The high levels of tannin in black wattle makes the wood rich red in colour. A beautiful stable timber, it grows well in low rainfall, and was once widespread, thriving in the heavy clays of the basalt plain that extends from the outskirts of Melbourne to beyond the South Australian border. As a common local timber, we thought it was an ideal candidate for the flooring and window frames in the 21C drop slab hut.
From settlement’s outset, however, black wattle (Acacia mearnsii) was consigned to a low value destiny – similar to sugar gum. With its bark found to contain 40 per cent water-soluble tannin, industry seized on it as ideal for cleaning and preserving animal skins. Countless numbers of black wattle were flayed alive, with their bark stripped and bundled up for making leather or scouring sheepskins in the cities’ tanneries.
Sent overseas for its tannin qualities, black wattle soon developed a poor reputation. From South Africa to Germany, it became regarded as an invasive weed. Its tough black seeds readily germinate once damaged. After fire, it suckers prolifically creating dense thickets that eliminate other species. Around 15yo, the species becomes untidy, literally falling apart.
Tainted by its past, the best that agroforestry manuals can recommend for black wattle is to plant it as a nurse crop for more valuable timber species. When grown in alternate rows, the fast growing black wattle forces the more favoured species of eucalypt or exotic timber to grow straight as they strive to reach the sun. After 5-10 years, the manuals recommend cutting out the black wattle for firewood.
At his property near Mt Egerton, Ballarat Region Treegrower (BRT) farm forester, Campbell Mercer, put this formula into practice. In 2003, he planted a 20 acre woodlot of black wattle nursing a range of species from brown stringybark to cypress.
Fifteen years on, the black wattle was outcompeting everything else on a wet, south-facing slope. Encouraged by BRT’s resident pruning fanatic, Phil Kinghorn, Campbell had over the years pruned some of the black wattle and he thought: “There must be a better use than firewood, particularly as some of the trunks are in excess of 20cm and clear to 10’.”
Using Phil Kinghorn’s mobile Lucas Mill, they produced some 1” and 2” boards with ease. There was no shrinkage or end checking and the milled boards had a distinctive wavy grain pattern and swirls of dark red. They sent the boards to specialist timber retailer, Fairwood, in Melbourne for appraisal.
“Maybe it’s something to do with the tree being naturally very branchy, making it totally unsuitable for timber unless pruned.”
Campbell and Phil went on to mill six cubic metres of 1”and 2” boards of black wattle. We are the first to buy the boards, with Lachie picking up 92 lineal metres on a fine day this spring. When he finishes them for flooring and frames, who knows what standard they might reach? We’ll keep you posted!