Since conventional UV light curing reaches its limits with very large wall thicknesses of the lining tube (> 7 mm or more depending on the manufacturer), combination or hybrid curing is used here.

Here, the ongoing UV light curing activates the thermal curing. Once the UV light has heated the lining tube to approx. 60 °C, the thermoreactive peroxides activate the thermal reaction. Both curing mechanisms lead to the final polymerization of the resin matrix.

With hybrid curing, glass fiber liners with practically unlimited wall thickness can be installed without losing the other advantages of the process, especially its speed. For larger wall thicknesses (especially with ovoid cross-sections), exclusive UV light curing becomes potentially uneconomical or even risky due to the reduced speed of the UV Light chain. This is because the lower the speed, the higher the risk that the internal membrane will start to burn or stick and then cannot be pulled out.