So your board is ready for it's finishing coat, great! This can be either paint or varnish. The choice is yours but I prefer varnish as any imperfections from the build process are less visible and it is lighter than paint.
Finishing the board with varnish not only preserves it, but it also helps protect it against scratches and stains. I always use proper Marine Varnish as it is designed for the rigors of outdoor exposure and has excellent UV resistance.
Below are the steps I use to varnish my boards and they always turn out great.
- Work in a well ventilated area away from any wind or moisture.
- Clean your work area thoroughly, it's not going too far to vacuum and mop the floor to remove all specks of dust! Clean the board by wiping it down with a damp cloth then letting it dry.
- Pay attention to the temperature and humidity. The temperature in the area you will be varnishing should be between 70 °F and 80°F (about 21°C to 26°C).
- Don your protective equipment, a ventilated face mask and protective eyewear.
Thin the varnish with the appropriate thinner for the first coat, I use a 5:1 ratio of varnish to thinner.
Use a 100m wide (4inch) foam brush and apply around 20cm at a time brushing across the board first then tipping the foam brush back the the bow to smooth out the finish.
Maintain a wet edge and never got back to touch up any errors.
Leave to dry - allow this first coat to dry at least 24hrs before flipping over the board and varnishing the otherside.
Take the board outside your work area and sand it with 240 grit sandpaper removing any high spots and working to an even dull finish all over.
Thoroughly clean the board.
- Apply a further 2-3 coats of un-thinned varnish to get your desired level of gloss, sanding with 320 grit sandpaper and cleaning the board in between.