Leaded lights are given a waterproof seal by squeezing a special putty, known as ‘leaded light cement,’ between the lead and glass.
Rhoddir sêl sy'n dal dŵr ar ffenestri plwm drwy wasgu pyti arbennig, a elwir yn 'sment plwm ysgafn', rhwng y plwm a'r gwydr.