Ib txwm siv cov yas cutlery, feem ntau siv rau kev noj mov thiab kev sib sau ua ke, muaj kev cuam tshuam rau ib puag ncig. Nws yog tsim los ntawm roj av, ib qho khoom siv tsis tau txuas ntxiv dua tshiab, thiab siv sijhawm ntau pua xyoo los decompose hauv qhov chaw pov tseg, ua rau muaj kuab paug yas.