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The Woodworkers Company

Finishing of joinery

Woodworkers FAQ sheets cover almost anything and everything you need to know about joinery. Please feel free to download and use them to get answers to all the questions you ever had about joinery. If you need further help send us your inquiry using the form on this page.

Finishing of joinery

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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 lustre 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 split 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 transperancies 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 & easy maintenance.
• Can be used internally & externally
• Easy to apply and easily re-applied over time.
• Nourishes the timber & prolongs its life.
• Easily removable from glass
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 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 my 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 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 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. Ask our sales staff for information on preferred primer/sealer products as you may find them difficult to purchase through normal paint outlets.

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 repellent preservatives – Contain repellent 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.

SIKKENS FINISHING PRODUCTS

SIKKENS TRANSPARENT FINISHING SYSTEMS
Woodworkers’ experience with the wide range of coating systems has led us to strongly recommend the SIKKENS range of timber finishing products for our joinery. We believe the range provides the best nourishment for timber, very good durability and minimises hindrance to the smooth operation of joinery.

SIKKENS Recommended Finishing System for Joinery
Exterior
Full sun 1-2 coats HLS then 2-3 coats
Filter 7 or TGL-plus

Note: all exterior finishes must have some pigmentation to provide UV resistance. Sikkens products come in a range of pigments but Woodworkers only stocks the popular colours listed at left. Should a gloss finish be required, use TGL-plus, but remember a gloss finish externally will dull over time.

Interior
2-3 coats Cetol HLS
or
2-3 coats of Cetol TS interior

Preparation and Application
Ensure surfaces are clean and dry. Sand along grain using a fine abrasive paper.
Products are best applied by a long haired brush. Ensure end grain is thoroughly coated (especially top and bottom of doors and windows).
A light sand is likely to be required after the application of HLS particularly on Red Cedar due to the grain raising which is characteristic of the species. Re-apply HLS to any area where sanding has revealed raw timber before applying topcoats.
Solvent based Gupa wood filler can be used as filler/stopper for both interior and exterior use. Nail, holes etc. should be filled with Gupa after the application of the first sealer coat. It can be overcoated with transparent wood finishes.

For further information refer to Sikkens Technical Data Sheets.

Cetol HLS Exterior Seal Coat
	077 Pine
	006 Light Oak
	045 Mahogany
	085 Teak
Can sizes: 1Litre, 5 Litre, 20Litre ( selected colours) Coverage: Smooth, 14 - 18 m²/litre. Rough, 6 - 9 m²/litre

Filter 7 Exterior Satin Finish
	077 Pine
	006 Light Oak
	045 Mahogany
	085 Teak
Can sizes: 1Litre, 5 Litre, 20Litre ( selected colours) Coverage: Smooth, 10 - 16 m²/litre. Rough, 6 - 8 m²/litre

Cetol TS Interior
	For interior use only
	003 Clear
	004 Natural Oak
	006 Light Oak
Can sizes: 1Litre, 2.5 Litre, (003 also in 5 litre) Coverage: 12 m²/litre

Cetol Deck Plus
	078 Natural (honey colour)



Can sizes: 1Litre, 5 Litre, 20 Litre Coverage: 8 m²/litre

Gupa Wood Filler
	We recommend a dark colour filler
	(Teak) for nail holes.
	Available in seven wood colours for
	both interior & exterior use.

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