“…Moreover, in a humid environment, even an overnight period cannot assure perfect plug closure, because the dried silicate swells again under the action of ambient water and looses its tightness. Faster and more durable closures could be made by using alternative substances, such as epoxy glue [5], self-curing silicone rubber [6], or vinyl monomer (methyl methacrylate) polymerization induced by peroxides and UV light [7].…”