Roasting Sundays & Shipping Mondays

Our Seismogragh explained - Roast color.


We have some good news for you!

One of the most frequently asked questions we get at Tectonic Coffee is how light or how dark do we roast? We have heard you loud and clear and have answered you individually now for many months. Well, we have some good news for you. 

We have now added a seismograph (get it? Tectonic Coffee, Tectonic plates, earthquakes, seismograph?) to each of our coffee offerings. This graph now depicts how light or how dark coffee is? 

You see it is a little hard to communicate roast color to the masses with just light, medium, or dark roasts and even using fancy words like “Full City”! We all have our own interpretation of roast color and the terms aforementioned but they are very limiting in a big way which we will explain later in this video. 

How does it work I hear you ask, well thanks for asking? 

At Tectonic we have a device by Madison Instruments called a Javaliytics which is a spectrometer that uses near-infrared light reflected from the coffee to determine the degree of roast. 

It then gives us a numerical number on the Gourmet Coffee Scale that has been widely used by the Specialty Coffee Association as a means to communicate roast color. 

We use this instrument on every single batch of coffee we roast by grinding a small amount of coffee once it has cooled, place it on the petri dish, and run the test. 

Fun Fact -  The Gourmet scale which we use to communicate roast color was invented by a gentleman by the name of Carl Staub using a device called an Agtron. You see many moons ago Carl, the inventor came up with an idea on how to measure the color of McDonald’s French fries so each franchisee could fry their French Frys the same color. He made a small fortune from this product back in the day and was left wondering what else could his device be used for???

French Fries

He approached a fledgling Specialty Coffee Industry and together they sent out a request to 100 roasting companies to send to him their lightest and darkest roasts. After a lot of testing, they produced not one but two different scales for us to work on. The commercial scale and the gourmet scale, which we use at Tectonic. 

Back to Tectonic 

The scale or in our case the seismograph we now have is very easy to use. The higher the number the lighter the roast and the lower the number the darker the roast. Remember when I said using words to describe the roast color is very limiting it is because the scale ranges from 0 through to the 100 and each number also has a decimal place! So we have 1000’s of numbers to describe the color of roast and light medium and dark just do not cut it. Get it?

For our sake, we have a scale ranging from 85 at the lightest because any higher than that in our opinion you start to get coffees that have hints of lemongrass in it (to light = roast defect). All the way down to 55 which is very close to the second crack…


Second Crack???

No you dirty birds that is not a reference to what is down under if you know what we are saying ;-) 

What is second crack then we hear you ask?

Well, we cannot talk about second crack without first talking about first crack! That’s right... First crack...

So green coffee or unroasted coffee lands in our warehouse in 132 to 152 lbs sacks and the green “seeds” that are contained with the sacks usually contain around 12% moisture give or take. So when we take this raw coffee and chuck it into the roaster at temperatures of 400 degrees or more that moisture over a period of time starts to leave the “seed” or coffee bean as the temperature of the bean produces steam. 

We like to imagine that for every part of the moisture that is evaporated out of the bean there is a part that stays stuck within. As the temperature of the roaster and the bean increases that part of moisture that is stuck within the bean becomes superheated and turns into a gas/ steam. Pyrolysis of the cellular structure occurs and an audible pop or crack occurs somewhere around 390 degrees plus or minus 5 degrees. 

Think of popcorn as an even more dramatic example of first crack, from corn kernel to actual popcorn that we can eat. #yum

This milestone in the coffee roasting cycle is so important to us roasters that typically we track first crack from the moment of it being audible, all the way through to the end of the roast, which we call the development time ratio. 

Now if we keep roasting we are now making the coffee bean darker by the advent of carbolic rings on the cellular structure of the bean. The coffee beans become even more porous and brittle that further Pyrolysis occurs as the residual oils in the coffee start to boil and a second audible popping occurs which we then call 2nd crack. 

Ever seen oily coffee beans? Well, now you know why there are sometimes oils on coffee, especially dark roast coffee. 

So on our graph 55 is as dark as we roast but it is not considered as dark as some coffees which venture well into second crack. 

Over time you, like us will actually be able to correlate taste to a numerical value, we are being incredibly transparent by using our actual data and the roast values we give you. 

We really hope that this helps you on your journey through specialty coffee and Tectonic Coffee. 

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