Further useful thickeners suitable for use as component (d) are polysaccharides such as carboxymethyl cellulose, methyl cellulose, methyl- or ethylhydroxyethyl cellulose, carob seed gum ether or starch ethers as well as alginates, polyethylene glycols, polyvinylpyrrolidones, polyvinyl alcohols or also finely particulate silicic acid preferably having a specific surface area of 50 to 380 m2 /g, and