Open the Chemex filter so that there are 3 plies on one side and one ply on the other. Place the filter in the Chemex with the 3 ply side facing the spout.
Rinse your filter with near boiling water so that the filter seals on to the walls of the Chemex. Drain from the single ply side.
Grind 40 grams of coffee on a medium coarse setting. Transfer the ground coffee into the Chemex. Place the Chemex on your scale and zero your scale.
Start the timer. Right off of boil, pour in 80 grams of water to bloom the ground coffee. Stir the bloom and wait until your timer reaches 30 seconds.
Off of boiling, spiral pour (to evenly saturate the coffee bed) to 340 grams over time until the timer reads 1 minute.
Bring the pour to the center and continue the pour rate so that the total weight is 680 grams at 2 minutes.
Stir gently to remove grinds from the Chemex walls. The remaining water in the bed should draw down by 4:30 minutes.
Dispose of filter and swirl.