Wood has lots of little ‘pores’. This can result in a build up of dirt on the surface which, in turn, makes unfinished wood the perfect place for bacteria to thrive. This can be because the wood wasn’t painted properly in the first place, the wrong paint was used or the moisture is coming from a hidden source, such as a leak. Try and identify the cause — it could be condensation seeping in through an area that needs caulking. Once identified and sorted, repaint. Can you paint plywood? So, now you know more about applying varnish over painted wooden pieces. You learned that it is basically possible to varnish previously painted wood. Also, you figured out how varnish works on wooden surfaces. Moreover, we told you how exactly varnish should be applied so that you can achieve a smooth and even coating.

Alternative to the Everbuild gloss: Rustins EAVG250 250ml Outdoor Varnish Gloss– Rustins is the name in varnish and very trustable. If your wooden item is painted with an oil-based paint (like on most of older painted surfaces), note that varnish will not adhere properly to it without adding a primer first. If you are still not sure what kind of paint was used, test it by rubbing a small area with a cotton swab dipped in alcohol. Sand the paint finish with fine-grit sandpaper (220-grit) before applying varnish. Sanding will remove imperfections and bumps, and make the paint ready for sealing. However, to make wood practical for everyday use in our homes, it is necessary to apply a finish, such as varnish. What does varnish do? Ideally a spray application of a number of thin coats will be best, however I appreciate that this is not perhaps a viable option and brush application will be fine, with a sand between coats with a 240 grit paper. Wipe off the sanding dust and apply further coats until you have the desired finish. I would expect 3- 4 coats for you project, however two will be a sufficient minimum.If the surface or area you are painting is prone to wear and tear, we would advise that you think twice before using an emulsion. This is because you’ll find that it marks too easily and you’ll have to frequently touch up the damaged areas. For high traffic wooden surfaces, we would recommend either a satinwood or gloss paint. Conclusion This should mean that the wood will last for much longer (and look much better), than if no varnish or finish had been applied. Resin: This is the component that adds the strength and body to the finished varnish. There is a huge range of compounds from natural products such as tree resins and even insect secretions to organic chemicals such as polymers and plastics that are used as varnish resins. Like the oil the choice of resin can affect the varnish so resins that do not colour the varnish are favoured. The way that they react or act with the oil will have a bearing on the properties of the varnish Sand the wood before painting. Sanding the wood helps to smooth out any rough spots and provide a better surface for the paint to adhere to.

Thinner (or Solvent): This is the ingredient that thins the oils and resins to allow the varnish to be applied easily. Having done its job it should evaporate and allow the resin and oils to cure and harden. The thinner can be a range of solvents, such as turps or white spirit. Water can be used in some varnishes

Clean the paint finish to remove dust, dirt, and debris that can show once the varnish dries. Since most varnish types have a transparent finish, they won’t hide imperfections on a surface. What you should do is to wash the surface of your wooden piece with a soapy sponge and allow it to dry. Also, remember to sand the painted surface lightly with 100-grit sandpaper. It will help you rough it up to make the varnish adhere better. Yes is the simple answer. However, plywood comes in different grades so some need more preparation than others. If you have the finest grade there’s very little prep needed so you can start painting plywood almost straight away. Varnish can be applied with a brush, which is more typical, or a roller. If you are planning to use a roller use one with a short pile. See here for help on choosing a roller. Apply with the grain to get a smooth and even finish. A low-gloss or satin finish is more suitable for retaining the older look of the paint, or for more of an antique finish. Apply the Varnish