Australian AIR

Today while sitting outside the hotel feasting on a horrible sarmie, we where greeted by a stranger called Scott.  Scott spotted the WRC documents that Gerald, our roasting competitor, was studying with and took the liberty of introducing himself.  Turns out that Scott is also one of only 8 World Roasting Championship competitors and we soon wheeled him in to join us for supper.  Scott owns a roastery in Sidney called Australian Independent Roasters.

On the walk to the restaurant, Scott and I had the most interesting conversation about coffee roasters.  His passion for roasting is infectious and his knowledge about machines are endless.  We discussed burner configurations, air flow, drum materials and variable control motors and fans.  It was so interesting to hear many of my theories confirmed (and dismissed) by his first hand experience with different roaster systems.

Control is key

It’s not often that you come across a roast master who actually wants a high level of control over his roaster. Most roasters that I know simply open up the taps and wait for beans to turn brown. Scott, like our own Gerald, likes to take roaster control to the next level. They want variable speed drums and fans to manipulate even the tiniest detail of each roast. For them, a simple 10% increment burner control system would not suffice and pressure sensors for air flow is a must. Not to mention electronics!

The perils of heat distribution

Scott’s main concern with his roaster was even burner heat distribution. He argued that the old school Probat burners gave a more even heat distribution compared to many modern blade burners.  In particular, his Joper’s 3 blade burners runs the length of the drum and is spaced evenly underneath the drum.  But this configuration causes the middle burner to be closer to the drum than the other 2.  The direct flame causes hot spots on the drum which reduces his even heat distribution and control in the system.

Ceramics, metallurgy and coffee

Probat has solved this problem long ago by using a thin gauge buffer plate between the burner and the drum. This configuration reduces hot spots on the drum, but ultimately also affects the response time to any changes in the burner pressure. The other configuration that we discussed was the dual-wall drum; the drum has 2 layers separated by thin air gap in-between the 2 steel cylinders. The 2 layers can be made of different types of such as mild and stainless steel or even brass. The theory behind dual-walled drums make sense, but they are extremely difficult to build and will most likely not give you much better results than the cheaper buffer plate option. I introduced Scott to my system where we use a super heat distributing ceramic to coat a 5mm mild steel drum. This gives the roaster an incredibly fast response time and adds a little heat retention to a material that would otherwise lose its energy quite quickly. Scott seemed intrigued by the idea, but for roast masters like him the only way is by trying it out for himself…maybe I should send a roaster his way?

In the end, it was an absolute pleasure sharing ideas with an experienced roast master like Scott. His love for roasting and attention to detail in his method is inspiring. I wish Scott all the best for his performance in the WRC. Perhaps we will meet again!