Look across any Australian grain-receival site and the covers are all the same colour: a pale, sky-like ice-blue. That uniformity is not a matter of fashion. It is the result of testing that settled an argument the industry had been having for years.
In the early days, as Jaylon CEO Stephen Lloyd recounts, the farmer’s co-operatives bought whatever grain cover material was available: “some colours I recall were dark-green, red, orange and dark-blue.” The problem was heat. More than 30 years ago Wayne Owens (SACBH) investigated the best colour for grain covers and found that dark fabrics “got so hot that the coatings could even begin to melt, leaving foot prints along the bunker ridge.” The covers became too hot for site staff to handle, and more seriously, too hot for the grain, “significant heat was getting transferred down to the top 200-300 mm,” on occasions triggering premature germination of barley and shortening the cover’s service life.
That pointed to white as the coolest option and South Australia adopted it briefly. But white brought its own problems. As Lloyd recalls, the glare interfered with deployment and caused eye-safety concern, locals complained it was an eyesore on the horizon, and “the police judged the white was causing driver distraction.” The answer was a colour close to white but not white, one that “blended with the sky until it got dirty,” at which point it blended with the ground. That colour became ‘ice-blue’.
The hard data arrived in the summer of 1997-98, when Owens ran a controlled trial at Tailem Bend, stitching a green tarp and a new ice-blue tarp side by side on the same bunker and logging the temperature under each. The result was stark. On 22 January the green tarp reached 71°C, while the blue reached 44°C. As Owens wrote, “this alone was enough to make the change in colour to ice blue tarps, as it meant the difference between personnel being able to handle them or not.” The trial also found that as the tarp heated, relative humidity in the top 500 mm of grain rose. This was an early insight into why the top of a hot bunker benefits from ventilation.
Jaylon’s part was to take that finding and make it the standard. Working from SA’s results, Jaylon began converting the growers’ co-operatives nationally to the new colour. “CBH (WA) was the first to follow.” With its fabric manufacturers, Jaylon locked-in not just the ice-blue colour, but also a common base-cloth and coating formulation across the industry. Blue pigment is not the cheapest, and a switch to “ice-green” was once considered, but as Stephen notes, “the saving was marginal, and our customers had come to know and trust ice-blue.”
So the colour on every bunker is really a piece of applied research, chosen because it keeps covers cooler, is safer to handle, and is easier on the grain underneath.