So I've been attempting to home roast w/ a humble heat gun (Wagner 1200) and shiny dog bowl for a few months now. I've had limited success with a few Sweet Maria's espresso blends (Liquid Amber being my current favorite) but I can't seem to get a decent roast with the Sumatra FTO Aceh that I can only imagine would be a wonderful coffee if I could roast it properly.

I do my best to keep the heat gun a consistent distance above the beans (I try for about an inch above) and stir frequently to churn the beans. My problem is that I've been roasting the beans for 30+ minutes and the bean color looks right for a FC roast, but once the beans cool they have a grassy smell and an even grassier, muddled taste. There seems to be quite a bit of silvery skin on the beans that doesn't too well blow off as chaff with the heat gun. Is it possible that the gun doesn't blow w/ enough force? Any other suggestions? I'm open to about anything (that doesn't cost crazy money--I'm a grad student w/ some tight finances). Thanks for any help you can give me!

I don't have any experience on a dog bowl/heat gun setup, but thirty minutes is an extremely long roast time. If I did that on my drum roaster, my coffee would be baked. Would it be possible for you to speed it up? I would recommend trying a fifteen minute roast time.

It's surprising that you're still getting a grassy taste after such a long roast. How long are you letting the drying phase (the period of time from when you begin to apply heat until the beans turn bright yellow) last? Grassy tastes are usually a result of too short of a drying phase. Also, how long are you letting the beans roast after the first crack?

Sumatran coffees can sometimes be herby and earthy. Could you perhaps be confusing these tastes with grassiness? Is the grassiness you're tasting astringent and unpleasant?

I had the same problem with chaff on my old Gene Cafe. I found that tossing the beans in a colander in front of a fan on the "high" setting got rid of most of it. A small amount of chaff isn't too big of a problem as far as taste goes, though.

Roman is right on most his points; but if I remember it right, I think good heat gun roasts generally tend to take longer than drum roasts. Hope someone with experience in the method will chime in.

In an extended cool roast, the sugars will caramelize, and the beans get darker, even if they never hit the first crack. This is what Roman meant by baking. A baked Sumatra will be very "foresty" tasting, I think.

Most Sumatras taste a lot better in a rolling second crack roast than earlier; you should focus on getting your beans that hot. This means you should be getting a lot of oily smoke and rapid crackling as you end the roast. You should be shooting for at the most 20 minutes to get there. If you can't get the beans to that roast color in that time, you will need to roast hotter and/or cut your load.

I'm not saying you should roast everything that dark; but you're doing something wrong if you cannot get any roast that dark.

Thanks for the help! I'll look to get outside tomorrow morning (provided that we're not snowed in) and see if I can ramp up the heat a little and get it into second crack at around 20 minutes. If anyone has any secrets (if only!) they'd want to share, I'll happily listen. Again, thanks for all the help from this site so far in my coffee experience.

Roasting outdoors in the winter will really stretch out the roast times. One trick is to cover the roasting device in a cardboard box so the surrounding air warms up; but I have no clue how to adapt that to heat gunning.

Since it's been a little warmer around these parts, I've been able to get out and roast a little bit with much better results. I think that I wasn't keeping the heat gun close enough to the beans and I was removing it frequently to stir. I stirred a little less and kept the gun closer and had much better results. First crack came at about 9 minutes and it was just starting the second crack at about 15 minutes. I'll keep tinkering with it, but for now I have some drinkable super-fresh coffee. Thanks for all your help!