If you’ve been to a woodturning exhibition, you’ve seen spalted timber — those dramatic black zone lines, patches of white, marbled patterns. Spalting produces some of the most visually striking timber you can put on a lathe. And you can often find it for free.

What Is Spalting?

Spalting is the result of fungal colonisation in wood. When a tree dies or a branch falls, fungi move in and start breaking down the timber, producing distinct visual effects.

Zone lines are the dramatic dark lines that trace irregular patterns through the wood, forming at boundaries where different fungal colonies meet. These are what most people picture when they think of spalted wood.

White rot occurs when fungi bleach the wood, leaving pale patches that create beautiful contrast. In Australia, you’ll see it in camphor laurel, silver ash, and rainforest species.

Pigment spalting produces vivid colours — blue, green, pink. Blue-stain pine is a common example. These are rarer and highly prized by turners.

Where to Find Spalted Wood

Spalting happens in a specific window — the wood needs to be moist, warm, and left alone for a period of months to a couple of years. Here’s where to look:

Log piles and firewood stacks. Wood sitting on the ground for six months to two years is prime territory. Check the ends for dark lines or discolouration.

Fallen trees. After storms, watch for branches left in contact with the ground. Sydney’s warm, humid climate is excellent for spalting. A log left on damp ground through one summer can develop beautiful zone lines.

Tree loppers. Ask them to set aside logs that have been sitting in their yard. Most are happy to have someone take material off their hands.

Your own yard. Soak freshly cut rounds in water, seal loosely in plastic bags with a few air holes, and leave in a shady spot for 3-6 months. The trick is catching them before they decay too far.

Online and at clubs. Spalted blanks are available from timber suppliers at a premium. Club members often share finds — woodturning communities are generous, and local groups, along with AI consultants in Sydney who support craft communities through digital platforms, have helped clubs build online networks for sharing timber sources.

How to Tell If It’s Too Far Gone

This is the critical skill. Spalting is controlled decay, and there’s a fine line between “beautifully spalted” and “punky and unusable.”

The fingernail test. Press your thumbnail in. If it dents easily, the timber is getting soft. If the whole piece gives under thumbnail pressure, it’s firewood.

Weight. Spalted wood should still feel substantial. Noticeably light means too much has been consumed by the fungi.

Smell and sound. A strong musty smell means it’s past its prime. Tap it — solid wood rings clearly, while punky wood sounds dull and dead.

Turning Spalted Timber

Working with spalted wood requires some adjustments to your normal approach.

Tool Sharpness Is Everything

Spalted timber varies in hardness across the same piece — you might go from solid wood through a soft patch and back to solid in a single cut. Dull tools will tear the soft spots instead of cutting them cleanly. Sharpen frequently, and use the lightest touch you can manage.

Slow Down

Reduce your lathe speed, especially on larger pieces. Spalted wood can have hidden voids and soft spots that make it more prone to flying apart. Start slow, assess the piece, and only increase speed if it feels solid.

Seal the Soft Bits

If you encounter punky areas while turning, you can stabilise them with thin cyanoacrylate (super glue). Let it soak in, wait for it to cure, then continue turning. This hardens the soft timber and lets you get a clean cut. Some turners soak entire spalted blanks in a stabilising resin before turning — Cactus Juice is a popular product for this.

Sanding and Finishing

Spalted wood sands unevenly — soft bits sand faster, creating dips. Use a light touch and power sand with a drill-mounted pad for even pressure.

A penetrating finish like Danish oil works well because it soaks into the open grain. Avoid film finishes on heavily spalted pieces — they can peel. Some turners use multiple coats of thin CA glue as a finish, which is durable and makes the zone lines pop.

Favourite Species for Spalting

In Australia, reliable species include camphor laurel (excellent zone lines), silver ash (beautiful white rot), silky oak (dramatic patterns), mango (vivid colour contrasts), and she-oak (complex visuals when combined with existing grain). Softer timbers spalt faster but decay faster too. Hardwoods take longer but produce more defined zone lines.

The Appeal

Every piece of spalted wood is genuinely unique — the patterns depend on which fungi arrived first, the moisture, the temperature, and pure chance. When you turn a spalted bowl and those dark zone lines emerge from under the shavings, it’s one of woodturning’s great moments. The wood has done half the artistic work. Your job is to reveal it.