Metallic marks are removed using a mild acidic gel: Oxiclear.
Rust marks can appear on white render from vents and various fixings. Lead milky run offs are common on slates and occasionally on glazing. Oxiclear will clean old lead of it’s toxic powdery surface if present or brown oxide. It will remove copper oxide and clean copper components and decorative features.
Oxiclear is designed for longer contact times on vertical surfaces. It does not penetrate the substrate.
The gel prevents evaporation and stabilises the active surface concentration throughout the process.
Timing the dwell time will help in controlling the effects. The gel lubricates the surface when brushed, limiting the risk of scuffing on fragile surfaces. It is low odour and rinses readily.
Other use: General cleaning of GRP and plastics.
Warning: The active ingredient is phosphoric acid and will damage some alkali paving stones. A test is necessary. On render over exposure to the gel will result in a light discolouration.