Electrodeposition of nickel

Nickel plating baths are improved by adding as brightening agent compounds containing the groups -Br-C=C-Br, or -Br2-C-C-Br2-, especially alcohols, poly-alcohols, or ether alcohols. Examples include, 2:3 dibromo-2-butene, 1, 4 diol, 2:3 dibromo-1-hydroxyethoxy-2-propene, and the product obtained by reacting butyne 1, 4-diol with ethylene oxide and bromine, which compounds have the formula:- in which R1, R2 are hydrogen or methyl, and R3 R4 are hydrogen, methyl or chloromethyl. The central double bond -CBr=C-Br may be replaced by - CBr2-CBr2-. Preferably there is also present a sulphonated compound e.g. vinyl sulphuric acid, sodium alkyl sulphonate, p-chlorbenzene sulphuric acid, nickel benzene sulphonate, sodium phenyl ethylene sulphonate, aromatic sulphinic acids-amides, or-imides, poly nuclear sulphonates or thiophene sulphoric acid or its salts with Na, Mg, and Ni. A table of tests is given showing results with and without the additions to a nickel plating bath.