A GUIDE TO BUILDING ICONIC AUSSIE GUM TREES a step by step guide to modelling the symbolic trees of Australia, with Dan Pickard
About these humble gum trees... Gum trees are the essence of the Australian flora. It just wouldn’t be Aussie if there wasn’t a gum tree almost everywhere within eye sight. There is in excess of 700 varieties of gums (or eucalyptus to more politically correct) found on this planet, with only two of those species NOT found in our backyard! Even Australians who wouldn’t know a Banksia from a Begonia, would still probably know what a gum tree looks and smells like. Most Aussie’s may not be able to identify a particular species, but they will know “thats a eucaluypt”. That term “gum tree” also comes from the habit of many of the eucalypt species to ooze a sticky, gum-like substance from the trunk, hence becoming the generic term for most eucalypts. With so many varieties of trees around, the models I describe today should be considered a fairly generic version of the tree. Some of the more common varieties of gum trees found around us include Manna Gum (also known as White Gum, or Ribbon Gum), River Red Gum, Snow Gum, Grey Gum, Stringybark, Scribbly Gum, Spotted Gum, Ghost Gum, Mallee Gum and Ironbark. There is also the giant varieties, which include Mountain Ash, Messmate and Tasmainian Oak. If I were to place a general variety name to the trees I will describe modelling in this clinic, they would probably be considered either Manna Gum or Mallee Gum (as well as some of the larger Mountain Ash variety). I would like to point out that this is my twist on modelling a gum tree, but there are ceratinly some other excellent methods out there, previously well described by some fellow local modellers. Two of which have inspired myself to develop this method, are Murray Scholz and Rod Hutchinson. Murray provided a clinic at the 2007 Australian Narrow Gauge Convention on modelling wire and clay trees, as suitable versions of more gnarly trunked Red Gum (technique also described in Narrow Gauge Downunder #26, July 2007). Rod has also conducted various clinics at Narrow Gauge Conventions, with a focus more on HO scale tree and scenery techniques. I must also make time to mention of two other local modellers who have been a significant influence to me in the development of these models. Firstly, Alan Rocket, whose depiction of Australian scenery in his “Puffing Billy” tribute has undoubtably inspired many. Secondly, John Hunter, who has also been an early influence to me personally (almost a mentor in many ways), and was one of the first to demonstrate to me what can be done with a dried up old sedum cutting. I have simply taken what I have seen, learnt and enjoyed over the years, to develop my method, which I hope you will find useful in your own modelling.
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A GUIDE TO BUILDING ICONIC AUSSIE GUM TREES a step by step guide to modelling the symbolic trees of Australia, with Dan Pickard
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About Sedum “Autumn Joy”... These gum trees started life as a vibrant succulent plant, known as Sedum “Autumn Joy” (photo 1), a drought hardy flowering plant, with long stems covered in thick leathery leaves. The flower heads open as green, broccoli looking blooms, which then progress from pink to red heads (photo 2), that can be long lasting in the garden. Once the flower head dies off, a hollow woody stem remains, with a dried brown flower head...the starting point for these model gum trees. For best drying, leave the flower head and stem on the plant as long as possible. The stems can however be pruned while still a bit green, and then gently laid into a box/tub (photo 4) to continue drying (allow a couple of extra weeks once cut). Your garden will look a little neglected, but at least your gum trees will look great. For the garden lovers, growing is fairly simple (which is handy if your interest is modelling, rather than gardening). Once the flowering season is complete, the stems can be pruned back to ground level, where evidence of the coming seasons growth will be found. The plant can be easily split and transplanted. Photo 3 shows the start of the new seasons growth, soon after taking another crop of gum trees. page 2
A GUIDE TO BUILDING ICONIC AUSSIE GUM TREES a step by step guide to modelling the symbolic trees of Australia, with Dan Pickard
