Fuller

Concise Bible Dictionary:

The word kabas simply implies “to wash,” as it is often translated, and would include “bleaching.” The coming of the Lord is compared to a “refiner's fire, and like fullers' soap,” when the dross and dirt will be cleared away (Mal. 3:22But who may abide the day of his coming? and who shall stand when he appeareth? for he is like a refiner's fire, and like fullers' soap: (Malachi 3:2)). At the transfiguration the clothing of the Lord became so white that it exceeded the whiteness produced by any fuller on earth (Mark 9:33And his raiment became shining, exceeding white as snow; so as no fuller on earth can white them. (Mark 9:3)). It was a reflection of heavenly glory.

Strong’s Dictionary of Greek Words:

Greek:
γναφεύς
Transliteration:
gnapheus
Phonic:
gnaf-yuce’
Meaning:
by variation for a derivative from κνάπτω (to tease cloth); a cloth-dresser
KJV Usage:
fuller

From Manners and Customs of the Bible:

The precise character of all the articles used by the ancient fullers is unknown. They had mineral alkali in niter, to which reference is made in Proverbs 25:2020As he that taketh away a garment in cold weather, and as vinegar upon nitre, so is he that singeth songs to an heavy heart. (Proverbs 25:20) and Jeremiah 2:2222For though thou wash thee with nitre, and take thee much soap, yet thine iniquity is marked before me, saith the Lord God. (Jeremiah 2:22). They obtained vegetable alkali, as the Arabs do at the present time, from the ashes of some plants and from the juices of others.
They likewise used, for cleansing their cloth, urine and chalk, and bean-meal mixed with water.
The cloths are thought to have been first trodden by the feet. They were also rubbed with the knuckles. A subsequent operation probably consisted in rubbing the cloth on an inclined plane, after the manner still followed in the East, and one which was common among the ancient Egyptians.