When it comes to wood, varnishing is a key step in maintaining and improving its natural beauty. Whether you are refinishing some wooden furniture or carrying out a DIY project, varnish creates a protective finish that protects the wood from minor damages, Ultra Violet Light (UV) and, most importantly, the weather.
Using varnish on wood is very important in order for it to last long and look good. Today, we are going to discuss the many advantages of wood varnishes, speak about varnish types and ways of application, tell you how not to screw up while varnishing a wooden surface, and more.
First Off, Why Varnish Your Wood?
Wood is naturally beautiful but incredibly susceptible to water, UV Light and staining from wear. The protective barrier provided by using varnish keeps these factors at bay, which is why varnish is a must! The process not only adds years to the life of the wood but also makes it look better. Varnish supplies a shine or matte-like finish and actually shows the timber grain better.
Varnish can also keep the wood from dehydrating and cracking, which can be crucial for furniture set up outdoors and left in various changing climatic conditions. It is also critical for boats, ensuring they are protected against the elements. Using varnish on wood and your wooden surfaces means keeping them in top-notch condition for years to come.
What Are The Types Of Varnish For Wood?
It is important that you choose the appropriate varnish that will give you optimal results for your project. Varnish comes in different types, each offering its own levels of protection and finish.
Spar varnishes are traditional varnishes made from natural oils. These are often sold as Yacht varnishes, and whilst expensive offer beautiful and durable results.
Polyurethane varnish is cheaper and more readily available than spar varnishes. For ultimate durability consider two part polyurethane varnishes that will have to be mixed prior to use.
Acrylic varnish is a water-based varnish. Brush cleaning is easier, but durability is restricted. The solution may be suitable for projects that are on a short deadline and do not want any odour during application.
By selecting the right varnish for your wood, you can strike a perfect harmony between looks and strength.
How To Apply Varnish On Wood?
Using varnish on wood and wooden furniture takes a bit of preparation and technique to achieve a professional finish. To start off, you must prep the wood surface properly.
Preparing the Wood: First, use a sander on the wood to make it smooth and even. With sanding, all imperfections are lifted away and the pores of wood are opened so that it can stick to the varnish properly. After sanding, clean the surface well to remove all the dust and debris.
Priming the wood for Varnish: The most important step in getting a long lasting varnish finish, and often done completely wrong.
Most varnishes will suggest thinning the varnish with a solvent, and using that as a primer. Most varnish finishes however will fail, completely, within a very few years. We have all seen the damage, it starts with little spots, they grow to become bigger circular bubbles in the varnish. Soon you are back with the sander taking the wood back to bare and starting again.
Prime your wood with Smiths Clear Penetrating Epoxy Sealer (CPES) first. Use two coats or until the CPES leaves a glossy finish on the surface. This will penetrate deeper into the wood than thinned varnish, enhancing the grain and giving a truly stable base for the varnish to adhere to. It’s far faster and easier to apply than thinned varnish too. Furthermore it is almost impossible to mess up as it doesn’t run like varnish.
The first coat of varnish, whether spar or polyurethane, should be applied once the solvents have fully dissipated from the CPES, but before the CPES has fully chemically cured. 24 hours is normally a good indicator, but often this step can be done far sooner. As the CPES will not have chemically cured by this stage it will form chemical bonds to any varnish. As the Clear Penetrating Epoxy Sealer is designed to bond firmly to the fibres in the wood the varnish will be firmly glued to the timber itself. That is how you can achieve a varnish finish that can last 20 years or more with proper maintenance.
Applying the Varnish: For even varnishing, use a good-quality brush or foam applicator.
Varnish needs to be thoroughly stirred prior to application as it can separate, then it should be applied in long, smooth strokes running with the grain of the wood. Make sure your brush isn’t dripping with varnish because then you’ll end up (quite literally) with drips everywhere and an uneven finish.
There are many types of varnish available, and there are differences in application techniques too. The most important rule with the initial application of varnish is to use enough of it. Varnish contains Ultra Violet Light (UV) blockers. UV Light destroys wood, it is what turns the surface of wood from coloured to the silvery grey that you see with aged exterior timbers. That look is caused by the destruction of the lignin in the wood leaving just the bare cellulose fibres. These reflect light readily, so you see a silvery surface which darkens when wet as the light now penetrates better.
We always recommend using half a litre of varnish per square metre of exterior timber. We do not describe a number of coats, because different people and different varnishes give different thicknesses of varnish per coat. Work out the area of your timber, calculate the right amount of varnish, and add coats until you have used that amount.
For example: My door is 203cm high and 92cm wide, with a window of 45 * 55 cm in it. That is 1.87 – .25 = 1.62 square metres. I need to apply 0.8 Litre of varnish to the outside of that door. The inside I can choose to just protect with CPES alone, as it will not get sunlight falling on it.
Maintaining Varnished Wood
The key to a long lasting varnish finish is maintenance. The UV light blockers in varnish degrade with exposure to UV light. That means you have to add maintenance coats to your varnished finish, or the UV light will get to the wood. When the UV gets to the wood, it destroys the wood that your varnish is stuck to. Enter the world of spots appearing under your varnish – and you have to sand back to bare wood and start again.
So, depending on your climate, and the amount of sunlight that your wood is exposed to, you will need to work out a maintenance regime.
For example, a South facing door, in full Southern UK (Kent) sunlight, might need two maintenance coats every 2 years. You will have to clean and key by sanding the surface prior to the first coat. For the second coat please follow the varnish manufacturers re-coating instructions and schedule.
Top Mistakes To Be Avoided While Applying Varnish On Exterior Wood
Using varnish on wood seems easy, but the smallest mistake can make a big difference in the final appearance or longevity.
Priming properly. The most important step in obtaining a durable varnish finish. Use CPES and get a finish that lasts.
Apply enough Varnish to protect. Use enough varnish to keep the UV light off your timber. If you do your finish will last, if you don’t, the UV light will destroy the fibres your varnish was stuck to!
Maintain your finish. The UV blockers in varnish are themselves degraded by UV light. You have to apply maintenance coats of varnish to ensure your wood stays protected from the UV light in sunlight.
Proper surface preparation of the wood. If you skip the sanding and cleaning, then your wood could end up containing minor holes or bumps in the paint. It is also important to remember that varnish should be applied in thin layers and not over brushed, or bubbles and streaks may develop on the surface.
You need to take your time and let the varnish dry for the instructed amount of time from the manufacturer between coats. It is also worth mentioning that by applying the incorrect varnish to your project, you could see an end result that is you not getting the finish that you had hoped.
Make Wood Good For All Your Varnish Needs!
Here at Make Wood Good, we appreciate the natural beauty of wood. Our line of wood care products, like our Rotten Wood Repair Kit, is meant for high-quality wood restoration and protection. From the at-home DIY person to the enduring professional woodworker, we guarantee our high-quality finishing products will keep your wood clean and looking top-notch for longer!
These are high-quality finishes that are made to endure exposure to moisture, UV damage, and normal wear. Whether you are applying our varnish products to outdoor furniture or using them for interior surfaces, you can count on a perfect finish every time.
Make Wood Good offers you a product for every wood care requirement. So, if you ever need to look after wood, Make Wood Good has the solution.
Get in touch with us now to discover our full line of wood care goods and see how we could assist you with your woodworking!