Wonderful question, thanks for asking!

First, imagine a vessel full of sand. Next, imagine pouring water onto the sand. Now, watch the water flow.

What happens to the water if the sand is filled with large gritty pieces of sand or some rocks causing little pockets of air?

Answer: The water will move quicker through the sand. 

What would happen if the sand is fine and well packed together?

Answer: The water moves slower through the sand.

Now, we have our course sand, and fine sand water. Which do you think is the dirty water?

Answer: The water that spent more time traveling through the sand.

Extraction is all about time within the brew bed or the coffee bed; both are synonymous.

"So, Trevor. If my water sits in the coffee for a super long time, that means its good right?"

Nope. Nothing is ever that simple.

"Okay, Trevor, how do I control extraction?"

For today, let's focus on three easy contributing factors to yield a nice extraction:

1. Brewing Ratio
2. Grind Size
3. Water Temperature
4. Time

Brewing Ratio

Brewing ratio is a recipe we are using to craft whatever coffee beverage we want with our desired brewing vessel. For example, maybe we are using a V60 for a simple pour over. A brew ratio for this would look like 1:16, or 21.26 grams for a yield of 340.19 grams of water, or 12 oz. If we use too small of a coffee dose to yield the desired output, our coffee will end up tasting diluted. Too much of a coffee dose to the water output, will result it to be overly extracted, and will leave us with a bitter and hollow taste.

Grind Size

Every grinder is different, and no number system has any rhyme or reason. But don't let that overwhelm you. Let's revert our minds back to our sand and water analogy. Think of it like this: finer grinds equals more extraction, and coarser grinds equal less extraction. Sure, there are rules of thumb. If I'm making a 10-cup batch brew, my grounds should be a little coarser than a single cup pour over. The dose is higher, so the yield is higher. We need the water to not get choked down in the slurry (or brew bed), to cause any types of diminishing returns.

Water Temperature

This seems like an easy one. "Trevor, just let it boil, then use the water." Sure, you can totally do that, but you could be missing out on some really interesting finding held within your coffee if you lower that water temperature by a few degrees. 

Within the world of specialty coffee, light roast and high-density beans reign supreme. Well, to brew these coffees properly, we need to examine water as a real thing. The nature of roasting these coffees leaves plenty of density and sugars within the molecular structure of the seed walls. We need a certain brewing temperature to unlock the flavor hidden within those walls. Somewhere around 201-208°F is a prime spot to play when dealing with these types of coffees.

With that said, those who love the moody, more robust notes of a lingering dark roast, can rest easy knowing even cooler temperatures can still result in a well-extracted cup. This is because the darker a coffee is, those molecular structures break down, making the seed more soluble to work within the brew bed. So, the next time you stop by Sabbath, ask your barista if this is a light or dark roast!

Time

A longer brew time equals more extraction, and a shorter brew time equals less extraction. Drippers like, my personal favorite, the Clever Dripper, or the Aeropress, have a built-in time function. This is because you, as the brewer, decides when the coffee is removed from the brewing vessel. Something like a Kalita Wave or V60, time is determined by the liquid leaving the brewing vessel, stopping the extraction.

Listen, I know all of this seems overwhelming, but I hope you find a few of these simple charts helpful in your daily brewing. Also, don't be scared to try new things. My best advice is to buy a few pounds of the same coffee and play. Play with the main four variables and see how they react. Start with a simple brew ratio, then maybe increase or decrease the brewing time to see how the flavor changed. Keep a notebook. It's fun, trust me. Write down what you smell and taste. Make it an experience. Seriously, if you made it through this entire blog, you might as well start journaling about your coffee brewing experiences.