Timber finishing

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Product finishing information

 

DOES TIMBER HAVE TO BE FINISHED?

YES - All timber joinery has to be finished in some manner to seal and protect it.
By ‘finishing’ we mean the application of either an opaque or transparent finish applied to all 6 sides to protect it from the elements. Without a finish all timber will swell or crack and will discolour. No warranty applies to unfinished joinery.
To preserve your warranty as well as your joinery, a full coat of sealer must be applied to dry timber joinery within 48 hours of delivery. Generally timber joinery will require at least 4 coats of finish, two coats of primer/sealer or undercoat and two top coats to give luster and long-lasting protection. All joinery should be checked regularly, but the life of the finish will depend on its exposure. Joinery fully exposed to weather and sunlight or joinery in coastal areas will need more frequent maintenance. Look for signs of dryness, peeling, surface checking or discolouration.

 

IS CEDAR MORE DIFFICULT TO FINISH THAN OTHER TIMBERS?

YES - Surian Cedar is an excellent timber for joinery because of its durability (class 2), stability, natural termite and borer resistance and its superb colour and grain.It is one of the world’s most beautiful timbers, but it requires special attention to achieve a quality result.Surian is a short grained timber prone to small amounts of tear out during machining and has a natural surface furriness in places. These characteristics can be overcome quite simply during the finishing process provided that the right products and techniques are used.

 

WHAT OTHER TIMBERS ARE AVAILABLE AND HOW DO THEY FINISH?

MAPLE: Woodworkers have an imported range of Pacific Maple doors but do not use it for general fabrication work. Maple is not as durable as other timbers and is suitable for fully painted and protected situations only. It does not have an attractive grain or colour and generally needs to be colour stained or painted rather than clear finished.
ROSEWOOD: Woodworkers fabricates joinery in New Guinea Rosewood but does not carry a stock range in this timber. Rosewood is one of the world’s most stable & durable timbers, but has the disadvantage of large colour variations within each component. For this reason it needs to be lightly stained rather than clear finished.
KWILA/MERBAU: Woodworkers uses Class 1 hardwoods for its sills on assembled frames, usually in Kwila or Merbau. These sills can leach a dark stain onto their surrounds unless they are fully sealed on all sides to contain their natural tannins. It is essential that the underside and all faces of sills are fully sealed with compatible product to that used on the joinery before installation.

 

WHAT TRANPARENT FINISHES ARE RECOMMENDED?

Woodworkers recommend certain products in the Sikkens range of finishes as being ideal for joinery. Please avoid water based acrylic finishes as they void your warranty. Sikkens is an oil based resin that has the advantages of

• Long life in exposed conditions & easily maintained.
• Easy to apply and easily re-applied over time.
• Easily removable from glass
• Can be used internally & externally
• Nourishes the timber & prolongs its life.

There are 2 products in the coating system – SIKKENS CETOL HLS (sealer) and SIKKENS FILTER 7 (top coat) available in a range of tints as well as the honey clear 077 transparent finish.

 

HOW DO I GET A SHOWROOM FINISH ON MY JOINERY?

Apply the first coat of Sikkens HLS within 48 hours over clean raw timber. After applying the initial coat, when dry, lightly sand along the grain of the timber using a fine (preferably sponge backed) abrasive pad or sandpaper. Do not fill nail holes etc until after the first coat is applied as unsightly smear marks will be trapped under the finish and will not be able to be removed easily. Stop holes after the first coat of sealer with an oil based wood fill putty that is darker than the timber (Walnut generally has the colour of a timber knot, whereas commercially available Cedar putties are generally lighter than the timber and do not blend in successfully).
Repeat the sealing and sanding process until a smooth even finish is achieved.
It is important that all smoothing and preparation be done at the priming/sealing stage as you should not need to sand the top coats. SIKKENS FILTER 7 (with UV filters for added protection) is recommended for the top coats as it builds quickly to a rich satin finish.

 

WHAT IF I PAINT THE JOINERY WHITE OR WITH A COLOUR?

We recommend only an oil based enamel finish for joinery NOT acrylic coatings (water based). There is a great deal of difference in oil based coatings available and not all products will give you the finish that you want. Most oil finishes are formulated for weatherboards and external timber and contain very high oil levels which dry slowly and are very difficult to sand. Because joinery requires numerous coats with sanding in between the initial coats, the primer/sealer needs to be a fast drying oil paint able to sand to a fine powder. Top coats of enamel should only be applied when the base coats have been sanded smooth as you should not sand top coats for a professional finish. Avoid all dark colours for external joinery as it will attract and retain heat and can cause the joinery to warp or shrink.

 

WHAT IF MY PAINTER WANTS TO USE DIFFERENT PRODUCTS?

Some painters prefer quick application coatings that give them a very profitable turn around but can be disastrous for the joinery and its owner. Generally speaking, if the joinery is completely internal you can use any finish, but for external items the following is a list of products you should avoid -

• Polyurethane coatings, estapols and lacquers - All such finishes are too inflexible and restrain natural timber movement. They therefore crack quickly and because they retain and concentrate heat, can cause severe warping or splitting in the joinery. They also break down quickly in ultraviolet light. These finishes void your joinery warranty if used externally.
• Acrylic coatings – Have the effect of wrapping your joinery ‘in plastic’ so that it cannot breathe. Coatings tend to ‘stick’ and restrict movement where, for example, sashes have to slide across each other in windows and doors. They are generally complicated to re-apply over time requiring etching and other surface keying to permit subsequent coats to bond. These finishes void your joinery warranty if used externally.
• Varnishes and Natural oil finishes – Marine varnishes do not have a long life & most modern varieties have similar disadvantages to lacquers. Natural oil finishes are good for the timber but tend to be absorbed over a fairly short time so that regular recoating is required.
• Water repellant preservatives – Contain repellant waxes, resins and usually fungicide to provide a temporary water barrier which breaks down progressively due to atmospheric oxidization. Can cause compatibility and bonding problems with subsequent finishes and voids the joinery warranty.