To varnish already varnished wood, you typically need to clean and prepare the existing surface to ensure the new varnish adheres properly before applying the new coats.
Revarnishing a piece of wood is an excellent way to refresh its appearance and provide continued protection without necessarily stripping it back to bare wood, provided the existing finish is in good condition. The key is to prepare the surface adequately.
Here’s a straightforward approach:
Preparing the Surface
Before applying any new varnish, the existing finish must be clean and slightly roughened to create a good bonding surface.
- Clean Thoroughly: Start by cleaning the wood surface to remove any dirt, grease, or grime. A mild detergent solution or a dedicated wood cleaner can be used. Rinse thoroughly and allow the surface to dry completely.
- Inspect the Existing Finish: Check for any peeling, chipping, or significant damage. If the existing varnish is extensively damaged, you might need to consider stripping it entirely rather than simply applying a new coat on top. For minor scratches or wear, light sanding is usually sufficient.
Sanding for Adhesion
This is a crucial step highlighted in the process.
- Light Sanding: Next, use a 220-grit sandpaper to sand down the existing varnish. This step is not about removing all the old varnish, but rather to roughen up the surface. Roughening the surface creates 'tooth' for the new varnish to grip onto, ensure maximum adhesion for the new varnish. Sand with the grain of the wood for a smoother finish.
- Clean Dust: After sanding, it's essential to remove all the resulting dust. Vacuum up the dust resulting from the sanding. You can also use a tack cloth or a slightly damp cloth (ensure the wood dries completely before varnishing) to remove any remaining fine particles.
Applying the New Varnish
With the surface prepped and clean, you can now apply the new varnish.
- Choose Your Varnish: Select a high-quality varnish compatible with the existing finish (most modern varnishes are versatile, but check product labels). The reference specifically mentions using high-quality floor varnish, which is durable.
- Apply Thin Coats: Now that the surface is ready, apply two coats of high-quality floor varnish. Applying multiple thin coats is better than one thick coat, as it allows for better drying and a more durable finish. Use a good quality brush, roller, or sprayer suitable for varnish application.
- Allow Drying Time: Follow the manufacturer's instructions for drying time between coats. Sand lightly with very fine sandpaper (e.g., 320-grit or higher) between coats if recommended by the product instructions, and clean off the dust before applying the next coat.
- Final Coat: Apply the final coat smoothly and allow it to cure fully according to the product directions before using the piece.
By following these steps, you can successfully apply new varnish over an existing coat, refreshing the wood's appearance and extending its protection.