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The materials you’ll need... Apart from the dried sedum cuttings, there are a number of materials needed to shape up these trees. The list seems extensive, but most items you are likely to have amongst your modelling items already. Acrylic paints - tubes are easy to use, and you’ll need reasonable volumes. I prefer “Jo Sonja’s” (burnt umber, skin tone, smoked pearl, napthol crimson and cadmium yellow) and “Kaiser” (eggshell, pale beige, mud puddle). Additional suitable green acrylics can be used in the optional airbrushing stage. Enamel spray paints - A flat white undercoat (cheapest available), and some “White Knight - Rivergum”. Oil paints - acrylics can be used, but oils give far better control with this effect. Low to medium priced oils are certainly suitable for this application (burnt umber, paynes grey), as well as some turpentine (use low odour if modelling indoors). Wire - various gauges (0.9 & 1.25 mm). Glue - “Liquid Nails”, easiest used from a smaller tube. Tools - Pinvice (plus 1-1.5 mm drill bit), blade, tweezers, pliers/wire cutters, palette knife (optional) and an airbrush (optional). Modelling clay - various air dry clays are suitable (“Jovi” or “Das” are the most commonly available). Modelling paste - available at good art shops, and low price brands are suitable to use here. Dowel timber - pine dowel lengths in various sizes (6-8 mm), cut to suitable length for trunk bases. Sandpaper - fairly coarse grit (60-100 grit) for cleaning back the sedum stems. Paintbrush - various style (small chisel, medium chisel, small point, fan etc). page 3
A GUIDE TO BUILDING ICONIC AUSSIE GUM TREES a step by step guide to modelling the symbolic trees of Australia, with Dan Pickard
A couple of prototypes for reference...
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A GUIDE TO BUILDING ICONIC AUSSIE GUM TREES a step by step guide to modelling the symbolic trees of Australia, with Dan Pickard
Lets get cracking and knock out a tree...
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Now this step by step guide may seem a bit long and wordy, but I’ll include plenty of photos, and try to put this method into words as best detailed as possible. Starting with your dried sedum cuttings, select one of the larger stems, which will become the main trunk. This guide is for building a gum about 40-60’ tall (about 10-15”, or 25-40 cm, in O scale), but sizing is a variable choice. Sedum’s seem quite prone to aphid attack (photo 15), which are easily cleaned off from the dried stem using a brush (I use either an old fan brush, or even an old toothbrush). Next, the stem needs to be roughly sanded with the coarse grit sandpaper, to remove the small knobs left from the removed leaf stems (photo 16). The sanding is quick, only needing a few passes to remove the knobs. After these knobs are sanded back, they kind of ressemble old knot holes. The clean up process sounds a bit fiddly, but really is quite fast. The dried sedum stems are surprisingly robust, and can easily tolerate being knocked around during this process, without losing all their fine dried flower heads. For easy mounting of the tree, both while building and also when planting in final scene, use some of the short lengths of dowel to insert into the hollow stem of the selected trunk cutting. Select which ever size dowel is the best fit (6-8 mm dowels will suit most larger stems), squirt some glue into the hollow opening (photo 17), and then insert the dowel. The easiest way to do this, is just insert the dowel until it stops and then use some cutters/pliers to cut the excess dowel length. Leave about 2” (5 cm) of dowel as your tree mounting pin. Next up, the grafting process begins to shape this tree. page 5
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A GUIDE TO BUILDING ICONIC AUSSIE GUM TREES a step by step guide to modelling the symbolic trees of Australia, with Dan Pickard
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At this point (photo 19), we have the shape of our basic gum tree. This is a suitable point for many of the modelled trees to actual stop the shaping process, and start the colouring stage. Not every gum tree in a scene is going to be a mature 60’ feature. There are always plenty of surrounding younger sappling trees to fill out the scene. Trees modelled to this stage are fairly quick and simple to construct, but we’ll move on and start grafting a larger, more dominant tree. Collect a few smaller dried sedum cuttings, and start bunching together (photo 20) to get a rough idea of the shape you want, a bit like arranging flowers (can be handy to mark these points for future drilling). There is no strict rule on how full the head of these trees should look. In nature, the shape and balance of the foliage tends to vary considerably, so don’t be afraid to leave gaps in the canopy, or have a heavier side to the tree. These variation in shapes will actually add to the scene once planted out.
