over it.
Benzisothiazolinone · In-Can Preservative
A small preservative keeps the packed powder and the mixed paste stable and mould-free. It is why 337 is declared honestly and is not a toy- or food-safe finish — the trade-off for a ready-to-mix, storable filler that keeps indefinitely.
Got Questions?
Frequently Asked
Quick answers on formulation, application and Indian-climate suitability. Pulled from our full FAQ and TDS library.
- Mixed and used by application, not by coat-count. Mix 3 parts powder to 1 part cold water; mix only as much as you can use within about 20 minutes. Sandable after about 45 minutes; then finish with any LEINOS oil, wax or lacquer.
- It depends on the existing finish. Synthetic coatings must be fully removed. Old natural oil finishes can often be recoated after light sanding.
- Allow full curing time as specified in the product TDS, typically 7-14 days for full hardness, though the surface may be touch-dry much sooner.
- Check the specific product TDS for food contact suitability. Many LEINOS interior wood oils are safe for food contact once fully cured.
- Not if you match the tone. 337 comes in nine wood tones — white, ash, oak, natural oak, smoked oak, oak knot, cherry, beech and black — so you fill with the shade nearest your timber, sand it flush, and it reads as grain rather than a patch. A clear oil or wax warms the filled tone slightly, exactly as it warms the wood around it, so the two stay in step. For a visible repair, test the shade on an offcut first; our Delhi team will advise on the closest match if you send a photo or a sample.
- It is a dry powder you mix yourself — three parts 337 to one part cold water, stirred to a smooth putty that is ready at once and workable for about twenty minutes. It fills cracks, knots, nail holes, screw seats and gaps up to 15 mm deep in one pass on interior and exterior wood, sets hard by gypsum recrystallisation (so a deep fill does not shrink and drop out), and is sandable in about forty-five minutes. It is a cosmetic repair filler, not a structural adhesive — for structural rebuilds use a wood epoxy, and for mineral walls use LEINOS 684.
For Architects & Specifiers
Downloads
Technical and safety documents — citable in project specifications.
Need a Recommendation?
Talk to LEINOS
Four ways to reach our India team — pick the one that fits how you work.
Written by the LEINOS India technical team, in collaboration with
Reincke Naturfarben R&D, Lower Saxony.
Last updated
Want to represent LEINOS in your city?
Become a Dealer