Fold the paper filter leaving the triple side facing the Chemex outlet. This is important to prevent the filter from collapsing in the container when it gets wet.
Rinse and preheat:
Rinse the filter with plenty of hot water to help “seal” it against the glass and remove the papery taste — it also preheats your Chemex. Discard this rinse water (you don’t need to take out the filter to pour out your water) and place your Chemex on a kitchen scale (optional).
Grind the coffee or add the ground coffee:
If you are grinding your fresh coffee beans, adjust your coffee grinder to a medium-coarse grind, slightly thicker than conventional pour-over methods. Chemex paper filters are designed with a thickness and shape that can restrict the flow of water through the coffee grounds, so this medium-coarse grind size will keep things flowing.
Blooming the coffee:
Grab your hot water, making sure your temperature is close to 94 degrees Celsius. Start pouring your water in a slow circular motion until the water level reaches about a finger below the upper edge of the filter. When the level drops about a finger (you don't want to see the top of the coffee bed while brewing), pour again and repeat as needed until you reach 300g of water.
Remove your filter and enjoy:
Keep an eye on the coffee while the water drips, and when you start to see the coffee grounds, remove the Chemex filter and put it in the sink or other drip container to drain (the last few drops of water may be a little bitter). The timer should read between 3:00 to 4:00 minutes. If the water is taking too long to drip through, try pouring faster or or grinding a little coarser next time. If it’s going through too quickly, pour slower or grind finer.
Enjoy your coffee!