On Fillers and fixes

There are many options for filling voids and defects, bad joints and more. Do they work? Should we?

I think I have invented one or two of my own and then had a thousand recipes from woodworkers telling me what they do to give the impression of a perfect dovetail or shoulder line to a tenon. The most common suggestion is glue and saw or sanding dust. This makes a filler but of course, even in the same wood, the colour will not match. In some places, a contrast will work acceptably well. I might go for a very deliberate contrast rather than a close or perfect match in some cases simply because I know that working on new wood a match can be good but over a few weeks the main body of wood will change colour in the light but the filler will not. In that case the filler becomes obviated by its inability to change.

The whole of

I don’t really want to get into commercially made fillers but more of what works at the bench in the instancy of the moment so that I can get on with planing, paring, sanding and finishing. This weekend I had several filler-and-fixer needs. Knots are common enough and especially dead knots like the one below. Often the knot is fairly firm but some of the wood is pithy and punky. I usually leave as much of this rotted wood in place as possible but leaving it alone and putting on the finish will not resolve its lack of integrity and integration with the main body of wood simply because the sub-fibres of the rot are weak and mostly fractured. This I first resolve with a super-thin CA (super) glue which hardenes the compromised knot to make it knot-hard again.

The CA glue wicks into the fibres through gravity and capillary attraction . . .

Applying the liquid directly to the knotty area allows the fluid to pull itself into the fibrous area. A second application a minute after, will leave a heightened area above the surrounding wood.

. . . the second application bulbs up on the surface and I remove any excess with a paper tissue making certain not to stick my fingers with the glue.

If you leave the glue to itself for ten minutes more or less the glue will self-harden but you can also use a light misting of accelerator which hardens everything off in a matter of a few seconds and you can get on with the leveling and finishing.

Use a card scraper to scrape down any excess flush with the surrounding surface but don’t sand at this stage, it’s not necessary. I have always liked the idea of minimising sanding and relying more on card and cabinet scrapers which give as good if not a better surface when the scrapers are sharpened correctly and kept sharp.

The card scraper works exceptionally well for taking off the hardened CA glue by [resenting it at a low angle and pulling.

I have always preferred wax filler sticks for a wide range of filling and fixing needs. You can intermix the colours for a match to the area you need and the collou remains the same long term. This is where I filled the void with a wax filler rather than more messy epoxy or transparent super glue which I often do too.

Press in the wax with a plastic spatula that usually comes with wax fillers.

A last pass with the card scraper levels everything and you have a great fixup ready for applying the finish.

Search on somewhere like Amazon for wax furniture fillers. There are dozens to choose from. Some expensive and some in a pack of six light wood shades, another in medium shades and another in six dark wood shades. You can get packs of fifty different shades if you want them. The main thing to remember is that most woods darken over the years when exposed to light but then some woods lighten. The choice you make now will possibly stand out later but that is the same with any wood filler.


  1. I’ve used super glue, particularly for resinous patches but I didn’t know about wax fillers. I’ll be investing in some.
    Another way I hide a defect is……don’t tell anyone. It probably won’t be noticed.

  2. I remember seeing some pieces of furniture where dead knots had been cleverly repaired by drilling out, presumably using a forstner bit and then glueing in a small piece of branch wood from the same species to give the impression of a live knot.

  3. A question to a related problem. I’m working on the tool-drawer organiser project. The front panels of the drawers will be in nordic black adder: Alnus glutinosa. One of the panels has, not a rotten knot, but the hole where one was. Not quite thru the plank but probably over halfway. The hole/ indent is 8-9 mil in diameter. I do really like the patterns on the panel. So how to redeem this one: The Vax filling method, a fitted dowel glued in the hole or something else?

  4. I discovered the hard way that CA glue can reach very high temperatures when curing, especially when treated with accelerant or in contact with cotton. I sustained a very painful burn through the full thickness of a fingernail after wiping excess glue off with a cotton rag scrap. Googling the matter showed that severe burns have been sustained by children spilling CA onto cotton clothing they were wearing. So if you didn’t already know, heads up!

    1. Whereas in general the CA glue cures without generating excessive and dangerous heat when not using an accelerant, it can generate high temperatures on certain materials including some woods. The accelerant does induce high temperatures every time and everyone should be aware of that. I understand that CA (superglue) glue was initially developed to bond skin for military personnel injured in situations where immediate help might not be available, for small cuts and such, so i5t is important to be aware of the dangers. Thank you for the nudge Philip.

      1. I too have experienced the intense heat generated by CA when wiping it away with a cloth wrapped around my finger. I had to rapidly tear away the cloth to prevent a really severe burn. So now, I never wrap the cloth around my finger as shown in your photo. Instead, I hold the cloth further back. Might I suggest that you consider changing your photo to reflect this?
        Thank you.
        Kind regards

  5. I do wonder what the process is for timbers with larger quantities of defects such as burr/burl (veneer or otherwise) and catspaw that you see on vintage pieces.

    would you still fill each imperfection with wax or is the system different for these larger areas of voids?

    1. Vintage fillers often used shellac mixes with fibres from the wood as in sawdust. In our today woodworking, people often use a slow-cure epoxy that gives a very hard surface, West Systems works great over many hours, or an acrylic too.

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