Finishing by Species

Above: Different species can require a different approach to finishing. Wombat samples in white beech, beefwood, Tasmanian blackwood and Huon pine.

Words and photos: Carol Russell

One of the things that keeps me so engaged with woodcarving, is the different personalities of the various timber species and the amazing variation within those species. Each piece I carve is unique in grain, colour and texture.

Considerations

Deciding how to finish carvings is rarely straightforward because it depends on the features and grain you’re dealing with. Each timber species has a unique set of characteristics and the finish you choose, and how to apply it, will depend on several things:

• Is it a dark or light timber?
• Is the grain open, or dense and fine grained?
• Is the wood compressed, or does it contain burl or spalting?
• Is the timber naturally oily or waxy, or is it dry and a bit papery?
• Does the timber have a strong medullary ray, and if so, is it quartersawn where the rays are elongated?
• Is the timber highly figured or inconsistent in density as it might be if it has spalting or strongly defined growth rings?
• Do I want a low sheen finish or a highlighted, slightly shinier one?

Materials

I’ll be using blonde de-waxed shellac, chosen for its ability to keep a more natural colour. I make a finishing wax using one of the seed oils such as flaxseed, hemp seed or grapeseed and beeswax. My recipe is one part beeswax and three parts of any of these oils. I heat the oil in a pan and add the wax and stir it through, it’s a lovely mix. There’s plenty of other recipes around but I really like this one, the seed oils will cure and the finished surface won’t be oily to the touch.

I’m a bit stuck in my ways with these products, I know them well and understand how they work with all the different timber species. However, if you prefer one of the plant-based oils on the market and don’t want to use shellac, these preparation techniques will also work.

No two pieces are the same

The look of the timber will not only vary depending on species but also how a log was cut, how old the tree is, and whether the grain is under tension, creating compressed grain or fiddleback.

Huon pine for example can be as light as paper or as hard as a rock, so it’s important to know that within the same species the variation can be vast and the ability to absorb or repel a finish is affected. Shellac is excellent for evening up the texture of the surface, such as you’ll get with spalting or quartersawn timber with broad medullary rays. It hardens the fibres and fills the softer more absorbent areas.

Wombat species

1. Four species selected as examples of different characteristics, from top: white beech, blackwood, beefwood and Huon pine.

2. Each species has their own carving characteristics.

I’ve carved four of my little wombat forms in Australian timber species which represent many of the common features you’ll encounter (photos 1, 2). Even if you’re using recycled timber and don’t know the species, you can apply these principles by observing its grain and dominant characteristics.

For my wombat family I’ve chosen:

• Tasmanian blackwood (Acacia melanoxylon): Hard, open grain, dark with strong figure, dryish, not oily or waxy
• Huon pine (Lagarostrobos franklinii): Very light, fine, variable grain with distinctive figure, oily
• White beech (Gmelina leichardtii): Light in colour (sometimes greyish), grainy but also waxy
• Quartersawn beefwood (Grevillia striata): Very hard and dense, dark reddish with strong medullary rays, quartersawn to show broad flecks. Neither waxy nor papery but has inconsistent texture between the rays.

Sanding stages are key

3. Tools for sanding and burnishing: open mesh sandpaper, straw dusting off brush, Japanese straw uzukuri, packing paper.

For these wombat forms, I choose smooth, sanded surfaces to highlight grain, line and shadow. I sand to at least 400 grit. I prefer to use a good quality mesh sandpaper; it’s slower to degrade, the particles stay sharp for longer and the scratches are easier to remove (photo 3).

4. Sandpaper can leave scratches which need to be removed.

I spend a lot of time on the coarser grades such as 120 grit. It’s important to me that all the tool marks I want to sand out are taken away at this point (photo 4). If the timber is very hard or the tool marks too pronounced, I’ll start with a rasp to level them off.

5. Using methylated spirits to raise the grain instead of water can work better for some species.

The finer sandpaper grades then just remove the scratches from the coarser grades. I sometimes use 80 grit mesh sandpaper, but the larger particles leave deep scratches so a lot of care must be taken to make sure there are none left that will show in the final finish (photo 5).

6. A sanded finish for all the wombats was chosen to highlight and compare results.

After the 120 grit, I wet the piece down to raise the grain and also highlight any flaws I might have missed. Recently I’ve switched to applying methylated spirits with a brush (100% denatured alcohol, not the hardware variety) instead of water (photo 6).

I’ve noticed that wetting down some timbers with water can take way too long to dry and can also stain. Tasmanian blackwood, for example can be tricky to wet down, the tannin can react with water and leave a greenish tinge.

Huon pine can end up a mess as the oiliness of the timber takes a long time to dry and staining from contaminated surfaces, dirty hands and pencil marks can be hard to remove. Methylated spirits evaporates very quickly, shows the faults, raises the grain and won’t discolour the surface.

After the first wet down, I move onto 180 grit sandpaper. These stages are really the key to a good finish, the result will only be as good as the preparation.

