Timber fencing is more porous and softer than colorbond, meaning it can be etched or splintered under excessive pressure, and painted or stained timber runs the additional risk of the finish being stripped if pressure isn't carefully controlled.
Colorbond steel fencing generally handles higher pressure well since the surface is hard and non-porous, but it's still worth avoiding direct, close-range blasting on any areas with scratches or exposed edges where the protective coating may already be compromised.
Both benefit from the same underlying goal, removing mould, dirt and grime buildup that develops faster in shaded, damp sections, but the technique and pressure level genuinely need to be matched to the material to get a clean result without unintended damage.
