I'm sure you get a lot of variations of this question daily and I want to give Peter the benefit of the doubt.

I interpret the core of the question to be "how long will it take me to reach the skill level necessary to roast coffee good enough that customers will want to buy it over and over again?"

Going deeper the question is a bit flawed as there are "hidden variables" masquerading as "assumed constants": "Skill level", "good coffee" and "customers". There isn't a universal skill level that a roaster must reach before they can be a commercial roaster, "good" coffee is extremely subjective, and knowing what your customers value in their coffee is crucial. So to solve for those hidden variables, I'd approach the question from a more customer focused angle: "What coffees are my future customers currently buying over and over again and why?"

I'd want to know their top 3-5 values in order. Things like:

• Price
• Roast Level
• Consistency
• Quality
• Certifications (Fair Trade, Organic, etc.)
• Uniqueness
• Something else

This really helps to unlock everything. Since roasting darker is easier than roasting light, it's possible to start commercially roasting with less skill if your customer base wants really dark coffee. If your customer base wants lighter roasted coffees or more experimental processing methods you'd need more skill start roasting commercially.

Since you only have 2 hours a day, I'd recommend learning as much as you can about your customer base and the roasting process in general before actually roasting. Some great resources for learning about coffee roasting include:

YouTube:

• Mill City Roaster's "Roaster School - Season 1" playlist
• Virtual Coffee Lab - Home Coffee Roaster

Books:

• "Modulating the Flavor Profile of Coffee" by Rob Hoos
• "The Coffee Roasters Companion" book Scott Rao
• "Exploring the Dark Side" by Rob Hoos (If your customers like dark coffee)

Then I'd take the Mill City Roasting 101 class (either in person or online).

Anecdotally, in my limited personal experience I've found learning to roast isn't a linear process. I started on a Fresh Roast which was great in learning some of the basics of roasting. It took me about 25 roasts to get comfortable with basic concepts. It took me to about 50 before I felt comfortable being consistent from batch to batch. Making the leap to a commercial roaster, the science is the same but the controls are different. It felt like I went from driving a golf cart to high end sports car with a sensitive manual transmission. I'm about 130 roasts in on my MCR roaster and feel like I'm starting to get the basics of it. I think I'll need another 200 roasts or so before I feel comfortable with a solid medium roast, and another 200-500 roasts after that to start to understand light roasts.

Good answer. I'll pass it on.

My feeling is most people get to a base level of competency sufficient to produce salable coffee by the end of class.

It's normally about 100 to 150 roasts to learn to drive the machine without an excess of thought. Then another 100 to 150 roasts to convince yourself you know how to do this. Followed by another decade overcoming imposter syndrome because 1 in 15 coffees routinely throw you a curve.

Late to the topic but for future forum lurkers, here's my take...

I have taught guitar to people over the years, and learned from other teachers, and this kind of question is the most common for new learners ("How long will it take me to learn to play Wonderwall?") or those wanting to up their skills to another tier ("How long will it take me to shred like Eddie Van Halen?").

My response is always pretty similar: How much time do you have to practice, and what is your motivation?

Roasting skill level is pretty much the same equation. If you're motivated by sales (especially if they are already starting to roll in) and/or a true appreciation for the art/science/magic of the trade, then you're in a good spot to move your learning along. Time is more difficult because you likely have less control over that finite resource versus motivation. If it's a side gig you can only work on for a few hours a week, it will take more time overall to become proficient due to the start/stop/start/stop nature of your learning curve. I will say, 2 hours a day is a good learning intensity, but it also may be an unrealistic goal if your motivation is mostly monetary and you hate math/science. Or you may find you're up all night because you're fascinated by the process.

Think of it like electricity - your motivation is the amperage that pushes the voltage of your time. They will equal a certain amount of wattage (level of proficiency) in total.

This applies both to learning the physical process of operating and maintaining your equipment, as well as the process of planning, observation, evaluation and adjustment that comes with roasting the actual coffee to it's peak capability.

Last thought - mastery is a tricky word, because it is essentially a nearly unreachable goal (we're all always trying to do better/different/new things as we increase our proficiency). But to a similar question of "how long until I'm fully confident and knowledgeable to be consistently roasting good coffee?"....I think you can get there with 100 hours of roasting.

You can picture learning/proficiency just like bean temperature a roast curve - it initially has a lot of activity over a short period of time at the very beginning, then you are mostly rolling along with a gradual increase of knowledge over time. Our learning curves all start in different places and have different variabilities, but the general nature of the knowledge flow over time looks very similar.