Film-forming sealer

Film-forming is the sealer makers' word for where a cured product sits: on the face of the paver or slab, as a film.

Techniseal's Product Guide (document 341-418, revision 02/24) lists its Wet Look and Satin Look Protectors as forming “an ultra-durable protective film,” and the Wet Look (WL1-2) Protector's own data sheet describes it as “Made of acrylic and plasticizers.” Euclid Chemical, writing about poured concrete, treats the word as a category: where a color change after sealing is a concern, it says to use “a penetrating water repellent sealer” or to test “a film-forming sealer” on a small area first.

Inside the category, ICPI's Tech Spec 5 (revised February 2018) names the chemistries. Acrylic sealers, it says, “enhance paver colors well and create a gloss on the surface,” and polyurethanes “produce a high gloss and enhance the color of pavers,” the look the makers sell as a wet look. The silanes and siloxanes ICPI describes form a film too, but inside the concrete: both become a polymer “curing as a film in the capillaries of the concrete,” the other family, defined under penetrating sealer.

A film is not always sold as a shine: Techniseal's Natural Look (NS) Protector is “Made of acrylic” and “forms a protective film” while preserving the original look of pavers, which is why a natural-look paver sealer can come from either family.

A film-forming sealer's surface film is where ICPI's credits for the glossy chemistries show, and where the makers' cautions start.

Stain resistance is among ICPI's credits to acrylics: they “provide good stain resistance,” and sealers that keep stains out “are useful around trash receptacles, fast food restaurants, driveways, other areas subject to stains, and where oil drippings are not wanted.” A Naples paver driveway is one of the surfaces on that list; how its needs weigh against a pool deck's is argued under whether driveway and pool pavers need a different sealer. ICPI adds that acrylic durability “depends on traffic, the quality of the acrylic and the percentage of solids content.” A slip-resistant texture can also be carried in the film, the subject of the answer on an anti-slip additive for a sealed pool deck.

Renewal is where the two glossy chemistries part ways in ICPI's account. Pavers with worn acrylics, it says, “can be easily cleaned and resealed without the use of extremely hazardous materials,” while “Urethanes cannot be rejuvenated simply by re-coating.” Each chemistry has its own entry, at acrylic and at urethane.

A film can also hold something beneath it. Techniseal's NS data sheet notes that “Any new concrete product has the potential to produce efflorescence” and adds: “This Protector, like any film-forming coating, carries a small risk of trapping efflorescence beneath its film.” That caution sits behind the makers' disagreement over how soon new pavers can be sealed. The same maker says too much product applied too often “could lead to the whitening and peeling of the film on the surface,” a cause laid out beside others under paver sealer peeling and pavers resealed too often.