Hi, do food storage and prep items that will not be brought to the table require tovelling? I have read that a thermometer does not need it, but unsure if glass jar i have bought to blend cold foods in or to store food in require tovelling. thank you

Dishes which come in contact with food in its initial preparation stage, and the food needs further preparation [after using the dish], in order to prepare it for eating, such as a sifter, stainless steel rolling pin, dough dishes, Shechitah (slaughtering) knife - immerse without reciting a Brachah. Dishes which the food becomes edible during their use such as pots and pans – require immersion with a Brachah. (Shulchan Aruch and Rema Yoreh Deah 120, 5. Sefer Hakashrut of Rabbi Fuchs 4, 19 & notes). Dishes used to store food, if the food is always wrapped such as tea bags or wrapped candy – they do not require immersion. Dishes which contain food that is in direct contact with them, if the dish is used only for storing – it should be immersed without a Brachah. Storage dishes which are brought occasionally to the table, and people eat out of it - require immersion with a Brachah. (Sefer Hakashrut of Rabbi Fuchs 4, 20 & notes).