Timber iQ April - May 2018 // Issue: 37 | Page 47

FEATURES “Factors such as changing air moisture and rain may cause the wood to expand and contract,” says Lawson. He advises that wood should be regularly maintained to expand its lifespan by applying maintenance coats. “Some coatings (such as varnishes) need re-coating after a year or two and some coatings (penetrating oils and wax sealers) need re-coating twice a year.” THE FINISH It is often said that to enjoy the material longer, preparation plays a huge contributing factor. There are many products on the market that clients and contractors can choose. You are indeed spoilt for choice. With a good oil, wax or sealer and proper maintenance you can never go wrong. TOOLS FOR THE JOB 1. Sandpaper in various grades, from course to fine grit 2. Paint stripper 3. A scraper 4. Something to neutralise the paint stripper after use 5. A paint tray 6. Good quality paint brushes in various sizes (widths) 7. Mineral turpentine to wipe the wood after sanding (and to clean the brushes, if working with a turpentine-based sealer / varnish) 8. Rubber gloves to protect your hands 9. A painter’s apron or overalls 10. Old newspaper to place under the item being worked on, to make cleaning up a bit easier 11. A sturdy ladder, if necessary Source: Woodoc TIMBER TREATMENTS Varnish A product that merely sits on the surface of the wood, achieving minimal penetration. The old practice of diluting the first coat of a varnish to achieve ‘penetration’ does not work. The particle size of the varnish remains the same after dilution and only the solvent will penetrate the wood. Hence, varnish is a pure surface coating. When varnish is subject to weathering or damage, it will delaminate and ‘bubble’, peel or flake off wood. To re-coat the old surface, the coating must be completely removed. Oils / waxes Product does not form a surface coating to protect wood against mechanical damage / weather but penetrates the wood. It is excellent for stabilising wood in the short to medium term but offers no real protection to the wood surface. Thus, it must be re-applied regularly but generally no stripping or sanding is required before re-application. Sealers A sealer combines the best characteristics of a varnish and an oil by penetrating wood to stabilise the wood and then builds up on the surface to offer surface protection and finish. Woodoc sealers all fall into this category. It is not necessary to strip or sand a Woodoc sealer off the wood before applying a new coat. In exterior conditions the surface will need a clean with a stiff brush (or fine steel wool) and turpentine to get rid of any pollution before application. In indoor conditions, a light sanding on and around the area to be repaired followed by a wipe-down with mineral turpentine is all that is required before application. Source: Woodoc // APRIL / MAY 2018 45