Penetrating sealer

ICPI's Tech Spec 5 (revised February 2018) describes the penetrating family through silanes and siloxanes, and its account starts with where the product goes.

“Silanes and siloxanes penetrate concrete well,” it says. Silanes, the simpler form, begin to link up with other silanes when exposed to moisture, siloxanes do the same, and “Both chemicals become a polymer, curing as a film in the capillaries of the concrete.” The film is there, but inside the paver rather than on its face, and ICPI adds that they “initially enhance colors and produce a flat, no-gloss finish on the paver surface.” The two molecules and how they differ are the business of the silane and siloxane entry.

Euclid Chemical, writing about concrete sealers, states the same boundary from the outside: “Silane and siloxane water repellents do not form a film on the concrete surface.” The acrylics and urethanes that do form one make up its counterpart, film-forming sealer.

Makers' descriptions use the word more broadly than that. Techniseal's Product Guide labels its (iN) Natural Look Protector “Penetrating,” with a Matte finish, while Techniseal's Natural Look (NS) Protector, under a near-identical name, is a film-former, which is why the natural look entry treats the phrase as a finish and not a family. Seal 'n Lock's own guide calls Super-Wet-Look a “Two-Part, Water Based Pure Urethane Sealer” and says it “penetrates into the pavers,” yet ICPI credits polyurethanes with a high gloss. So the word is a starting point; the chemistry and finish on the product's own data sheet say which family it belongs to.

Two of ICPI's lines about silanes and siloxanes name settings a Naples paver surface can sit in: salt air and the edge of a pool.

The first is about chlorides: “Their ability to decrease intrusion of chloride materials provides additional protection of pavers subject to deicing salts or salt air.” That is ICPI's statement about a sealer family. It is not a finding that salt air damages pavers, or that a paver near the coast has to be sealed.

The second names the pool: “They are also useful around pool decks to minimize degradation from chlorine.” The line is written for concrete pavers; whether it carries over to stone is weighed in the answer on sealing outdoor travertine.

ICPI also marks where the family stops: “Silanes and siloxanes do not resist penetration of petroleum stains unless they have additives specifically for that purpose.”

ICPI's verb for what any sealer does to water is reduce, which stops short of calling a sealed paver waterproof. Whether a flat, penetrating finish keeps a pool deck cooler has no measurement behind it in the documents read for whether sealing makes a pool deck hotter underfoot. For a particular product and surface, ICPI sends the question to “the sealer manufacturer or supplier” before any sealer is used.