Club demonstration — Wednesday 12 August  |  Presenter: Julie Gannaway (North Shore Woodturners / NAW)

Overview

Julie ran through a range of simple, low-cost ways to fill cracks and voids and to add decorative inlay to turned pieces — from everyday coffee grounds through to metal powders, coloured micro-pigments, and inlaid wire. The session was explicitly framed as experimentation rather than a single “correct” method: several techniques shown had mixed results on the night, which Julie treated as useful material in its own right. Samples up to ten years old, including well-used cheese boards and outdoor pieces, were passed around to show how each technique holds up over time.

Materials & Tools

Material / Tool	Notes
Ground coffee	Perked coffee, ground extra fine on a second pass — cheap, dark brown, works with most timbers
Cyanoacrylate (super glue)	Fast-curing; used to bind coffee, metal powders and wire; toxic fumes — ventilate and avoid sanding without a respirator
5-minute epoxy	Slower cure, doesn’t generate heat like super glue — better suited to heat-sensitive powders (e.g. aluminium) and bigger voids
Metal powders	Brass, aluminium, copper and turquoise (turquoise available in a couple of grit sizes plus a fine powder)
Micro/mica powders	Fine-pigment powders (craft/hobby suppliers, e.g. Carbotex) in a wide colour range, used in pyrography or laser-engraved grooves
Acetone	Keep on hand as a safety item — releases super glue from skin/tools
Application tools	Fine-tip applicator nozzles that come with super glue bottles; a cocktail stick or similar for working powder in (not fingers); insulin-style syringes for very fine, controlled super glue application; a small paintbrush for moving micro-powder
Wire (for wire inlay)	Solder wire or copper wire, in a couple of thicknesses
Parting tool(s)	Sized to match the wire thickness being inlaid

General Safety Notes

• Super glue fumes are toxic — work with adequate ventilation.
• Wear a respirator when sanding filled/inlaid pieces, particularly with metal powders.
• Use a stick or similar tool to work powder into glue — not fingers, both to avoid gluing yourself and due to toxicity.
• Keep acetone close by to free glued fingers/tools if needed.
• Seal the surrounding wood before applying super glue — unsealed grain will wick the glue and leave visible stain lines.

Technique 1 — Filling Cracks with Coffee

1. Seal the wood around the crack first — unsealed super glue will stain and telegraph through the surrounding grain.
2. Use finely ground coffee (perked coffee, run back through the grinder for an extra-fine grind). The dark brown tone suits most timbers.
3. Pack coffee grounds into the crack, then apply thin cyanoacrylate (super glue) through a fine applicator tip, letting it wick down into the grounds.
4. For bigger voids, pack with sawdust first, then coffee on top — coffee is cheap enough to use generously regardless.
5. Avoid accelerator sprays where possible — they can trap voids under the surface that only show up once you turn back into the fill.
6. Once cured, rub over with a finger — this grinds the coffee finer still and helps you feel out any remaining fine cracks.

Black-tinted super glue (available from club suppliers) is a simpler alternative to coffee on dark timbers and can read as natural grain. On lighter woods the coffee’s brown tone was generally preferred.

Longevity: samples shown included a cheese board with a ten-year-old coffee-filled crack, still sound after years of use and washing — provided the filled area isn’t load-bearing/structural, as timber movement can eventually reopen a crack regardless of fill.

Technique 2 — Metal Powder Inlay

1. Available powders: brass, aluminium, copper, and turquoise (turquoise comes in a coarser grit and a fine powder — grit can be used first to fill bulk, with powder used to fill remaining gaps).
2. Applied the same way as the coffee technique — pack the powder, then feed in thin super glue.
3. Apply in thin layers rather than all at once. Powder applied too thickly can leave a hardened surface film with loose, uncured powder still trapped underneath.
4. Caution with aluminium and pewter powders specifically: cyanoacrylate curing generates heat, and can exceed the melting point of these metals, leaving a dull, oxidised finish instead of a bright metallic one. Five-minute epoxy (which doesn’t generate heat) is a better binder for these two powders.
5. Copper and turquoise powders were shown as reliable, attractive fillers for burl voids and fissures — examples included a filled burl disc used as an inset panel and a decorative box lid using mixed turquoise grits.

Technique 3 — Micro-Powder (Mica) Inlay in Engraved Grooves

1. Cut fine decorative grooves using pyrography, or have a pattern cut with a laser engraver (settings — speed, heat, power — need adjusting per timber species).
2. Fill grooves with coloured micro/mica powder (a wide colour range is available from craft/hobby suppliers).
3. Bind with either super glue or 5-minute epoxy — both were demonstrated side by side for comparison. Epoxy was found generally easier to control and better suited to larger fills; super glue suited smaller, finer work.
4. A small paintbrush is useful for moving and placing micro-powder precisely, since it’s very fine and prone to going everywhere.
5. For very controlled, fine application of super glue (rather than a full applicator-tip stream), an insulin-style syringe gives much finer, drop-by-drop control — useful for filling narrow grooves one ring/section at a time without overflow.
6. Where a design has multiple colour zones, mask off completed sections before adding the next colour, or work from the centre outward, to avoid muddying colours together.
7. Once cured, sand back carefully — excess glue/epoxy on the surface cleans up easily, but avoid sanding through the full depth of shallow grooves.

Julie noted this technique is still a work in progress in her own practice — several samples shown had inconsistent results (air bubbles in epoxy fills, colours bleeding between sections), included deliberately to show realistic outcomes rather than only best-case results.

Technique 4 — Wire Inlay

1. Select wire (solder wire or copper wire both work; two thicknesses were shown).
2. Measure the wire’s thickness — this determines the groove size needed. Cut the groove slightly bigger and deeper than seems necessary, as it typically needs to be more generous than expected.
3. Cut the groove using a parting tool sized to suit — have a couple of parting tools of different widths on hand to match different wire gauges.
4. Seal the wood before gluing (as with the other techniques).
5. Lay the wire into the groove with super glue, working it in with patience — the first section takes a moment to tack down, after which the rest follows more easily.
6. Once glued, peen/hammer the wire to spread and flatten it into the groove, fully filling the channel; a smooth file can also be used instead of a hammer for a flatter, more finished face.
7. Trim any excess length once secure, then true up on the lathe.

Durability: Julie’s original outdoor coffee table inlay pieces lasted roughly eight years outside before the surrounding timber eventually cracked — notably, the wire itself stayed firmly in place the entire time.

Variations mentioned: twisted wire (by hand or with a drill for a tighter, more even twist) for a decorative pattern; aluminium powder can be used to dress/fill a slightly proud joint in the wire before final finishing.

Closing Notes

• None of these techniques are presented as the only or “correct” way — Julie encouraged experimenting and adapting them to individual style and the piece at hand.
• Keep a small dedicated box of filling/inlay supplies near the lathe so a crack encountered mid-turning can be dealt with immediately rather than becoming a separate trip/session.
• Bringing imperfect or “failed” examples to a demo was called out as valuable — seeing what goes wrong is as instructive as seeing a finished piece.