For most of the 20th century, finishing timber meant polyurethane. Hard, glossy, protective — and fundamentally disconnected from the material beneath. A thick coat of PU lacquer doesn't protect wood so much as it replaces it visually, sealing the surface behind a plastic layer that eventually yellows, peels, and needs stripping before any maintenance is possible.
The natural oil and hardwax revolution of the 2000s changed this logic. Oils penetrate the wood fibre rather than sitting on top of it, protecting from within while allowing the grain to breathe. When they wear, they wear gracefully — and maintenance means reapplying oil to affected areas, not stripping and refinishing the entire surface. For architects working with exposed timber as a finish material, this is not a minor improvement. It is a fundamentally different relationship with the material.
Rubio Monocoat: the Belgian precision system
Rubio Monocoat was founded in Belgium in 2009 and has since become something close to a cult product among architects and interior designers who work with exposed wood. The core innovation is a single-component system using modified plant oils that bond molecularly with the wood fibre — meaning the oil literally becomes part of the wood, rather than sitting on top of it.
The flagship product is Oil Plus 2C: a two-part system (the oil and an accelerator hardener) that cures in 24 hours and provides a durable, water-resistant surface in a single application. No second coat is required or recommended — applying more than the recommended amount actually reduces performance, because the oil can only bond to the available wood fibre.
The colour range is extraordinary: 60+ standard colours from Pure (natural) through a full spectrum to the new Smoke, Mountain, and Cotton collections. Each colour behaves differently on different species — Rubio provides a sample chip system that allows proper colour confirmation before committing to a large floor area.
Osmo: the German engineering approach
Osmo Holz und Color has been producing plant-based wood treatments in Germany since 1932. Where Rubio's system is minimalist — one product, one coat — Osmo builds a comprehensive system of primers, base coats, maintenance oils, and specialty products designed to address every wood type, application, and environment.
The core of the Osmo range for architects is Polyx-Oil: a hardwax oil combining plant oils (sunflower, soya, thistle) with natural waxes (carnauba, candelilla). It provides a more conventional two-coat application and results in a finish that is slightly more sheen and slightly more wear-resistant than Rubio in high-traffic applications. Available in clear and tinted variants including White, Grey, Terra, and Ebony.
For exterior timber — decking, cladding, external joinery — Osmo's UV Protection Oil range has a track record that is difficult to match. It is available through a network of Osmo distributors in Spain and across the EU.
Head-to-head: the key differences
| Criterion | Rubio Monocoat | Osmo Polyx-Oil |
|---|---|---|
| Coats required | 1 coat | 2 coats |
| Cure time | 24h light use, 7 days full cure | 6h recoat, 3 days full cure |
| VOC content | Zero VOC | <1g/L (EU Ecolabel) |
| Colour range | 60+ colours | 40+ colours + custom |
| Exterior use | Limited (specialist range) | Full exterior range |
| Price (coverage) | €89 / 40m² | €68 / 25m² |
| Available in Spain | Online + select dealers | Nationwide distributor network |
Our verdict
Choose Rubio Monocoat for interior residential timber — floors, joinery, furniture, and exposed CLT. The single-coat application is genuinely time-saving on large areas, the zero-VOC formula is ideal for occupied spaces, and the colour range is unmatched for interior design projects where the finish tone is critical.
Choose Osmo for exterior applications and for high-traffic commercial interiors where maximum wear resistance is the priority. Osmo's distributor network in Spain is also more established, which matters if you need consistent supply across multiple project phases.
Both products are significantly better for the environment, for the building occupant, and ultimately for the timber itself than any conventional polyurethane lacquer. Either choice is a good one.
Affiliate disclosure: This article contains affiliate links to Rubio Monocoat and Osmo. Soul Materials only recommends products independently evaluated by our editorial team. Commissions support our work at no additional cost to you.
