Here at Slack Bag Coffee we're always looking for ways to make Home Roasting as accessible as possible. Sure you can spend $100's or even $1000's on kit and get really nerdy, but we think that doesn't make it very approachable.
We ran across using a Hot Air Gun and a Flour Sifter on the internet, and thought we'd give it a try!
First off, this was an interesting setup, because opposed to our other methods we've tried here on the Slack Bag blog, cast iron pan, and wok, this method only uses hot air for heating the coffee, rather than surface contact. So we're approaching roasting in a completely different way from a heat transfer perspective.
One thing about roasting with hot air is that it can provide for a more even roast between the inside and the outside of the bean. Think about baking a steak instead of searing it. Most of us would probably never do that, but in this case it may not be as bad as your thinking. This can give us incredibly smooth, and even coffee's, and if you like a nice medium/dark roast with body development, and sweetness then this may be up your ally.
Let's check out the setup!
I chose to do this roast on my grill outside for a couple of reasons. First, you can see that I was able to position the Hot Air Gun so that I do not have to hold it. This came in very handy as I needed to use my hands, primarily to shake the flour sifter, but also to take the photos! For my roast, I turned the hot air gun to high and then shook the beans in the flour sifter continuously. This got me to first crack in about 8 minutes, and 2nd crack in about 10-11 minutes.
On my first try, I had some scorching as I was not circulating the beans enough. Unfortunately this model of flour sifters wire is not strong enough to stir the beans thoroughly. This meant that shaking was the only way to get those beans moving enough to create an even roast.
Overall however, I thought that shaking the beans was easier than stirring, although my batch size is limited to about 200g vs the 2lbs I can do in my wok. However, with the faster batch times, I can get a reasonable output. With the wok taking about 18 mins to do a 2lbs, and the flour sifter doing a little over 1lb in 3 batches at about the same amount of time.
Are you going to try it? Happy Roasting!
We enjoyed playing with this method, and perhaps we'll upgrade our Hot Air Gun and Flour Sifter setup as we go along.