Timber floor finishes can be grouped into four broad categories. These are the oil-based finishes, composite finishes (mixes of oil-based and solvent based polyurethane finishes), solvent based polyurethane finishes and water based finishes. With time all finishes will change in colour and film build as the finish wears. Therefore the ability to touch up becomes more difficult with time, however all coatings can be restored by recoating. In the long term a re-sand and refinish may be necessary depending on the wear and age of the floor.
Oil-based finishes are the more traditional types of finish manufactured by reacting a natural oil (e.g. linseed and tung) with another chemical. Varnishes and the traditional oils fall within this category and are associated with the polished and waxed timber floors of the past. These types of finishes are still available and require greater regular maintenance than the other finishes. However they are easier to maintain. These finishes will darken with time.
Finishes containing oil-based alkyds with the addition of urethanes provide a finish with reasonably good abrasion resistance. Oil modified urethanes and many of the ‘tung oil’ based finishes are of this type. The odour during application is very strong but dissipates as the finish dries. These finishes provide a subdued, satin to semi-gloss appearance. They darken with time and require more frequent maintenance particularly in high traffic areas. Acrylic floor polishes may be used to protect the finish.
Solvent Borne Polyurethane Finishes
Solvent based polyurethanes (one pack and two pack) provide a harder finish, generally with limited flexibility but much greater abrasion resistance. Consequently, this greatly reduces the level of routine maintenance. They currently provide some of the hardest finishes available today with gloss levels from matt through to a very high gloss. These finishes, as with the oil-based finishes, will generally darken with time. The odour during application is very strong with these products but dissipates as the finish dries. Due to their high strength and generally limited flexibility, edge bonding of boards can occur.
Water based polyurethane/acrylic mixes (one and two pack) with very good wear resistance(comparable to solvent borne) are very popular. These finishes are generally applied over a sealer, that not only enhances the colour of the timber but can significantly reduce the risk of edge bonding. Matt through to gloss finishes are available and these finishes generally darken little with time. During application there is low odour associated with water based finishes. A curing additive (catalyst) may or may not be recommended by the manufacturer.
The following table outlines the types of finish available and lists various characteristics of each.