as title asks…
Cumyl Hydro Peroxide.
Some brand names are Trigonox 239, Andonox CHM-50 or CHM-30 (probably also available in USA)
You are probably working with vinylester? It is the standard catalyst for many vinylesters.
Yeah, that was the recomended catalyst for an infusion vinyl-ester resin. Thank you Herman, your full of useful product info 
HaHa no kidding. Herman is like a Human composite catalog. 
I just finished our 180 page composite catalog. In which some 30 different types of peroxides (catalyst). also I had a nice course from our supplier of peroxides.
Next will be our website, but I will post a thread on that (non commercial, as we mostly ship to NL and BE, and some things European)
What kind of resin system are you using it on? Just curious… I’m using Hydrex 100LV for infusion. I catalyze with 1.5% MEKP-9 or MCP slow catalyst.
If you do, stick with that, as a CHP catalyst like the CHM-50 will give much higher peak exotherm (can be good in thin laminates)
If you are in for a change you could request SHP-90 catalyst (if I recall correctly), also from Norac Andos, which keeps the viscosity down for a longer period of time.
With the MCP you might notice some foaming just after mixing, but I do not feel that has much influence on laminate quality, if you leave the vinylester to settle for 5 minutes.
SHP-90… Does anybody know how that will work with Hydrex-100LV? I get 10 - 15 min gel time with 1.5% MEKP-9. How about with the SHP-90? I’d like a longer gel time, but once it gels it kicks fast.
Hydrex-100LV is this resin made for vacuum infuion,RTM or injection molding only, that is a real quick gel time for vacuum infusion resin.
^ It works great to make molds :). Or should I stop? I’ve made half a dozen molds with this stuff and I believe its an amazing mold making product. It withstands good heat, and is strong.
And yes, 10 -15 min is very quick. In the past 90 days alone I must have had half a dozen parts not fully infuse because of so.
For mold making I have Nord Composites RM6000, which is a compensated vinylester:
As soon as the resin shrinks due to cure, a polymer expands, thus the net shrinkage is 0%
I will look up my table for the different peroxides. MEKP-9 is fast indeed. It is a AAP/MEKP blend as far as I recall, making for fast geltimes and very fast cure rates.
-just checked Andos.se website, but that is useless.
MEKP-9: a slowe version is MEKP-9H
even slower is MEKP-925H, some 3 times as slow as MEKP-9.
The peroxide for keeping viscosity low is HDP-75. Excellent wetting of the fiber, approx same results as MCP peroxide, but slightly higher peak exotherm. (although still very low).
it’s only avalible in California 50/50 mix of doughnuts and coffee