Resin Surfacing Products

Using Catalyst in Resin Bound Stone

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.

Resin bound catalyst: the key to reducing curing times

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.

What is the right amount of catalyst?

Pinpointing the correct amount of catalyst can be challenging and varies between manufacturers and resin formulations. Our recommendation is to always consult the supplier or manufacturer. It's also wise to stick with the same manufacturer for both resin binder and accelerator to ensure compatibility and avoid adverse effects.

For instance, if you use PERMABOUND resin, opt for PERMABOUND catalyst, BoundFast. If you are using our PermaBound UVR resin, refer to the table below for an indication of how much catalyst should be used to ensure the resin cures within the typical timeframe. If you're using a different product, contact the supplier or the manufacturer for guidance on the specific materials.

Air Temp (°C) PermaBound UVR 6.5kg PermaBound UVR 7kg PermaBound UVR+ 7.5kg
>20.0°C None None None
17.5°C 4.4ml per kit 4.8ml per kit 5.1ml per kit
15.0°C 9.8ml per kit 10.6ml per kit 11.3ml per kit
12.5°C 16.6ml per kit 17.9ml per kit 19.2ml per kit
10.0°C 29.3ml per kit 31.6ml per kit 33.8ml per kit

How to mix catalyst with resin?

The BoundFast catalyst comes in a 200ml bottle with a 5ml cap. The cap can provide approximate measurements but we recommend using a 1ml syringe for precise control over the amount added to the mix. Although it may take a bit more time than a rough 'capful' measurement, it guarantees consistency in curing times.

Ensure the syringe is clean and dry before drawing up 1ml at a time and inject the catalyst slowly into the Part A component of your resin binder. Repeat the process until you reach the required dosage based on the temperature table provided above. Mix the two resin components (parts A & B) according to the manufacturer's instructions.

If you have any questions regarding BoundFast resin catalyst or any of the other products in our range, please do not hesitate to contact us.

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