If your coffee grounds are too fine, your coffee may become over-extracted. Over-extraction will result in an overly bitter and sometimes even burned taste. If your grind is too coarse, the flavor compounds in the coffee won’t have the chance to be fully released during the brew cycle. The result will be under-extracted coffee, which will taste weak and flavorless. Under-extraction can also occur if your grind is inconsistent in size.
Not only does incorrect grind size result in an underwhelming brew, it can also be the culprit of some brewing frustrations. Coffee that is ground too fine can cause your brew basket to overflow because the water is moving too slowly through the dense grounds. With overly coarse grounds, the water may run through too quickly and not saturate the entire basket.
It’s easy to mistake both over- and under-extraction for a poor coffee roast. If you consistently have difficulty getting satisfying results, we suggest adjusting the coarseness of your grind. When brewing with a Moccamaster, the grind size should be medium-coarse, like sea salt or rough sand.
Most pre-ground coffee purchased in the supermarket is ground too finely for optimal performance on the Moccamaster. If you have been enjoying a pre-ground coffee on a different machine and find that it doesn’t taste the same when brewed on a Moccamaster, you are most likely getting an over-extracted brew. We recommend grinding your coffee using the “pour-over” setting or having it ground for you at a roastery or café, but if you prefer to use pre-packaged ground coffee and you find it too fine, experiment with using less coffee.