There are a range of varnishes on the market, from natural products to chemically developed polyurethane varnishes. Picking the right varnish for your furniture finishing or woodwork projects isn’t as straightforward as it used to be in the days when only tung or linseed based varnishes existed. Current varnishes are variants of traditional century old products, although the market is dominated by polyurethane varnishes.
It is well known that varnish has been in use for hundreds of years, and hasn’t lost its popularity. In particular, varnish is the wood finish of choice when you would like to prevent surface scratching and would like the natural grains of the wood to be visible.
Although the two primary oils that are used in varnish are still tung or linseed, the processes that are used to chemically produced varnishes consist of three basic ingredients. The first of course, the oils we have mentioned. The other two key ingredients are resin and solvents. It is mostly the ratios between these ingredients, especially the ratio of resin to oil, as well as the type of oil and resin that is used that defines the characteristics of most varnishes.
- An Oil base, either Tung or Linseed Oil
- A Resin base, either Phenolic, Alkyd or Polyurethane
- A Solvent
The solvent determines the flow of the product, it’s drying time (based on how quickly it evaporates). The resin, which could be one of phenolic, alkyd and polyurethane resins, defines the protection of the finished product. The most common varnish is usually of polyurethane base, mostly due to it being cheap to produce. However cheap doesn’t immediately mean low quality, many polyurethane varnishes have high resistance to scratches and come in clear coatings, making them suitable for most basic finishing. Phenolic resin on the other hand is usually used in the more luxury end of varnish or wood finishes and as a result you will find a decent presence of phenolic in costly varnishes. Similarly, Tung oil is the costlier of the two varnish oils and as such Tung based varnishes tend to cost more than linseed oil based varnishes.
Things To Consider When Selecting The Best Varnish
The best varnish to choose of course depends on a range of criteria, from the end product usage to budgetary constraints. However it isn’t uncommon to find one than more oil or resin combination in a varnish.
Indoor vs outdoor
Some varnishes are made for indoor products, while other specialist varnishes are formulated with additional UV protection and high oil content for products used outdoors.
Wear and Tear
If your furniture is going to be in use regularly, or even heavily, you ought to consider a harder varnish for say an item that is decorative.
Look and Feel
As explained earlier, some varnishes are quite cheap, while some are fairly costly. If you are varnishing an expensive piece of furniture, then you want to maintain its look and feel. In such situations opting for a more expensive varnish isn’t false economy.