Varnish.

Varnish is defined as a transparent material, hard, and protective finish or film primarily used in wood finishes and other finishing. Based on this definition, the varnish has a very broad scope. All finishing materials that produce a transparent layer and protective film are included in the category of varnish. The modern clear coatings such as: Nitrocellulose, Acid curing, PU, Acrylic, Water based can be referred as the varnish, together with film-forming traditional finishing materials such as shellac and oil varnish.

It can be explained easily by looking at the historical of finishing materials development in the past. In earlier times when the technology of finishing materials was still developing, the wood finishing material that could displayed the beauty of wood grain and color were only the oil and wax finish. But the oil and wax were not able to generate a layer of film that can give protection to  the substrate underneath. While the other finishing that could provide better protection was the paint finish. Paint finish might give a better layer finish that can protect the substrate underneath but could not produce a transparent appearance to show the beauty of the natural wood grain and color. Until when people found varnish, a material that is developed from the of oil varnish finish. The varnish is a clear film layer that can make a transparent finish that can show the beauty of the natural base color and the grain of the wood. Since then, every finishing with a transparent film is associated with varnish.

Varnish (oil varnish) is made from oil finish that is cooked and chemically processed with some additional material, resin, solvent and other materials. The mixture composition of the varnish will determine the strength, quality and character of the varnish. A varnish with a large percentage of oil is called as long oil varnish and will produce more elastic and durable film finish. Meanwhile the varnish with little percentage oil is called short oil varnish. This varnish will produce tougher but less elastic film finish. Between the short oil and long oil varnish there is a medium oil varnish the general properties is between both.

Various kinds of varnish.
 
Varnish materials are available in many types and also various grades of quality. The higher grade varnish, the more transparent and more serviceable but usually is also more expensive. Varnish is also available in various types which each has its advantages and disadvantages. But, to do the proper selection we need to know the types of varnish and the basic character of each. 

These are the following types of varnish which mostly used in the wood finishing.

•  Spar varnish.

As the name implies spar varnish was originally meant to be used as materials to coat the wood on the ship. Therefore, the varnish is designed to withstand the hot sunlight, cold nights, and rain in the extreme outdoor weather and even against salt water. Now spar varnish is also widely used to coat furniture or wood products that are used for outdoor purposes. Garden furniture, windows or doors that are exposed to the sunlight and outdoor weather are the items that are suited with this finish.
Spar varnish is a long oil varnish. It will form a film layer that is elastic, durable and high resistant to the outdoor weather but it requires a long drying time.

• Floor varnish.

This is a medium oil varnish. It has a high strength and elasticity, although not as good spar varnish. This material is designed for finishing for the wooden. It is strong enough to withstand the severe abrasion due to the foot and shoes and also a strong enough to hold heavy objects like furniture that are placed thereon. This varnish also resist to the moderate use of cleaning water. This material requires a relatively long drying time, but still less then the spar varnish. Although quite strong, but this varnish will fade after the floor is used for some time, since that a re application of this varnish is often needed.

•  Finishing varnish (furniture varnish)

This varnish refers to the varnish for furniture finishing. This is short oil varnish. It is drying faster and tougher but less elastic. This varnish is hard enough to be rubbed to make a high gloss finish. This varnish is more proper to finish for the indoor furniture. The use of this varnish is mostly in the combination with other finishing material. The finishing process with varnish combine with stains, glaze, shellac and other modern finishing materials are quite commonly found in the furniture finishing industry today.