Varnishing Pine Floors: A Practical Guide
Pine floors are one of the most common wood floors in the UK, found in Victorian and Edwardian terraced houses, period cottages and older residential properties across the country. They are also one of the more challenging wood floors to varnish well, because pine has characteristics that require specific preparation steps not needed for hardwoods like oak. Understanding these characteristics and addressing them properly produces a varnished pine floor that looks excellent and lasts.
Pine's Specific Challenges
Pine contains resin channels and knots. Knots in particular are a potential problem in floor finishing because the resin in and around them can bleed through varnish coats, especially oil-based products, appearing as sticky or discoloured patches on the surface. Modern water-based floor varnishes are much less susceptible to resin bleed than old oil-based products, which significantly simplifies the varnishing of pine floors.
Pine also has prominent grain with alternating hard and soft grain bands. This can cause differential absorption of oil-based products, with the softer grain bands absorbing more than the harder ones and producing a slightly uneven finish. Water-based varnishes tend to be more consistent across pine's varied grain density.
Older pine boards in period properties often have nail holes, filled gaps, surface grime and possibly old paint or stain residues. All of these need to be addressed before varnishing produces a consistent result.
Preparation for Pine
Begin with a thorough sanding using 40-grit to strip any existing finish, followed by 60-grit and 80-grit for the final surface. Pine is a softer wood than oak and sands relatively quickly; be careful not to create deep machine marks with the initial coarser grits.
For knots, apply a shellac-based knotting solution before the first sealer coat. This seals the resin in and around the knot and prevents it from bleeding through the subsequent varnish. Bona Knotting Solution or Morrells Knotting Solution are available from flooring suppliers. Apply by brush directly to each knot and allow to dry completely before sealing.
Choosing a Varnish for Pine
Water-based varnishes are the best choice for pine. They do not exacerbate resin bleed and they dry clear without the amber warmth of oil-based products, which can make pale pine look more yellow than desired. Bona Traffic HD in extra-matt or satin produces an excellent result on pine: it enhances the natural colour without significantly changing it, and its durability copes well with pine's relative softness compared to hardwood species.
Pine boards, being softer, are more susceptible to indentation and scratching than oak or ash. A high-build varnish system (three coats minimum) provides the best protection. The additional film thickness of three coats helps absorb minor impact without the indentation reaching through to the wood surface.
- Apply knotting solution to all knots before the sealer coat
- Use water-based varnish to avoid resin bleed problems
- Sand through 40, 60, 80 grit sequence
- Apply minimum three coats for adequate protection on soft pine
- Bona Traffic HD in matt or extra-matt: excellent choice for pine floors
- Fill nail holes with colour-matched filler after first sanding and before varnishing
A well-varnished pine floor is one of the most satisfying results in floor finishing. The boards' natural variation, the pattern of the grain, the character of the knots and the warm tones of the timber all become visible through a quality clear varnish. The preparation effort required is justified by the result, which can transform an overlooked Victorian pine floor into one of the most attractive features of the room.