Hobson technical article
Ruspert Coating on Screws: R1000 and R1500 Explained
A two-page Hobson technical article on Ruspert, a multi-layer zinc and baked ceramic coating for fasteners. It explains the layers, salt spray grades, contact corrosion, use in treated timber, and how it compares with zinc plating, mechanical galvanising and hot dip galvanising.
What this covers
- Coating layers
- Salt spray grades
- Contact corrosion
- Treated timber
- Comparison with zinc and galvanised
- Baking process
Applies to Concrete Screws (Screw Anchors), Roofing & Cladding Screws and Tek Screws (Self-Drilling Metal Screws).
Key things to remember
The essentials from this document in plain words. Check the full document before you rely on a figure.
- Three layers: free zinc next to the steel for sacrificial protection, a chemical conversion layer, and a baked ceramic top coat as a physical barrier.
- Graded by neutral salt spray hours before red rust: R500, R1000 or R1500. Hobson's Ruspert products are R1000 or R1500.
- The article compares R1000 to a Class 3 screw (outdoor use in mild to moderate industrial or marine environments) and R1500 to a Class 4 screw (severe marine environments).
- The ceramic top layer is non-conductive, so the zinc only protects the fastener itself. This avoids contact corrosion with other metals, for example stainless screws into aluminium.
- Suitable for treated timber, which needs at least a Class 3 coating on screws. Zinc plating (about 5 microns) is for indoor, low corrosion use only and is not recommended for treated pine.
- Baked at under 200°C, so the steel's mechanical properties are kept. Its abrasion resistance suits concrete screw anchors that cut their own thread.
Who it helps: Anyone choosing a screw or concrete anchor coating for outdoor, coastal or treated timber work.
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