However, the addition of resin to glass ionomers, improves properties significantly, allowing it to be more easily mixed and placed.[3] Resin-modified glass ionomers allow equal or higher fluoride release and there is evidence of higher retention, higher strength and lower solubility.[3] Resin-based glass ionomers have two setting reactions: an acid-base setting and a free-radical polymerisation. The free-radical polymerisation is the predominant mode of setting, as it occurs more rapidly than the acid-base setting, which is comparatively slower. Only the material properly activated by light will be optimally cured.