How to Varnish Outdoors

Preparing Your Working Space & Equipment

Having a brightly lit work area, will make it easier for you to find imperfections in the wood and your varnished surface. Good ventilation is a must as varnish and solvent fumes can be harmful to inhale. Make sure the area is clean and free of dirt and dust. Vacuum or mop the area to protect your work. Try not to work on windy days as dust particles can land on your newly varnished surface. If the area temperature is too hot, the varnish will dry too quickly and if it is too cold, the varnish will dry too slowly. Ideally, temperatures should be around 21°C to 26°C. Wear proper protective gear (protective gloves, protective glasses and a ventilation mask). Clothing that you don’t mind getting dirty or stained would also be advisable.

Choosing the Right Varnish

Oil-based varnishes, such as TintEX Marine Varnish, are very durable. They usually have to be mixed with a TintEX Thinner.

Acrylic, water-based varnishes have low-odour and can be mixed with just water, such as TintEX Water-based Varnish.

Preparing the Surface

1. To clean or not to clean: You can either apply varnish over an already-painted surface to preserve it, or apply it to a raw, unpainted surface. Alternatively, there are various ways to remove old finishes including using a paint stripper and sandpaper.
2. For raw surfaces: If your wood has never been painted or varnished, or if you wish to preserve the original paint, you can proceed to Step 5.
3. Use a paint stripper: Removing old finishes with paint stripper, can be done by applying the stripping solution to the wood, using a paint brush. Leave the solution on the wood for the required amount of time stated on the packaging, then scrape it off using a putty knife with round corners. The stripping solution must not be left to dry. Make sure to remove all the stripping solution residue before progressing further.
4. Sanding to remove paint: When removing old finishes, sanding can be done with a sanding block or hand held sanders for flat surfaces, but for uneven surfaces, sandpaper it the best solution. Start with medium grit (150) and move up to a finer grit (180).
5. Smoother finishes: Sand the surface with a fine grit sandpaper (220). This will ensure a smooth surface that will be just rough enough to hold the varnish.
6. Cleaning: Clean the wood surface with a damp cloth so that all dust and dirt are removed and leave to dry. Make sure your work area is clean, too.
7. Using a wood filler: You may need to fill some wood grain with a matching filler product.

Varnishing Your Wood

1. The first coat: Thin out your varnish. This will help to seal the wood. The remaining coats will not need to be thinned. Oil-based varnish will need to be thinned using a thinner. Use 1 part varnish to 1 part thinner. Water-based acrylic varnish can be diluted using water instead. Use 1 part varnish to 1 part water. Apply it with a paint brush or foam applicator using long and even strokes along the grain of the wood and leave to dry for 24 hours.
2. Buff the first coat: Starting with a 280-grit sandpaper, buff the first coat and then wipe with a wet cloth and let dry, then clean the surface and work area with a damp cloth.
3. Apply the next coat: Apply the varnish with a clean brush, a foam applicator or spray gun and leave to dry for 24 hours. Make sure the coat is nice and even. There should be no puddles, drips or runs.
4. Buff the second coat: With a 320-grit sandpaper, buff the second coat and then wipe with a wet cloth and let dry, then clean the surface and work area with a damp cloth.
5. Repeat: Steps 3 and 4 of this section, should be repeated for 2 to 3 more coats. You can use 400-grit sandpaper at this point.
6. For the final coat: It is best to wait 48 hours before varnishing.
7. Let the varnish cure: This will take between 24 hours and 30 days, depending on the varnish.

Now you have a beautifully varnished outdoor surface!