wearashirt wrote:I do use LPG tanks. I actually CAN make the pressure reach 4 kPa, but the flames seem violent, or I'm just not used to it.

Roaster preference. Temp's matter, not flame size. We all differ. Didn't understand your reference to S-curve either.

... replace North regulator...

No, didn't mean that.

Boldjava wrote:Didn't understand your reference to S-curve either.

I actually only read the reference very recently on an article on perfect daily grind, where the roast profile resembles an S: drying, ramp-up, development and termination. Could be a Rao-an term? I wouldn't know.

..

The S-Curve is mentioned in a 2004 roasting article by Willem Boot originally run in Roast Magazine which you can read here: https://bootcoffee.com/wp-content/uploa ... _Mar04.pdf

Thx YakMan. I read it, book-marked it, will discuss with Joe and try a couple against my standard profile of high-growns. Always something to learn; the sticky factor of coffee.

yakster wrote:The S-Curve is mentioned in a 2004 roasting article by Willem Boot originally run in Roast Magazine which you can read here: https://bootcoffee.com/wp-content/uploa ... _Mar04.pdf

Cool we have Boot coffee at work, the first one I really like is the current Panama (made on a KvdW)

I'm curious how drum size impacts potential batch size. With a small drum the surface area is proportionately larger than the volume, but as the size increases surface area becomes proportionately smaller relative to volume. This is due to basic math and the fact that surface area is a function of pi x diameter, while volume is a function of pi x radius squared.

You can obviously put more beans in a larger drum, but when you do they will have less contact with the drum walls. So as a result a smaller drum would seem to have more conductive heating and a larger drum would have to rely more on convective heating. Might this potentially be a reason why smaller batch drum roasters produce a higher quality roast than very large drum roasters?

I guess you never know until you run trials and blind tests, perhaps even participate in competitions, follow scientific evaluative protocl...it's a rabbit hole.

While I would caution straight-up conclusions like your last sentence... , I would further philosophize that small batch roasting (i.e., 227g - 1kg drums) and large batch roasting are different genres altogether. What I mean to say is, what's to gain when the highest practical quality of a product can't be produced at a medium-large scale? So roasting companies make do with 10kg roasters and start from there, regardless if the product could ever be made better in a Huky or a sample roaster.

But anyway, the research direction is leaning towards convection-focused roasting -- if you look at innovators such as Loring, Diedrich, Neuhaus. If this is where the trend lies, then, concerns about conductive heating and drum proportionality will become moot, academic, buried under environmental considerations, and then forgotten (like pan roasting).

As a personal answer, I would suggest to not worry about lack of conductive heating in larger roasters. It's just one face of a multi-sided die. Sincerely, a 2kg-roaster=owner-and-future-10kg-owner.