Working with native Australian timbers like Tasmanian oak and messmate often means dealing with sap lines and voids. These dark, vein-like cracks add visual interest, but when it comes to functional surfaces like tables or benchtops, they need to be properly filled for long-term durability. After testing countless methods, one approach consistently stands out as the most effective, durable, and easy to apply.
Why Common Fillers Fall Short
One widely used option is Timbermate Wood Filler in black. It’s easy to apply and relatively affordable, but it doesn’t hold up well in wet environments. On surfaces like kitchen tables or bathroom vanities, water can eventually seep through the finish and cause the filler to swell or fall out. For wet or high-traffic areas, this isn’t a reliable choice.
Liquid clear epoxy can look great, offering a glossy, professional finish. But it comes with serious downsides. Sap lines often run through the entire thickness of a board, and even with careful taping, epoxy tends to flow out through unseen gaps. Waiting for it to cure and doing another pour adds unnecessary delays and headaches—especially in a production setting.
Black epoxy glue is another potential option, but it can stain the surrounding timber, especially on fine cracks where it’s impossible to mask off the area. The heavy pigmentation is difficult to control and leads to a messy result on more delicate jobs.
A Better Solution: Techniglue with a Hint of Pigment
A more effective method involves using a non-flowing epoxy paste, such as Techniglue. It doesn’t run, it’s easy to store and reuse, and it offers complete control during application. The base colour is a honey tone—not ideal for most timber applications—but it can be tinted with a tiny amount of black epoxy pigment.
Here’s the trick: use a very small amount of pigment—about the size of a grain of rice per 60 grams of epoxy. This creates a rich charcoal colour that reads as black in the voids without leaving pigment stains on the surrounding timber. Since sap lines are already dark and don’t reflect much light, a translucent dark grey or charcoal fill is usually more than sufficient.
Application Tips
Mix the epoxy using a two-step method: start on a disposable surface, then transfer to a clean container with a clean stick. This prevents any unmixed residue from ending up in your filler and avoids uncured patches later.
Apply the tinted epoxy with a spatula, leaving it slightly proud of the surface. Once cured, sand it back using sharp, high-quality sandpaper like Abranet pads. Cheap sandpaper clogs quickly and wears out fast, leading to uneven sanding and wasted time.
The Final Result
With the right sanding technique and one coat of hard wax oil, the filled sap lines blend beautifully into the timber. The result is clean, natural, and incredibly durable. Unlike softer fillers, this method won’t swell with moisture or crack over time—making it ideal for high-use surfaces.