Timber is a beautiful, versatile building material that’s been used for thousands of years to construct a range of items including floors. However, in order to keep timber floors functioning at their best, they need to be protected from things like weathering, moisture, abrasion, chemicals, mould and fungi. Timber finishing can help to not only protect the surface of a wooden floor but embellish its properties as well.
Here is an expert guide to the different types of wood finishes.
What Are The Categories of Wood Finishes?
There are three main types of timber finishes – evaporative, reactive and coalescing. Evaporative finishes use acetone, alcohol and nitro-cellulose lacquer thinners as solvents and thinners. Shellac and nitro-cellulose lacquers also fall into this category.
Solids are string-like and soft in solution, but as the solvents evaporate they begin to lock together in a solid mass. Successive layers then burn into one another and form a contiguous whole, meaning they share a common border. Solvents can re-soften the film – for example, alcohol softens cured shellac and lacquer thinners will soften cured lacquer.
Cellulose thinners and polishes and lacquer and lacquer thinners are basically in the same family of finishes. Lacquer thinners (also known as cellulose thinners) also come in different types, for example, as ‘slow’ or ‘cool’ or ‘fast’ or ‘hot’ thinners depending on how the formulation is supposed to perform. Wax is an evaporative finish because it’s dissolved in petroleum or turps and distillates to make a soft paste. Once these distillates evaporate, all that remains is the wax.
Reactive finishes use solvents like naphtha and white spirits. Linseed oil and oil varnishes are also reactive finishes that chemically change when they cure (unlike evaporative finishes). As they cure, the thinner/solvent evaporates and the resins cluster together tightly, a chemical reaction then occurs which causes the resins to crosslink in a different chemical format.
Floor sanding is normally necessary between the layers of cured finish so the subsequently applied layers have something effective to grip onto. The solvent also won’t re-dissolve the cured film, so for example, white spirits don’t soften cured oil-based varnishes. Linseed oil and tung oil (also known as China wood oil) are also reactive finishes that cure by reacting with oxygen, but they don’t really form film finishes when they’re cured.
The last type of finish is called a coalescing finish, and water-based finishes generally fall into this category.
What About Timber Staining?
Timber stains consist of a colourant dissolved or suspended in a solvent. The suspension agent can be alcohol, water, petroleum distillate or the actual finishing agent, whether it’s lacquer, shellac, varnish or polyurethane. Stained finishes like polyurethane don’t penetrate the pores of the wood to any large degree, so will disappear when the finish itself is removed intentionally or it deteriorates.
In terms of colourants used for timber staining, both dyes and pigments are used and the difference comes down to the size of the particles. Dyes are made up of microscopic crystals that dissolve in the substance, and unlike pigments that only attach themselves to wood, dyes will colour fine-grained wood (like maple and cherry). Dyes are generally translucent and pigments are opaque.
Stains will either obscure the wood grain or accentuate it, and most commercial stains contain both pigment and dye. The degree to which they stain the appropriate wood is mainly dependent on the length of time they’re left on the wood. Pigments, regardless of the suspension agent, won’t give much colour to very dense woods, but will deeply colour woods with large pores like oak. Gel stains are more like paint and have very little penetration ability when it comes to timber finishes for floors.
What Are Some Of The Newest Developments?
In terms of timber floor finishes and some of the protective coatings for wood, technologies are improving all the time with some of the more recent developments being:
Slip-resistant surfacing – The surfaces of wood can be very slippery when wet, whether the timber is on stairs, ramps, decking or walkways. Anti-skid paint works by the inclusion of a non-slip aggregate or by creating a rough surface that offers more grip in both dry and wet conditions.
Need a hand with finishing your newly installed timber floor or your existing timber floor? Contact the experts at Brisbanes Finest Floors today on 0411 220 488.