Independent comparisons. We may earn from shop links. More info

How to use wood filler without a sunken repair

Updated: October 2026

You have a tub of sandable paste, a hole in sound timber and a finish to apply afterwards. Knowing how to use wood filler is mainly about preparation, coat depth and waiting until the centre is hard, not forcing a convenient clock onto a thick fill. This guide covers ready-mixed paste rather than wax or kneadable epoxy. If you have not chosen the material yet, use the [wood filler buying guide](/hub/paints-and-varnishes/wood-putty/sub/wood-putty-buying-guide) or compare the products in the main [wood putty comparison](/hub/paints-and-varnishes/wood-putty). The reliable sequence is to clean and dry the hole, pack the paste slightly proud, respect the depth stated on your tub, then sand and test the intended finish only after curing.

You have a tub of sandable paste, a hole in sound timber and a finish to apply afterwards.

Our top picks

Milliput Milliput Standard, yellow/grey

Best overall

Milliput Milliput Standard, yellow/grey
9.4/10about £5.24
View offer
Everbuild Everbuild light stainable, 250 ml

Best value

Everbuild Everbuild light stainable, 250 ml
9.0/10about £4.69
View offer
Mollor Mollor white paste, 150 g

Rank 3

Mollor Mollor white paste, 150 g
8.6/10about £9.99
View offer
On this page
  1. 1.Clean, dry the wood and pack the fill proud
  2. 2.How deep one coat can go
  3. 3.Sand when it is hard, not when it is convenient
  4. 4.Paint is simpler than stain

Clean, dry the wood and pack the fill proud

Start by deciding whether the timber is sound enough to fill. Remove loose fibres, flaking paint and crumbling old filler with an appropriate scraper or abrasive. The hole should be dry before paste goes in; trapping moisture beneath a repair is particularly risky on a window frame or sill. Press filler firmly into the deepest part of the recess rather than skimming over its mouth, and finish a little above the surrounding timber. If you level the paste perfectly while wet, the centre may finish hollow and require another coat anyway. If the timber feels soft beyond the edge of the hole, stop. The exterior wood filler guide sets out that stop rule.

How deep one coat can go

The allowable depth depends on the product, not on a universal rule for wood filler. Everbuild's technical sheet limits its multi-purpose ready-mixed paste to 5 mm in one coat. Polycell publishes a 10 mm layer for one of its own wood fillers, but that figure belongs to that product and should not be transferred to an Everbuild tub. A 12 mm recess needs several controlled layers, each dried as instructed, or a product designed for deeper filling. Mollor's listing says directly that a large fill can sink and should receive another layer after drying. Do not add hardener to a one-part ready-mixed paste. If the job is not small enough for paste, return to the job-by-job shortlist.
Milliput Milliput Standard, yellow/grey

Testsieger

Milliput Milliput Standard, yellow/grey
9.4/10about £5.24
View offer

Sand when it is hard, not when it is convenient

Drying times are conditional. Everbuild states approximately 15 minutes to touch-dry, 30 minutes to sand and two hours to through-hard at 20 °C. Those figures describe the maker's conditions, not a guarantee for a cold workshop, a damp recess or an over-thick coat. Touch-dry only describes the surface. Before sanding, check that the repair resists a gentle fingernail press at the edge; this is a practical rule of thumb, not a substitute for the label. Sanding produces a mixture of dried filler and wood dust. HSE gives workplace exposure limits of 3 mg/m³ for hardwood dust and 5 mg/m³ for softwood dust as eight-hour averages. Those figures are occupational limits, not a home permission to create dust. If the centre has sunk, clean it and add another thin layer; do not try to hide a depression with paint.

Paint is simpler than stain

Opaque paint hides colour differences, although it does not hide poor levelling. Once the filler is fully dry, sanded and dust-free, apply the primer or paint system recommended for the timber and filler. Temperature, depth and coating type can all justify more time than the shortest listed interval. Stain exposes the repair because filler has no natural grain and can absorb pigment differently. Everbuild advises matching filler to the wood rather than to the stain and notes that the paste may dry darker. A label saying stainable therefore means the coating can be applied, not that the patch becomes invisible. The wood filler versus wax sticks guide helps when the film is already finished. For exterior work, Everbuild requires fresh exterior fills to be kept out of rain for at least five hours and says not to apply below 5 °C.

Common questions

Should I fill level or leave wood filler proud?
Leave ready-mixed filler slightly proud of the surrounding timber, then sand it level after it has dried hard. Water-based paste can shrink as moisture leaves. Keep the overfill narrow and local, because a wide smear creates unnecessary sanding and makes a visible stain-grade patch larger.
How thick can one layer be?
Use the number on your product. Everbuild Multi-Purpose and Ronseal Multi Purpose specify about 5 mm per layer, while a Polycell product permits 10 mm. Do not copy one maker's depth onto another tub. Build a deeper repair in dried layers or choose a two-part product designed for depth.
When can I sand Everbuild wood filler?
Everbuild gives about 30 minutes to sand and two hours to through-hard at 20 °C, with touch-dry at 15 minutes. A colder room, thick coat or damp substrate can extend that. Confirm that the centre is hard and follow the tub rather than sanding solely because the minimum time has passed.
What should I do if the fill sinks?
Let the first coat dry fully, remove loose dust and apply another thin layer slightly proud. Do not cover a soft or hollow centre with paint. Repeated sinking suggests that the coat is too deep, the product is too wet for the job, or the void needs a different repair system.
How do I test stain?
Create a small sample using the same filler, timber preparation and drying time. Sand it, apply the intended stain and then the clear finish if one is planned. Judge it only when dry. A stainable claim does not guarantee that filler and natural grain will absorb colour identically.
When should a professional take over?
Ask a joiner when timber is soft over a wide area, a sill or frame has lost substantial section, a stair component moves, or moisture continues to enter. Filler is appropriate for local damage in sound wood. It cannot correct rot, structural movement or a leaking building detail.

Related pages

Wood putty

Best wood filler UK: match each listing to the job

Wood filler or wood putty: which type should you buy

Exterior wood filler: when the sill is safe to fill

Wood filler vs wax sticks: chips, scratches, floors

Sources

Public UK sources and maker sheets used for the limits on this page. Prices, stars and review counts are the amazon.co.uk listing figures for the ten products compared here.

  1. Leyland SDM — wood fillers guide (retrieved 17 October 2026)
  2. Ronseal Multi Purpose Wood Filler (retrieved 17 October 2026)
  3. Ronseal High Performance Wood Filler (retrieved 17 October 2026)
  4. Everbuild multi-purpose wood filler technical data sheet (retrieved 17 October 2026)
  5. Milliput — how to use (retrieved 17 October 2026)
  6. HSE — wood dust (retrieved 17 October 2026)
  7. VOC in Paints, Varnishes and Vehicle Refinishing Products Regulations 2012 (retrieved 17 October 2026)
  8. Consumer Rights Act 2015, section 9 (retrieved 17 October 2026)