Finishing systems
There is a broad range of finishes available for timber floor systems. These can be broken into the following categories:

• Oil-based finishes – tung oil, modified tung oils, penetrating oils.
  
• Polyurethanes – solvent-based – single and two pack.
  
• Polyurethanes – water-based.

The selection of a suitable finish is based upon aesthetics, wear characteristics, maintenance and the ability to accommodate minor board movement.

Solvent-based Polyurethanes
Solvent-based polyurethanes are hard wearing, available in a range of gloss levels and are fairly quick drying. They have a tendency to physically glue the boards together when the coating works its way between the boards. The ramification of this is clearly apparent when the boards shrink slightly as atmospheric conditions become drier. The result is small groups of boards moving as one, producing a large gap, then another group of boards move as one, and so on. This is known as edge bonding, edge gluing, clumping or rafting. In extreme cases a board may be split as a result.

Water-based Polyurethanes
Water based polyurethanes are not quite as hard wearing as the solvent based variety. The product is gaining in popularity due to its rapid drying and very low odour. The propensity for edge bonding is lower than with the solvent based variety.

Oil-based Finishes
Oil based coatings are typically finished with a polish. The maintenance is higher than for the polyurethanes, and generally the gloss level is not as high as those achieved with the solvent based polyurethane product. Oil based finishes have a low propensity for edge bonding problems.

In all cases, the quality of the finish for timber floors will generally rely on the skills of the contractor. The sanding operation levels the floor surface, with a staged approach, starting with coarse paper and finishing with a very fine grit. The sanding should be uniform without any obvious grooves or swirl marks.

The coating of the boards shall follow the instructions of the manufacturer of the finish product. In all cases it is imperative to minimise any potential for dust or other foreign matter to contaminate the coating during its application. The floor will incur some minor blemishes to the finish over the years and can be expected to develop a softened patina.