Waterproofing - impervious to water - especially: covered or treated with a material (such as a solution of rubber) to prevent permeation by water ~ Merriam Webster
Tried and True - expression which describes a product or method that has already been used and has been found to be successful ~ Collins English Dictionary
One of the many great properties of epoxy resin – aside from the adhesion and filling attributes – is its ability to seal and form a waterproof (and anti-corrosive) layer of protection. Versatile epoxy resin is used in myriad residential, commercial and industrial applications – and is an instrumental material for homeowners, contractors and engineers to have on hand for repairs, maintenance and construction projects of all kinds.
“In fact, the applications for epoxy seem to only multiply with time, as the chemical agent is able to take on a wide variety of properties imbued in it by various industrial treatment processes, thanks to which epoxy resins can be very fast setting or extremely slow setting (or curing); they can be of the most solid rigidity, or they can be given a great degree of flexibility; they can be transparent or opaque or given a certain color," from 'The Benefits of Using Waterproof Epoxy Resin,' a resource for the construction industry & DIY-based projects.
“At home, epoxy resins have practically unlimited uses, and home owners will find that in a wide variety of home improvement projects epoxy will be one of the key ingredients to have around especially as it is a water repellent. First and foremost, think waterproofing: wherever there’s a leak to be plugged, there’s an epoxy resin to be applied. An example of such an application is when fixing a sink basin to the bottom of a kitchen countertop (made of wood, metal, stone, etc.). Thanks to the excellent bonding properties, the epoxy won’t have a problem fastening to either the material of the sink or the countertop, whether they are the same or different.”
Epoxy resin may be applied to waterproof and protect almost any substrate materials including plastics, masonry, concrete, wood, and metals. The polymer is used in diverse applications including marine and auto repair, industrial construction for bridges and other structures, high-technology fabrication for aerospace, aircraft and wind turbines, and of course, as an instrumental part of keeping our homes and offices maintained as an invaluable repair, project and craft material.