place or treat in a vat

the grapes are vatted for between 15 and 21 days and then aged in small barrels

a large tank or tub used to hold liquid, especially in industry

a vat of hot tar

a water-insoluble dye, such as indigo, that is applied to a fabric in a reducing bath which converts it to a soluble form, the colour being obtained on subsequent oxidation in the fabric fibres