What Type Of Coating Should I Choose For My Timber Floors?

A timber floor coating is an outer shell that protects floors from spills, scratches and wear and tear. Over time, the protective coating wears down and may need maintenance, but durability can vary depending on the finish of the floor. But what types of coatings are available and how do they compare? 

According to the Australian Timber Flooring Association,¹ the four main categories of timber floor finishes are:

1. Penetrating oils and waxes
2. Curing oils and alkyds
3. Oil modified urethanes
4. Polyurethanes

The last three categories are available in solvent-borne and water-borne compositions, and polyurethanes are available in non-yellowing (aliphatic) and yellowing (aromatic) varieties. All four have varying degrees of volatile organic (solvent) content (VOC), and gloss levels range from matt to high gloss finishes.

1. Penetrating Oils and Waxes

These timber floor coatings are blends of waxes and natural oils that have chemical salt ‘driers’ added. They are dissolved into spirit-type solvents, with some adhering to the Green Building Council of Australia guidelines² in terms of low VOC.

Although this coating involves maintenance — including regular applications of metalized acrylic polish — they are popular because they give timber a natural look that darkens significantly with age. 

2. Curing Oils and Alkyds

Curing oils such as linseed or tung are dissolved in white spirits or mineral turpentine and contain added chemical curing agents called ‘metal driers’. They have good edge bonding resistance, meaning they are resistant to ‘timber failure such as breakages. This is evident in floors that demonstrate significant structural variation or unevenness of lateral movement.

Gloss levels vary from satin to high gloss, and the finish produces a rich timber colour that darkens significantly with age. However, durability is low compared to other timber floor finishes, and they require regular maintenance with a metalized acrylic polish.

Alkyds are produced from combining curing oils with a synthetic resin, which is then dissolved into spirit-based solvents. This improves their durability and reduces maintenance. These coatings also provide good edge bonding resistance and a rich timber colour. 

3. Oil Modified Urethanes (UMO’s)

These timber floor coatings are spirit-based and solvent-borne and are made from a combination of oil with a smaller amount of urethane. The higher the urethane content, the more durable they are, and gloss levels vary from satin to high gloss finishes.

More recently, water-borne UMO’s have appeared on the market and although slightly more expensive, they have the advantage of having low VOC emissions.

Although all UMO’s yellow significantly with age, they are reasonably durable and generally free from issues like edge bonding. 

4. Polyurethanes

Solvent-borne polyurethanes are one of the most commonly used timber floor finishes, and offer the highest durability of all coatings. There are non-yellowing (aliphatic) and yellowing (aromatic) varieties and gloss levels vary from ultra high gloss to matt.

On the negative side, they have poorer edge bonding resistance, a strong solvent odour on application and a high toxicity content until the coating has cured. However, this can be alleviated with the correct use of personal protective equipment (PPE).

Water-borne polyurethane coatings offer the widest selection of sub-categories containing acrylic — from 100% polyurethane resins to polyurethane blends and co-polymer urethane acrylates. Blends can also include wax and silicone wear additives. Depending on the combination of properties, wear-resistance can vary dramatically.

They offer good edge bonding resistance, and both yellowing and non-yellowing types are available in matt, gloss, and other finishes which tend to darken less over time.

Regardless of the timber floor coating, some maintenance is required with all timber floors, and because flooring products vary considerably in their construction, so do their recommended cleaning requirements.

References

1. 2009, Timber Floors & Floor Finishes, Australian Timber Flooring Association
2. 2012, Compliance Guide For VOC, Australian Timber Flooring Association
3. 2016, Floor Care & Maintenance, Australian Timber Flooring Association