each other where they are in mutual contact to form a mat this mat prevents direct contact between the peeler and the surface of the anode the electrodeposition of cobalt onto the tip of the peeler may still continue although probably at a restricted rate because the electrolyte paths near the tip of the peeler are restricted as a result of local compression of the mat at 8 however when the cathode is removed after a peeler has formed only a small amount of fibres from the mat are pulled away as they are incorporated in the peeler the mat is not however irreparably damaged and only a small loss of material occurs the anode baskets may be segmented ie may have a series of vertical compartments in addition to preventing damage by peelers the mats prevent the escape of impurities from the anodes in much the same way as conventional woven anode gaiters there is a significant difference in properties between conventional anode gaiters of the woven type and the mats as used according to the invention in order that woven gaiters restrain a significant proportion of the impurities contained within the anode they have necessarily a fine pore size.