Method for forming a sieve material having low internal stress and sieve material so obtained

Claim 1

Method for forming a sieve material comprising thickening a previously formed, electrically conducting sieve skeleton by metal deposition in an electrolysis bath until the final thickness of the sieve material has been reached, wherein the bath includes one or more chemical brightening compounds in the bath having the properties of both a first-class and a second-class brightening agent, said compound being present in the bath in such concentration and being added to the bath in such proportionality to the Ah (Ampere hour) load that the internal stress of the finished sieve material with respect to a material formed using one or more conventionally used Class II brightener is reduced wherein the brightener is a sulphur-containing organic compound having at least one unsaturated bond in the molecule and is used in an initial concentration of at least 0.25 mmol/liter of bath liquid and an addition rate of at least 1 mol/10,000 Ah load; and wherein one or more of the following conditions apply during thickening: during at least part the time needed for thickening, bath liquid flow is brought about through the perforations of the sieve skeleton in a direction which is perpendicular to the sieve skeleton, the thickening is carried out using a pulsating current which comprises pulse current periods (T) and current-free or reverse current periods (T'), where T and T' are set, independently of each other between 0 and 9900 msec.