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Ask an Expert

Joinery, cabinetwork & furniture

Like to know what wood to use building a pergola or framing a barn? How about the difference between tung oil and polyurethane as a floor finish? How to revive decking or deal with merbau stains? Or how to meet the building code or bushfire standards? Or ask about the environmental advantages of wood or forest certification?

Q. I wish to create a piece of laminated timber 1500mm high, 3000mm long with a thickness of 25mm which will be affixed to a wall by a timber frame. The laminated piece will be curved and will have holes cut out to accommodate the neck of a wine bottle. It will be veneered. I cannot find a contractor to make the laminated piece at a sensible price. Joiners will do the job but for ridiculous sums. Any ideas?

That's a big chunk of wood and there could be some issues in veneering it if it's curved. We don't have any expertise in costing, and can only suggest you try a company that's familiar with producing laminated timber. Often contractors who are unfamilar with a particular technique will quote high to cover themselves against unknown factors. Dale Glass Industries are glulam specialists and are experienced in making curved benchtops. You can visit their website at

Q. We are trying to gain some technical advice regarding problems we are having with rubberwood. We manufacture cabinets including bathroom vanities out of this timber, and export them all over the world, unfortunately approx 3 percent of the cabinets drawer fronts have been cracking in cold temperature zones. We wanted to get in contact with an expert or consultant that may be able to help us resolve this issue. If you could please get back to me regarding this with any suggestions or contact details of a consultant or expert we would be most grateful.

Our first thought would be to look closely at the moisture content of the rubberwood supplied to you. Rubberwood is a relatively stable timber but, like all timbers, swells and shrinks on gaining or losing moisture. Temperature is not particularly important for wood, except to the extent that it influences moisture change. In a cold climate, indoor relative humidity can be quite low, allowing moisture to evaporate out of wooden items. There is a lot of information on the net on this subject. One answer to a similar question is as follows: "There may be multiple causes [of drying], but a common one is that the relative humidity in our houses is lower in winter. When air is heated the total water content stays the same, so the relative humidity drops, unless your heating system adds additional moisture. Try running a humidifier and see if it reduces the problem." It may be that your supplier is taking advantage of the low shrinkage rate of rubberwood by not being sufficiently careful about kiln drying the timber, or it may be that indoor conditions where the cabinets are located are particularly dry. Do you monitor the moisture content of the rubberwood before using it to manufacture your cabinets? If not, we suggest you obtain a moisture meter and use it for regular quality control checks on incoming timber.

Q. As part of my HSC major work for Design and Technology, I need to purchase some timbers as I am making a chair which will only be used indoors and will be fixed in place. I am looking at the durability classes of timber and was wondering that if the timber is durable (i.e. Class 1/2), is it a harder timber to work with than those less durable timbers. It would be much appreciated if you could help me with this question.

The word "durability" can be a bit confusing - it has a special meaning in the timber industry. When timber publications talk about durability they are referring to resistance to wood rot and insect attack. Some timbers last longer than others when exposed to these hazards, and the Australian system gives commonly used timbers a rating from Class 1 to Class 4. But durability in that sense is not necessarily related to toughness, or resistance to wear and tear. Some of the durable timbers are quite soft, eg. western red cedar. For indoor furniture Victorian ash is quite a good choice as it is reasonably hard wearing but not as difficult to work with as some of the denser Australian hardwoods.

Q. We are wanting to build a front door out of an Australian hardwood. It will cop a lot of afternoon sun and we are in a BAL rating 19 so we are looking at making it 900mm x 2.4m and 45mm thick. It will be rounded/arched at the top too. I can forward through a photo if another email address is supplied. If you know what Australian hardwood would be suitable for this door and could please kindly let us know, that would be much appreciated.

In BAL 19 areas an external door complies if it is solid timber and has a thickness of at least 35mm for the first 400mm above the threshold. We assume that although the door will be exposed to sun it will be sheltered from rain. If so, Victorian ash would be suitable and a joinery shop should be able to make the kind of door you describe. As with any joinery, the timber must be kiln-dried and in this case we recommend a moisture content of not more than 12%.

Q. I am looking for an Australian species that is similar to a white American ash. I am looking to build some furniture with it, and looking for a product similar to this: Can you recommend any locally sourced timbers that might work?