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When happy with how the head of the tree could be bulked out, use a blade to cut the grafting stem at a suitable angle (photo 21), so when mounted on the main trunk it will sit at an upward growing angle. Keep the trimmed scraps of sedum stem, as they can be used in one of the next stages of shaping the trunk. Next, cut a length of which ever gauge of wire (0.9-1.25 mm) will slide comfortably into the hollow grafting stem. Roughly straighten the wire and then insert into the grafting limb. No need to glue the wire in (slide it in as far as the hollow stem will allow so it should wedge in fairly firm), and then trim the excess wire with the pliers (photo 22), leaving about 2” (5 cm). This wire forms both a mounting pin for the new limb, and also adds good rigid strength to the finer sedum cutting. Use the pinvice and suitable size drill bit (1 - 1.5 mm, depending on which gauge wire was used for the grafting stem), to drill mounting holes into the main trunk, ready for inserting the wire from the grafting limbs into. Photo 23 page 6
A GUIDE TO BUILDING ICONIC AUSSIE GUM TREES a step by step guide to modelling the symbolic trees of Australia, with Dan Pickard
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With the wired grafting limbs prepared, its time to start growing this gum tree (photo 24). A tip to make inserting the wires easier, is to curve the protruding wire downwards from the angle the new limb will sit on the main trunk. The wire should feed in much easier, with less chance of piercing though the other side of the trunk when pushing it in. The slight curve to the wire will also act like a bit of a spring, helping to hold the grafted limb in place until ready for the glueing stage. Be mindful of how far the main trunk’s dowel insert extends up the main trunk. If you are struggling to feed the graft wire down the trunk, chances are the dowel is obstructing its path (just shorten the wire if neccessary). Work your way around your main trunk, adding the new limbs to the previously drilled holes, and feeding the new limbs down until flush with the main trunk (photo 25). On average, I guess I would add maybe 4-6 of these grafted limbs to bulk up these larger gums, depending on how “complete” the limb spread was on the chosen main trunk cutting. It can be seen (photo 26) how just a couple of grafted limbs makes a considerable difference to the bulk of the tree. From here on, some of the stages get a bit more messy (just an early warning). Time to glue the limb joints, and the easiest way is squeeze some of the “liquid nails” onto the tip of your finger, and then smear and shape the glue across the joint. A wet finger can be helpful to make the glue a bit easier to smear to shape (photo 27). Work your way around your new tree, securing all the joints. Try to shape the glue into the upper angle of the joint (photo 28) using a scrap of wire to shape if needed. Put the tree aside to let the glue dry overnight, and then spend the next few days trying removing the glue from your fingers.
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A GUIDE TO BUILDING ICONIC AUSSIE GUM TREES a step by step guide to modelling the symbolic trees of Australia, with Dan Pickard
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Once the grafted limbs have dried in place, it’s time to bulk out the main trunk a bit (and the messy work continues). I use the off cuts of the sedum cuttings to add some weight to the base of the trunk. Split the hollow cutting scraps lengthways, and glue a couple of these half round pieces to the trunk base (photo 29). Its more cost effective to bulk out the trunk with these scraps, rather than just using the modelling clay, plus the clay will dry better if applied as a thinner layer. Once the glue has dried on the trunk base additions, the air dry modelling clay can be used to further refine the shape of the trunk. A quick note on the clay; colour (white or terracotta) isn’t really important, but I find the terracotta colour easier to see how the application is finished. Pull small portions of the clay from the block and roll out to a length (photo 30). Apply the clay to the trunk, starting at the base, and using wet fingers, shape/feather the clay up the trunk (photo 31). Work around the tree, tapering the clay up as you go. The trunks are often not round, but form like a number of “tubes” rolled together, that extend into the roots and limb formations. The clay can alo be used to smooth over the glue joints of the grafted limbs. Pinch and push the clay into the desired shape of the trunk, and then give a general smoothing over with wet fingers (photo 32). Drying time for the clay will depend on how thick it was applied. A thickness of around 3-5 mm should dry overnight. Thicker applications of clay may lead to uneven drying and cracking of the surface. As indicated here (photo 33) by the red markings, the previously grafted extra limbs, have now been blended into the contours of the tree trunk.
