Chasentoshi refers to a series of movements where hot or cold water is poured in a tea bowl, and the bristles of chasen are swayed in it and moved in and out of it, before and after making the tea.
点前で茶を点てる前後に、茶碗に湯または水を張って穂先を振ったり茶筅を上げ下げしたりする所作を茶筅通しと呼ぶ。