The image you refer to looks as if it has had a white liming stain applied to it. American ash isn't quite as white as that naturally. The golden colour on the end-grain is more typical. Be that as it may, you would find that Victorian ash is similar and makes good quality furniture. We suggest you visit a specialty timber supplier to view some samples, or look at some images of Victorian ash on the net. If you like the white look, write "white liming stain" in your browser for information on products that will achieve this result.

Q. We are planning to build with spotted gum cladding, flooring, cathedral ceiling and decking. Your website says that spotted gum is suitable for windows, but we are having trouble finding a supplier of spotted gum timber windows. They all say that spotted gum would be a poor choice as it is difficult to machine and prone to movement and difficult to obtain in the right size (as it is all turned to flooring, decking or cladding). If this is the case, can you suggest a wood species that would be complementary to spotted gum for this purpose, or otherwise suggest some suppliers in Tasmania or Victoria?

We are inclined to agree that while spotted gum is suitable for any external use from a durability point of view, it's perhaps not an ideal species for window joinery. Kapur or merbau would be more readily available hardwoods which are often used for window joinery in bushfire areas. You will need to find a joinery shop that is familiar with architectural joinery (ie. one-off jobs) rather than one that makes mass-produced standard windows, which are only available in a limited range of species.

Q. I would like to use an Australian Hardwood preferrably spotted gum to clad a 4m diameter circular cafe. Is there a spotted gum veneer product that can be bent to match this curve or are there other Australian hardwood timbers that are suitable for this application?

Very thin plywoods are available (down to 0.4mm) but with a 4m diameter you will be able to bend plywood or veneered MDF that is thicker than that. For example the Laminex Group advise that their Craftwood® (Thin) MDF can be bent to produce curves for furniture, doorways and other applications to a minimum radius of 50 times the panel thickness. Therefore 3mm MDF could be bent to a radius of 150mm or a diameter of 300mm. Assuming that the veneer will be in a location that is protected from the weather we recommend MDF with a face grade veneer of your choice.

Q. A technical question. I am making a dining table for a client from recycled ironbark. The top will have a veneered panel 2400 X 800W. The client does not want paper-thin veneer so I am milling to thickness. My question is how thick can I make the veneer but still avoid seasonal movement? I'm trying to avoid the checking/splitting that would happen down the track if veneer is thick but is glued to the substrate. (I will veneer both sides of the substrate for balance) Is 5mm too thick?

There's quite a good discussion of this issue on the net at this address: Various woodworkers discuss their experience with thicker-than-usual veneers and the general consensus is that anything greater than 2-3mm is risky. As with solid wood, some species are more dimensionally stable than others, and quarter-sawn material is subject to less movement than back-sawn. If it's possible to select quarter-sawn ironbark that has been well dried, and the table is going into a stable environment, your project will have the best chance of success.

Q. I am currently in the process of creating a bespoke table for a client constructed in environmentally friendly timber and wanted to know if you could please provide me with some timber joint recommendations on how I could possibly construct the base of the table. I have provided a picture (sent separately) as I thought this may be easier for you. Are there any recommendations on the type of hardware I could utilize e.g specific types of screws or nails etc? I also would like to point out that it is required to be flat pack in design.

The easiest way to construct the base of the table would be to make up the cross-shaped pedestal out of two flat pieces joined with an edge cross lap, commonly known as an "egg-crate" joint. This technique is explained in Popular Mechanics magazine of March 1994, p. 79, available on the net. One point we noticed from your picture was that the grain radiates out from the centre of the table. This provides an attractive pattern but there would be less potential for movement if the grain ran the other way. Wood only swells and shrinks across the grain, not along the grain. However, if the wood is properly dried and sealed all round (top and bottom) no doubt your design will be OK.

Q. I am trying to identify the type of wood I have on a large boardroom table. It is a type of Birdseye burl but I can't identify it. It is quite distinctive and should be identifiable from a photo I have.

Identifying a veneer from a photo can be difficult and is best handled by someone with specialised knowledge. We suggest you put the question to an experienced person in the veneer industry who handles veneers on a regular basis. Briggs Veneers in Sydney, phone (02) 9732 7888, should be able to help.


Did you know?

About 6% of Australia’s 147 million hectares of native forests are public forests potentially available for timber harvesting. Timber is harvested from about 1% of those public native forests each year.