Knowing how much catalyst to use on your project can be a little tricky if you are not working with composite materials on a daily basis. This helpful guide will offer an insight into the factors which can effect cure times. Catalyst (Organic Peroxide) is added to Polyster Resins, Topcoats, Gelcoats and Bonding Pastes so that the material you are using will cure.
By changing the amount of catalyst you have added to your base material you can control the amount of working time you have with your project. Very straight forward laminating may not need an extended working time so you can use more catalyst to reduce cure times. For more complex projects where you would like more working time to achieve the required result you may want to use much less catalyst in order to fully extend your cure times.
Mixing Ratios
The mixing ratio is calculated by weight. Catalyst is mixed between 1% and 4% of the base material. For example……
Obviously you will have much more working time when using 1% catalyst compared to adding 4% catalyst under the same working conditions. There are however several factors that can effect working time. Ambient temperature plays a crucial part in effecting working temperature.
The warmer it becomes the less catalyst you will need to maintain good working times. In mid summer it is common to use only 1% catalyst as the ambient temperature combined with the addition of catalyst can “Kick” the cure. This means you have very little working time and need to make sure you are not over extending yourself. Installers need to be aware that there will be limited time to perform the task in hand. Working in the cool of early morning in these circumstances can prove very helpful!
Another thing to bear in mind is that direct sunlight can help “kick” the cure so when working outside in sunny conditions this also needs to be factored in to your desired working times. A substrate which has been in the sun all day will also carry ambiant heat and laminating on a surface which has been exposed to sunlight, heat or both will also accerlarate the time taken for the project to cure and can decrease working times significantly!
In mid winter your projects may need as much help as possible in order to cure! Working times will be fully extended and the installer will want to encourage each project to actually cure. Using 4% catalyst in the warmest part of the day would facilitate a cure. NB - Please never use more than 4% catalyst!
In Spring and Autumn working with a standard 2% catalyst would probably be about right. In a controlled indoor environement with a working temperature of anywhere from 16 to 22 degress it is also common to use 2% catalyst.
Factors Effecting Working Times
Summer Catalyst
Summer Catalyst is designed to slow the curing times and give an extended working time when conditions are very warm. This would be especially helpful when working on a Fibreglass Flat Roof where working times are crucial on any large surface area.
Winter Catalyst
Winter Catalyst is designed to be used in much lower temperatures where standard catalyst will struggle to cure your project in good time. This catalyst will ensure that the cure takes place in good time and reduces the working time from standard catalyst considerably.
The following Guide shows how much Catalyst you will use for various amounts of Resin, Topcoat and Gelcoat.