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A GUIDE TO BUILDING ICONIC AUSSIE GUM TREES a step by step guide to modelling the symbolic trees of Australia, with Dan Pickard
This nearly finishes the tree shaping stage. A couple of optional steps can occur prior to the painting stage. While applying clay to the trunk, you may choose to extend some roots (photo 34), but most of these will be covered once planted into the scene. Another extra step I like to take is thinning out the canopy a bit. Most real trees have plenty of holes in the foliage canopy, allowing light to stream through. Take a pair of tweezers, and pluck some of the dried flower heads out of you shaped tree (photo 35). This can be quick and quite random, and will add nicely to the overall effect. Photo 34
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Time then to pull out the paints. You may choose to give the whole tree an overall spray with diluted PVA, but I haven’t found it neccessary with the trees I have made. A couple of coats of spray paint tends to add a good bonding layer anyway. First, give the whole tree a spray of white undercoat (photo 36), and allow to dry. Next stage of painting, is pre-colouring of the foliage. Use the “White Knite - Rivergum” spraypaint as a base colour, remembering to also spray the underside of the canopy (photo 37). By using the white undercoat first, the green paint will cover better, and maintain its green tones better, staying more vibrant. The white undercoat is also the starting point for the natural colour of the trees limbs. The tree starts to come to life (photo 38) even after this initial addition of some colour.
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A GUIDE TO BUILDING ICONIC AUSSIE GUM TREES a step by step guide to modelling the symbolic trees of Australia, with Dan Pickard
Colour is one of the primary features of a gum tree that makes them unique (at least to my eyes). The “Rivergum” green makes a good starting point for the foliage colour, but certainly can be further enhanced with some airbrushing. I just use a sample pot of common house paint acrylic for this colouring. The green I use here is “British Paints - Football Ground”, diluted down with windshield fluid, for use through the airbrush. Spray across the base colour green of the canopy. It doesn’t have to be perfect coverage, as that bit of colour contrast is actually desired. To add further depth to this foliage colour, I next add a hint of the “cadmium yellow” to the airbrush green mix, and highlight patches of the canopy. This colouring can still be further addressed by adding some of the “napthol crimson” to the airbrush green mixture. This crimson/green mix, when sprayed across the canopy at a low angle, picks up the tips of the foliage, providing a hint of the new growth leaves. A heavier application of this crimson colouring can represent the harsher sunburnt colourings that these leaves take on in our more hotter environments. Understandably, not everyone has an airbrush. Alternatively, the same colours can be gently drybrushed onto the canopy, using a medium size fan brush (the dried flower heads are robust enough to easily tolerate the gentle pressure of drybrushing). The main point is to provide some colour contrast to the foliage, rather than leaving it a uniform shade of green across every tree. Once planting out a number of trees, each with varied degrees of foliage tones, the effect is much more natural to the eye.
