Microporous

Techniseal's product guide says its paver protectors are microporous, which means they let moisture out. ICPI's Tech Spec 5 uses a different word for the same property: among the conditions under which a sealer may whiten, it lists a sealer that "is not breathable, i.e., does not allow moisture to move through to the surface of the paver and evaporate." SEK-Surebond's SB-1300 data sheet uses breathable as well, saying the product "will not trap naturally occurring moisture and efflorescence."

One institute and two sealer makers, then, use two words for one property: microporous is Techniseal's, breathable is ICPI's and SEK-Surebond's. ICPI applies the same idea to a penetrating product. A silane and siloxane sealer, it says, creates a hydrophobic barrier that keeps moisture from entering while allowing the concrete to "breathe" or release water vapor.

The property can be lost. Techniseal's guide says that if too much protector is applied too often it creates a build-up, and the product loses its microporosity, which could lead to whitening and peeling of the film. SEK-Surebond's SB-1300 sheet makes the matching point in its own word: excessive applications may decrease breathability. The ASCC's guide for decorative concrete sealers, written about a different surface, warns that over-application can cause bubbling, cracking and whitening, and that a water based sealer placed too thick whitens once it dries and can only be repaired by mechanical grinding or blasting.

Whether a sealer that lets moisture out also keeps water from getting in is answered on whether sealing makes pavers waterproof, and the wider problem of stacking coats is taken up on whether pavers can be resealed too often. ICPI's full list of whitening conditions, of which a sealer that is not breathable is one, sits under why sealed pavers turn white, and the general term has its own entry under sealer.

Breathability is also the reason SEK-Surebond gives for applying SB-1300 immediately after installation, one of several positions set out on who decides how soon new pavers can be sealed. Whether a given product is microporous or breathable is read from its own data sheet.