To clean Freetii unscrew the mug and hand wash it with a soft sponge. The filter is easy to access and clean once when the mug is dismantled.
Will my tea go bitter from the continuous steeping?
Freetii is designed for herbal tea rather than traditional green/black tea, almost all herbal teas won't go bitter from continuous steeping.
Will I burn my hand on the upper part of the mug?
No, the upper part is still insulated enough that you will not burn your hand. The upper portion will warm your hand whereas the lower portion will not because of the woods natural insulating properties.
Can I leave the pestle and knife in there with the tea?
Yes you could if you wanted to. We have removed all crevices from the pestle and knife so that the utensils stay hygienic. They don't take up much volume either (12mL).