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This next stage will be time consuming and fiddly (and probably make your eyes go a bit wierd), but the effect of the contrasting foliage/limb colours is rewarding. There will be plenty of green overspray from colouring of the foliage (photo 39). The upper armatures of most gum trees generally are a grey/ green/flesh type of tone. Here, the advantage of the cheaper thin coverage of the “Kaiser - eggshell” paint is useful. Hold your tree upside down, then using a small brush, start to paint out the oversprayed green (photo 40). The cheap acrylic only covers out the green about 3/4, leaving a hint of the green bleeding through. This poor coverage works to our favour, by representing the newer “green” growth of the tree. Once the finer armature ends have been painted out, change to a larger brush for quicker coverage of the thicker limbs and trunk. Again with the gum tree colourings, there is a broad spectrum of colour in the bark (refer back to page 4, photo 10). After the initial “eggshell” (grey) toning, streak washes (think wet drybrushing...) of the “mud puddle” (brown), “pale beige” and “flesh tone” up the trunk. Continue this pale bark tones down the trunk, and then set aside to dry. Now its starting to feel like a gum tree. page 10
A GUIDE TO BUILDING ICONIC AUSSIE GUM TREES a step by step guide to modelling the symbolic trees of Australia, with Dan Pickard
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One of the unusual features of a gum tree, is the “half bark” contrast that happens on the trunk of many varieties. The upper trunk and limbs have a smooth, fleshy finish, while the base of the trunk has a completely opposite texture, with roughly knobbled ripples of bark, often found as peeling strips (page 4, photos 11 & 14). As well as the textural change, it is also a high contrast colour change, from the heavy black, browns, greys of the lower barks, to the whites, greens and fleshy tones of the upper limbs. To model this change, I use “modelling paste”, which is a bit like a soupy plaster mix, for adding the rough texture. Easiest applied with a small palette knife, start to smear some of the paste around the base of the tree (photo 41). To get the rippling texture, use the edge of the palette knife in a chopping action (photo 42), to add the vertical ripples in the bark, and feather some of the texture up the trunk. You can then drag back down through the applied paste with the tip of the knife to add further texture, and then leave to dry overnight. Once dry, the lower bark section can be coloured with acrylics. I usually start with a general application of black/burnt umber, followed by drybrushing with raw sienna, nimbus grey, and even some of the flesh tone (photo 43). To this point, the tree could be called complete, but there is ways to further enhance the gum tree look.
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A GUIDE TO BUILDING ICONIC AUSSIE GUM TREES a step by step guide to modelling the symbolic trees of Australia, with Dan Pickard
Bleeding rust...I mean sap Time to pull out the oil paints, and add some of the “gum” to this tree. At break points in the trees skin (old knots, where limbs protrude, growth splits etc), these trees essentially bleed sap (refer to page 4, photo 12). After spending much time looking at these trees, trying to decide how best to model them, I eventually likened the sap ooze and subsequent staining of the trunk to the colour of rust. So why not essentially rust up this tree in the same way I might apply rust to modelled metal? These trees bleed rust. As mentioned earlier, these don’t need to be top quality oil paints (we are not painting a masterpiece here). Many people seem afraid of oils, as costly, but a small spot of oil paint goes much further than acrylic, and think they’re difficult to use. Actually, in many ways they are easier than other paints, as they can be pushed, pulled and moved to where you want them. This step, as it turns out, is almost one of the easiest stages of modelling these trees. Start by sqeezing a small amount of oil paint onto your palette. I use mainly “burnt umber” for this process, but can also add some “burnt sienna” to the mix. Pick up a small portion of oil on the tip of a pointed brush, and apply spots of the paint to trunk and limbs (photo 44), at those places mentioned where it is common to have the bleeding sap. These initial spots of oil paint need only be small, as these create the streaked sap stains down the trunk. Dip your brush into some turps, and then dab onto the tree just above your previously applied paint spots (photo 45). As the turps run down the tree and through the oil paint, the “rust” colour will bleed down the tree with gravity. This can be further promoted with gentle feathering of the paint down the trunk (essentially a thin oil wash). The oils give a far softer staining effect than using acrylics for this task. Once satisfied with the initial rusty sap runs, return to the areas that the first spots of oil paint were applied, and re-apply some heavier spots of the paint, simulating the thick sap collections (photo 46). For me, this simple application of colour to the trunk is one of the main steps that really brings these trees to life, creating that distinctly characteristic gum tree multi-tonal bark colour. page 12
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A GUIDE TO BUILDING ICONIC AUSSIE GUM TREES a step by step guide to modelling the symbolic trees of Australia, with Dan Pickard
Messy fingers, smelly paint...and now a tree
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This pretty well leaves us with our first completed iconic Aussie gum tree. Like I said, the process sounds a bit long, but once familiar with the steps, total work time for one of these larger trees will be approximately 1-1.5 hours (not including drying times). I also make many smaller trees, consisting of just a single sedum cutting, so no time involved in the grafting steps, but the colouring process is exactly the same. Photos 47, 48 and 49 illustrate some of the finished efforts. The typical shades of the trunk colourings, textural variations from rough to smooth, and finally a small “nursery” of model gum trees awaiting a scene to be planted in (including a hint of a Mountain Ash in the background). You can pack up all your mess and call it job done...unless you’re mad enough to want to try and put the bark onto your model gum tree.
