JS Promoter D is a promoter which can be used to increase the reactivity of ketone peroxide/cobalt accelerator based cure systems in a wide variety of unsaturated polyester resins. Promotor D can effectively be used in standard ortho- and iso phthalic acid based polyester resins, Bisphenol A/fumarate resins and vinylester resins. Promotor D can, in vinyl resins, also be used to increase the reactivity of the cure system Trigonox 239/cobalt accelerator and Butanox LPT/ cobalt accelerator.Promotor D can be used in these resins as a substitute for the promoter N,N-Dimethylaniline. In comparison with N,N-Dimethylaniline Promotor D is a low toxic compound.It does not give a yellow to brown discoloration of the cured UP resin part as it is usually observed when aromatic amines are used as promoter.