Butanox® LPT-IN is a methyl ethyl ketone peroxide (MEKP) for the curing of unsaturated polyester resins in the presence of a cobalt accelerator at room and elevated temperatures. Butanox® LPT-IN gives in comparison with most other ketone peroxides a significantly longer gel time and is therefore particularly suitable for those applications where a long gel time or production time is required, for instance in the production of large parts and in filament winding.Also in areas with high ambient temperatures Butanox® LPT-IN is of particular interest. Butanox® LPT-IN is especially recommended for the cure of vinyl ester resins. This MEKP formulation gives less “foaming” than standard MEKP’s. Practical experience throughout many years has proven that by the guaranteed low water content and the absence of polar compounds, Butanox® LPT-IN is very suitable in GRP products for e.g. marine applications. The low hydrogen peroxide content of Butanox® LPT-IN makes this peroxide very suitable for the cure of those gelcoats, which tend to microporosity caused by the decomposition of the hydrogen peroxide.