Wood Varnishes

About Wood Varnishes

Stains and treatments are necessary elements for making the most out of wooden floors, decks, furniture and more. They enhance the material’s properties while providing surface protection from elements and the signs of heavy use.

Wood varnish is a clear, transparent timber finish typically composed of drying oils, gums, and an activating agent such as thinner or solvent. It comes in a variety of formulas that can be based on anything from polyurethane and acrylic to alkyd and resins. This type of product is typically associated with wood; however, certain formulas can also be utilised as metal finishes. 

Unlike timber stains, most varnishes appear colourless, while some varieties may contain tiny amounts of yellow or orange. The surface finish is moderately to very glossy and ideal for furniture and floors.

Key Ingredients 

• Oils: The main component of a varnish formula creates a layer that will harden when dried, resulting in a reliable protective coating. The choice of oil determines the final appearance of the wood, its colour, and finishing gloss. 
• Resin: This supporting ingredient adds strength and body to the finished layer. Many compounds, such as tree resins, have a natural origin. Resins can be obtained from insect secretions and organic polymers, but also from plastics. 

The choice of resin and its proportion to oils define the character of the finish, from hard and brittle to flexible and weather-resistant types. Also, the resin content can affect the type of finish, from satin to high gloss. 

• Thinner:  Oils and resins need a solvent to help the application of the finished product. The thinner can be anything from turps to white spirits and even water, and its role is to evaporate their liquid content so that the coating layer can cure and harden. Its proportion to other ingredients determines how liquid the final product will be. 

Types of Wood Sealers

Acrylic

Quick-drying and non-toxic, these water-based compounds feature good UV resistance, making them suitable for both indoor and outdoor use. Acrylic finishes are clear, transparent, and suitable for use with materials other than wood - some formulas can even double as metal finishes. Their penetration power is lower than oil-based varnishes, and sometimes they do not spread as uniformly as other varieties. Acrylics provide gloss, satin, and matte finishes.

Exterior Finishes

These finishes are specially formulated for outdoor use, typically featuring added UV protection along with a fungicide for mould growth prevention. Most varieties allow the wood to breathe, being relatively flexible but slow to dry. 

Polyurethane Varnish 

Distinguished by the exceptionally hard surface they provide, these formulas are often used for floors exposed to heavy traffic. They provide heat, water, and chemical resistance and prevent early signs of wear and tear. The finish is clear and robust, available in gloss, matte, and satin. Polyurethane products do not penetrate below the surface of the wood and typically need a primer such as oil-based varnish.  

Yacht Varnishes

Initially designed for boats in order to protect their structure from the water, these products are remarkably flexible, with a high, oil-based gloss finish based on tung oil and phenolic resins. They are ideal for vertical surfaces and other places not made for walking. 

Alkyd Varnishes 

This category comprises all kinds of wood sealers based on alkyds - modified vegetable and natural oils.

Shellac, Lacquer, & Drying Oils

• These varieties are not strictly varnishes. 
• Shellac is mostly used as a primer for polyurethane and acrylic formulas. 
• Drying oils are components treated to polymerise in order to shorten the drying period.  
• Lacquer is a term commonly used to describe the applying process, where the finish is sprayed rather than spread by brush. 

Drying Process

• Quick Hardening: Some varnishes harden faster than others, depending on the composition and the time needed for the solvent to evaporate. Fast drying can take up to several hours.
• Gradual Hardening: Long-drying formulas require a lasting reaction between resins and oils even after the solvent has evaporated. Once exposed to the air, they pass through oxidation and polymerisation processes, taking up to several days to achieve the proper hardness. 

Things to Consider Before Choosing Varnish

Interior-only formulas should not be used outdoors. The absence of adequate resistance to UV rays and elements will likely cause the wood to deteriorate sooner than it would with suitable products. 

Using lacquer spray is generally more accessible. Brushing requires some practice and skills to result in an even, professional layer of timber coating.

More viscous varnishes can also be more challenging to apply and take longer to dry. At the same time, they allow for more even applications.

If you need assistance to find the right wood varnishes for your home or office, ArchiPro provides a connection to the various professionals, ready to assist with all requirements and questions. Simply click "Contact supplier" on the product's page, or visit the supplier's website directly from the product's page.