Learn the basics of when and how to use these finishes and you will be well on your way to success in woodworking’s crucial final stage.
Possibly the most underrated and underused finish, shellac is fairly easy to apply (pad, brush or spray), dries very quickly, is very clear, resists moisture transfer, and can be rubbed out nicely. It doesn’t stand up to heat, water, or chemicals very well though. It’s a great finish for a piece of furniture that will not be subject to heavy wear, like a display cabinet or jewellery box. Shellac also makes a great washcoat/barrier coat when refinishing. For more information, see the finishing article in our April/May 2011 issue.
Available in oil- and water-based versions, as well as gloss, semi-gloss and satin, polyurethane is a film-forming finish that offers lots of protection against scratches, water and chemicals. It’s usually brushed or sprayed on, then left to dry; oil-based polyurethane takes much longer to dry than water-based polyurethane.
Very easy to apply, tung oil is similar to linseed oil. Coats are wiped on the wood and left to dry. If half a dozen coats are built up, tung oil is quite water-resistant, although it offers little protection from scratches and moisture transfer.
Oil-based polyurethane and a mixture of penetrating oils are combined to create a finish that is easy to apply, offers decent protection, and feels good when cured. Store-bought mixtures are often sold as “Danish Oil”. Check out the finishing article in our April/May 2011 issue for details on mixing your own oil/varnish finish.
Most commonly available in oil- and water-based versions, pigment stains leave pigment in depressions (pores, scratches, etc.) in the wood. Surface preparation is important when using pigment stains, as the pigments will highlight random orbital sanding scratches and other imperfections.
Available in oil, alcohol and NRG versions, but for small-shop use, water-soluble is the most common. All types except NGR are sold in powdered form, and is mixed shortly before it’s used. Its biggest pro is that it will not obscure the wood, like most other stains. Aniline dye stains the wood fibres fairly evenly, unlike pigment stain, which deposits pigment mainly into the pores of the wood. It’s available in many different colours.
Colours wood by sitting on top of it, rather than penetrating into it, making it great for colouring blotchy woods like pine, maple and cherry. It’s easy to wipe on and comes in many colours.
Though it’s usually sprayed, brushing lacquer is also available. Lacquer is fast-curing, rubs out well and has good clarity. The main downside is its harsh solvents. Depending on the exact type of lacquer used, this film finish has decent wear, heat, water, and water vapour transfer properties. I would recommend spraying lacquer if you have spray equipment and a booth.
If you are after some opaque colour for your next project, reach for milk paint. It’s safe, easy to use and can be brushed on in many colours. Milk paint dries chalky, and can easily be sanded off corners and surfaces to bring a distressed look to furniture. To protect dried milk paint you can apply a wiping oil like tung or hemp oil.
Rarely used as a finish on its own (though it can be), wax is usually applied on top of a fully cured finish with #0000 steel wool, to smooth the surface and change the level of sheen, or with a clean cloth to add a bit of protection. Wax reduces abrasion and protects against stains and liquid spills.
Rob is a studio furniture maker and the editor at Canadian Woodworking & Home Improvement.
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