Abstract: A method of inhibiting scale formation by salts of calcium, magnesium, barium and strontium from aqueous solutions, by adding to the aqueous solution a minor proportion of a product comprising a telomer of formula I: ##STR1## or a salt thereof, wherein X is CO.sub.2 H when Y is H and vice versa, B and B' are each hydrogen or B is CH.sub.3 when B' is H or vice versa, m is an integer from 2 to 100 and n is 0 or 1, R is an hydroxyl group, alkyl having from 1-22 carbon atoms substituted by one or more carboxyl groups.

Abstract: Oxo-polycarboxylic acids act as set control agents, preferably as set retarders for plasters. Examples of usable acids are 2,2,6,6-tetra(.beta.-carboxyethyl)cyclohexanone, 2,2-di(.beta.-carboxyethyl)-3,5,5-trimethylcyclohexanone or 3-acetyl-3(.beta.-carboxyethyl)-pimelic acid. Also the salts of these acids are usable. The set control agents are added to the plaster in amounts of 5 to 5000 ppm.

Abstract: A method of inhibiting the precipitation of scale-forming salts of calcium, magnesium, barium and strontium from aqueous systems comprising adding to the aqueous system a telomeric compound of the formula: ##STR1## or salts thereof, wherein R.sup.11 is hydrogen, methyl or ethyl, R is hydrogen, 1-18C alkyl, 5-12C cycloalkyl, aryl, aralkyl, a residue of formula: ##STR2## wherein R.sup.11 has its previous significance and the sum of n + m is an integer of at most 100, or a residue --OX wherein X is hydrogen or 1-4C alkyl, and R.sup.1 is a residue --OX wherein X has its previous significance.