Crossword puzzle clue "like some lens coatings"

acting to stop a car window from fogging up

intended to prevent rust

sceptic, denying the possibility of knowledge

ARIL, an additional envelope, often fleshy, developed around the seed in certain plants (e.g. yew), also ARILLUS

ASH, to convert something into ash

DEW, to wet with condensed moisture, also DEAW

DYE, to change the colour of

EMULSION, a colloidal suspension of one liquid in another