7. All sanded and ready for finish application.

From now on, you’re focussed on removing the scratches from the coarser paper. After 180 grit, I go to 240, then 320 and then 400. I wet down a couple more times during the process to make sure I’m getting out all the scratches and marks (photo 7).

Applying a finish

Huon pine requires extra care when finishing. The Huon wombat should be looking quite burnished by now with no apparent scratches, dimples or stains. If this is the papery light Huon pine, I’d sand to 600grit to close off the fibres even more and create a very smooth surface – it can bruise very easily so care must be taken to handle it carefully. For the dense oily pieces 400 grit is fine enough, this type of Huon pine is tougher and more resilient.

When I work with this timber, I’m very conscious of washing my hands often and keeping all the surfaces around clean. One of the uniquely beautiful features of Huon is its pristine luminescence, when unfinished it has a bone-like quality and is crisp and clean.

My next step is to burnish the Huon pine wombat by rubbing it vigorously with brown packing paper or a straw burnisher, it scratches easily so you must be careful. The friction created will pull the oil to the surface and create a surface glow, sealing off the fibres.

I don’t want this little wombat to be too glossy. I’d like a warm glow, enough highlight to deepen the features but not a shine that can look like it’s just sitting on the surface.

8. Burnishing brings a glow to oily woods like Huon pine.

After applying a light coat of shellac with a brush, sand it back once it’s dry. It’s important not to get any shellac drips on raw timber as these can leave shadows under the finish. Once dry, I sand back with 600 grit sandpaper and recoat (photo 8). I usually coat Huon pine twice and then rub back, if it’s a more open-grained piece, I’d do a third coat. There always an element of judgement with every piece.

The Tasmanian blackwood and white beech used for these wombats is considerably more open grained than the Huon pine. I would still burnish them both to close off the fibres before applying the first coat, but I would give three brush coats of shellac sanded between with 600 grit paper. Filling up the grain is important, but too much shellac on the surface may give a candy apple look.

9. Burnished beefwood shows off the grain.

The beefwood is extremely dense, burnishing with brown paper helps seal and even the fibres (photo 9). The actual rays are denser that the fibres in between.

10, 11. The medullary rays of the beefwood are beautiful after the first coat of shellac.

I think two coats of brushed shellac is enough as the quartersawn rays really dominate (photos 10, 11). This wood has a relatively low rate of sinkage, meaning the finish doesn’t absorb into the grain and dull off like it does in the more open grain timbers.

12. Using shellac to raise the grain on the blackwood.

13. Rubbing back the blackwood between coats.

At this point, the little wombats have had their coats of shellac. That’s two coats for the Huon pine wombats and beefwood wombats, and three coats for the white beech and blackwood wombats due to the openness of the grain and the propensity for finishes to ‘sink’ (photo 12, 13).

From here I either want to wax and buff the finish to reduce the surface shine and create depth and softness. This is my approach to the beefwood and the Huon pine and denser timbers in general.

Alternatively, I can pull up the shine, adding depth and a glow to the overall finish with a shellac rubber or pad with a small amount of flaxseed oil on the bottom to stop the pad from sticking. This is the approach to more open grain timbers like blackwood and white beech.

I clean all the wombats with a soft cotton cloth. For the Huon and beefwood wombats, I apply the wax with the 600 grit sandpaper and buff it off with a cotton cloth. The sandpaper cuts through any rough sections and deepens the glow. It should feel beautifully smooth and if your preparation has been thorough, and there will be no marks or scratches under the finish. You can rewax in a day or so. I always like to finish over a couple days at least allowing all the materials to settle.

14. For the shellac rubber you’ll need cloth, wadding, shellac flakes (raw and mixed with methylated spirits – I use 250 grams of shellac per litre.

15–17. Making the shellac rubber.

18. Using the rubber.

To make a pad, I use a piece of clean cotton cloth with some cotton wadding in the centre, I add some shellac to the wadding and wrap the cloth around it. Photos 14–18 show how to make a shellac rubber.

19. A few drops of the flaxseed oil will lubricate the pad and reduce any drag.

Tamp off any excess onto some paper towel and the use a semi dry pad to burnish the surface. A few drops of the flaxseed oil will lubricate the pad and reduce any drag. The friction will pull up the surface a create a lovely glow, highlighting the curves and the grain (photo 19).

20–23. The processes differed to get a uniform soft glow on each of the species used.

I like to leave this surface for a couple of days until all the alcohol has completely evaporated and the finish has settled. A final buff up with some wax will finish it off beautifully (photos 20–23).

Like so many things, it’s trial and error. Experiment and make small changes to your techniques but keep your ingredients simple and build skill and awareness. I absolutely love finishing – it’s the time that you get to really showcase what a beautiful material wood can be. It’s all about enhancing the features that are naturally there.

Carol Russell @carol.a.russell is a woodcarver currently living and teaching in Melbourne. She is a regular contributor to Australian Wood Review magazine. Learn more at www.carolrussellwoodwork.com.au