Microwaves in natural stone resin treatment plants

For resin treatment with epoxy systems curing is currently carried out in static multiple tier ovens with forced air circulation (approximately 50°C), with slab holding time in the oven of around 80 minutes. In general, following oven curing the customary 24 hour period is allowed to elapse before proceeding with the polishing stage.

Recently, technological evolution has made it possible to positively consider also the use of curing microwave systems.

That's why the Breton Research Centre has been performing detailed studies to assess the capabilities and efficacy of using microwaves to accelerate resin hardening.

It should be emphasised that microwave curing ovens are rather different from normal ovens in that the former are complex, carefully studied and calibrated systems that combine microwave radiation with hot air convection heating.

During the research project we used various types of commercial resins: normal epoxy systems and "specific" epoxy systems designed for microwave curing.

The test results showed that microwave curing epoxy resins are highly reactive and display greater receptivity to microwave radiation. It was found that the combined microwave/hot air system effectively accelerates heating and successive hardening of the resin.

The annexed graph shows the exothermic reaction curve during hardening of two epoxy resins at 50°C, one of which is a normal resin and the other a microwave curing resin.