Why does my tea still taste bitter when the infusion is stopped by the plunger?

This might be because you’ve put too little or too much tea to start with. Too little, and the sealed chamber at the bottom cap would have too much residual water that will keep brewing the sealed leaves at the bottom, and the subsequent infusion may be bitter. Too much, then the plunger may not seal properly and may even compress on the tea leaves and release bitter flavors. We recommend dosing your ECLIPSE Travel Press with 4 to 7 grams (0.14 to 0.25 oz) of loose-leaf tea for best results.