What is Varnish?
The Varnish is a transparent, hard, protective finish or film primarily used in wood finishing and also for other materials. The different Types of Varnish are traditionally a combination of drying oil, a resin, and a thinner solvent.
The varnish is a finish and protecting film that is typically associated with wood but can be used on other substances also. While having many applications as paint like protection and aesthetics, the varnish will penetrate the wood as well as forming a protective film over the surface.
It enhances and gives comfort to the grain of the wood and is resistant to impact, heat, erosion, water, and alcohol. It can be used as a top coat over a painted surface.
The varnish is a solution of resin in either oil, turpentine, or alcohol. It dries after applying on the surface of wood, leaving a hard, transparent and glossy film of resin over the varnished surface.
- Different types of varnish finishes are generally used to get glossy surfaces on materials but also designed to produce semi-glossy surfaces by the addition of ‘Flatting’ agents. Water-based acrylic types of varnishes are becoming more popular for their environmental and health benefits.
- The varnish is applied to the,
- Painted surface to increase its brilliance and to protect it from the atmospheric action.
- Unpainted wooden surface to brighten the ornamental appearance of the grains of wood.
Why Varnish is Applied Wood?
Due to following some properties varnish is important to wood to increase the life period of wood:
- Varnish protects wood from shrinking, expansion, abrasion, and fiber erosion of wood and the detrimental effects of living organisms such as fungi, bacteria, and bugs make it necessary to protect the wood.
- The properties of the varnish which give resistance to external factors, bring color to the wood and highlight its pores, brings an aesthetical look to the wood in terms of protecting the wood and prolonging its life.
- Varnish protects the painted surface from atmospheric elements and makes the surface easier to clean.
- Varnish creates an even sheen over the entire surface of the painting. A double layer of varnish will even out the final appearance of the painting, giving it a consistent overall look.
- Dust can be accumulating on the surface of paintings over time, especially if a painting hangs in a smoky environment, thus a protective layer of varnish can be used to restore the painting to its original look.
Different Types of Varnish
There is a huge range of different types of varnishes. Here the most common types of varnish are listed below,
- Spirit Varnish
- Acrylic Varnish
- Exterior Varnish
- Polyurethane Varnish
- Yacht Varnish
- Oil Varnish
Lets discuss each types of varnish in details with their uses.
1. Spirit Varnish
- It is the types of varnishes in which spirit is used as a solvent is known as spirited varnish or French-Polish.
- Shellac is dissolved in spirit and the product is applied in a thin layer.
- Spirit types of varnish give a translucent finish thus showing the grains of the timber.
- These, however, do not weather well and as such are used for polishing woodwork not exposed to the weather.
2. Acrylic Varnish
- These types of varnishes are quick-drying and non-toxic water-based varnishes which generally have good resistance against ultra-violate rays, thus they can be used inside as well as outside surfaces exposed to sunlight.
- They can be used on other materials other than wood, so they are more versatile than other varnishes. They are clear, highly transparent, and do not tend to penetrate the wood like other types of vanishes.
- Being water-based you can clean up it with water, which makes them very user friendly, but sometimes does not spread as uniformly as other varnishes.
- They are mostly available in sheen, satin and matt finishes.
3. Exterior Varnish
- As the name indicates, types of varnishes that have been specially formulated for use of outside surfaces exposed to the weather.
- They have added ultra-violate ray protection so that the wood beneath the layer of varnish is protected.
- They are often microporous which allows the wood to breathe and have an added fungicide to prevent the growth of fungi and termite.
- They are likely to be very comparable in formulation and performance to a yacht varnish, being relatively flexible, but slow to cure even if they are touch dry relatively quickly.
4. Polyurethane Varnish
- These types of varnishes give a really hard surface and are often used for floors and areas which are going to get a lot of wear and tear. They are also heat resistant and will give a clear and tough finish, which is available in gloss, satin and matt finishes.
- Polyurethane types of varnishes does not tend to penetrate the wood so they are often primed with an oil-based varnish or a thin shellac solution. Do not try and put an oil-based varnish on top of a polyurethane varnish as it will not bond.
- In addition to the excellent hardness and durability, they are resistant to spills of mild acids, solvent, and other chemicals.
- They are not resistant to UV (sun) light, so if used outside then try to find one with added UV protection or it will deteriorate quickly.
5. Yacht Varnish
- It is also called marine varnish, as this is a varnish that was originally designed for use on boats where the primary purpose was to ensure that water did not penetrate the wood.
- To achieve this the varnish had to be highly flexible. A rigid, inflexible varnish might crack as the wood bent and flex under the strain of the sea and these cracks could allow water to penetrate.
- Usually, these did not have much gloss, as appearance was a secondary feature, and little UV protection, but now most yacht varnishes have a high gloss finish based on tung oil and phenolic resins.
- They are ideal for use on outside timber, but not for a surface that is going to be walked on.
6. Oil Varnish
- These types of varnishes are made by dissolving hard resins like amber or copal in oil.
- They are slow to dry but are the hardest and most durable of all varnishes.
- They are suited for being used on exposed surfaces requiring polishing or frequent cleaning and for superior works.
How to Apply a Varnish?
Followings are tips to get great finish after applying varnish:
- Before starting to apply varnish on the surface of any material, ensure that the surface is well prepared; varnish accentuates rather than hides marks, unwanted stains, and bumps.
- The varnish is also its primer and undercoat, although in some cases it is better to apply the first thin coat with roughly 10% white spirit and water for water-based varnishes. This is particularly true if we using a polyurethane varnish.
- Once the first coat has been applied and it has dried, then it has to be rubbed down lightly and a second coat is then applied.
- Dust and varnish don’t mix, because all the sanding before applying the varnish will inevitably create a lot of dust. Give it time to settle and get rid of as much as possible.
- If you apply varnish in a dusty environment, it will stick in the drying varnish and potentially ruining the finish. If this problem occurs, then you will have to sand it down gently with a fine-grit paper and then apply another coat.
- Unlike paint, varnishes and stains are intended to soak into the wood. You can also apply a clear varnish to the stain to improve the finish, enhance the look, and also make it more durable.
- Different types of varnishes can be applied with a brush, which is more usual. If you are applying varnish using a roller, use one with a short pile.
- The first coat of varnish applied should be parallel to grains of wood and another coat should be perpendicular to grains of wood to get a smooth surface and which makes varnished material more durable to weathering actions.
Advantages of Varnish
Followings are advantages of different types of varnishes,
- The varnish is applied to unpainted furniture and other woodwork to decorate the surface without hiding the beautiful grain of the wood.
- To protect the surface of wood against the adverse influence of the atmosphere.
- Provides radiant beauty to the wood.
- Helps in protecting the wood by binding the surface.
- It is used to prevent hairline cracks and absorb the effects of scratching and external damage.
- It helps in reducing the transfer of moisture between the wood and the surrounding weather.
- It provides softness and long-lasting flexibility to the material.
- The varnish is resistant to UV rays and doesn’t turn yellow.
- It brings out the natural grain of the wood.
- It is inexpensive to purchase.
- Painted surfaces are varnished to enhances the appearance of the paint and increase the durability of the paint film.
Disadvantages of Varnish
Followings are disadvantages of different types of varnishes,
- Varnish has a strong and unpleasant odor so it is requiring to wear a mask while using varnish.
- Varnish has low resistance to abrasion.
- It has a possibility of reaction with glues, waxes, and silicones.
- The varnish is harder to apply in the summer.
Watch Video: How To Apply Varnish On Wood
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