Crushed glass, walnut shell or soda: choosing media for wood

On steel the media choice affects speed. On wood it decides whether the job is a success or a permanent mistake.

Recycled crushed glass

Our default for log and timber work. Silica-free, angular enough to cut stain and paint efficiently, and light enough that at low pressure it lifts the finish without carving the soft spring growth. It is also the most economical option, which matters on a whole-house job.

Crushed walnut shell

Softer and gentler. The right answer for carved work, ornate detail, very old timber, or anywhere the surface texture is part of what you are preserving. Slower and more expensive, so it is usually a targeted choice rather than a whole-wall one.

Soda

Very mild, good for mould, mildew and light coatings. It gets recommended online more than it deserves for stain removal — the results are inconsistent, and residual soda can interfere with some finishes if it is not neutralised properly. It is not our default.

The media is only half the decision. The same crushed glass at the wrong pressure will still ruin a wall.

Pressure is the other half

Wood work runs at a fraction of the pressure we would use on structural steel. We test an inconspicuous section on every house, check the take-off rate and the grain condition, then set the wall.

The softwood on the newer cabins around Elkwater takes a lighter hand than the older, harder timber on some of the farmhouses out toward Irvine and Walsh. Same machine, different media and pressure.