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A GUIDE TO BUILDING ICONIC AUSSIE GUM TREES a step by step guide to modelling the symbolic trees of Australia, with Dan Pickard
If you’re a bit nuts, and really love trees...
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I have included this next stage, described as a kind of “bonus round”. I tend to reserve this extra level of detailing mainly for those trees that will become more dominant features of a scene (ie larger foreground trees, or isolated scenic settings). For those of you keen to go that one step further, I suggest head down to the garden section of your local hardware store to find some Bark Roll (photo 50), a sheet bark material, normally for lining a hanging basket. This bark consists of several layers, but we are interested in the long fibre strand layer (photo 51), which works nicely as a representation of our gum trees peeling bark strips. Carefully peel back some of the papery rear layer from a small section of the bark roll (photo 52). Be delicate, as its a fairly fragile material once the layers are parted. The whole backing layer doesn’t need to be removed, but just enough to expose some overhanging long strands (photo 53). It is much easier to work with small sections of this bark sheet (no more than 2-3” wide, or 5-7 cm). Save the loose fibres that fall off, as these can be used at a later stage, as bark litter around the base of the tree, once planted into the final scene.
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A GUIDE TO BUILDING ICONIC AUSSIE GUM TREES a step by step guide to modelling the symbolic trees of Australia, with Dan Pickard
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Next, take the small section of peeled sheet, test fit to the tree base, and then I normally use a smear of superglue for a fast grab tack to hold the bark piece to the trunk. It may need 2-3 pieces to work around the tree base (photo 54). Given the delicate nature of the bark sheet, a light brushing of dilute PVA will toughen and seal the bark skin a little. Once dry, I use thin washes of burnt umber acrylic (a wash is more gentle to apply at this fragile stage), to gain the initial contrasting bark tones. Several light washes are better than one heavy flooding. Once dry, various additional light washes of raw sienna, burnt sienna and greys can further enhance the this rough bark effect. A final light drybrushing of some flesh tone will help to highlight the depth of this rough bark base (photo 55).
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This then really completes the tree..finally. As I said, not suggested to use this extra finish for every tree (unless you really are totally mad), but works very well to make great feature trees. For finishing the tree in the scene, remember the details around the tree as well. Long grass growing up to the foot of the tree acts like a net, collecting leaf and bark litter (dried tea leaves or commercial leaf scatter, and scraps of the bark roll), as well as fallen limbs and twigs from above. Gum trees also often grow in a bit of a clump, so several closely planted tree models (several large, surrounded by a number of smaller sappling trees) will create a fairly natural looking bush scene. page 15
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A GUIDE TO BUILDING ICONIC AUSSIE GUM TREES a step by step guide to modelling the symbolic trees of Australia, with Dan Pickard
So thanks for joining me... I hope that you have found this guide clear and useful. I’ll leave you with a few more images of what makes a gum tree so special. They are so much more than a brown trunk and green leaves, so get your hands dirty, and have a go at capturing some of the true colours of our Aussie bush. Cheers, Dan Pickard.
And never let anyone tell you your trees look too big... page 16