There’s no escaping the reality that installing resin bound stone is a job a seasonal job. Given that generally, polyurethane binders are sensitive to temperature and moisture, it’s almost inevitable that in the UK, from around the end of September, the number of suitable days for laying resin bound significantly decreases.
Resin bound stone binders are typically formulated with curing times based at a mild 20°C, providing an installer with a window of 30-60 minutes for spreading and troweling before it begins to become tacky and unworkable. As air temperatures drop below 20°C, the curing time of the resin component begins to extend.
When the ground and air temperatures are too cold, the reaction between part-A and part-B of the resin slows down. The lower the temperature, the slower the curing process becomes. If the surface curing process is too low, the resin binder becomes vulnerable to dew, condensation or rain collecting on top. Experienced resin workers or those who have attended resin bound training courses know that avoiding moisture is absolutely critical.
While we can’t control the weather, adjusting the mix can speed up curing times. Adding more gravel, sand, or resin doesn’t positively impact curing time, so a resin bound catalyst (also called an accelerator) can be added to help expedite the process.
In reality, adding a catalyst doesn’t make anything cure quicker than usual, it counteracts the slow curing time, allowing the mix to set within the normal timescale and avoiding long or overnight curing.
