How many coats of sealer do pavers need?

ICPI's Tech Spec 5 never prescribes a coat count. What it describes instead is the method: application by hand roller for a small area, a powered roller or a low pressure sprayer for a larger one, with the sealer spread to stand in the chamfers, soak into the joints, and any excess pushed off to an unsealed area with a squeegee.

Its only lines on a second coat are conditional rather than numeric. “With some sealers that recommend two coats, the first coat is usually applied to saturation. A light second coat, if needed, can be applied for a glossy finish.” For water based sealers that do call for two, ICPI adds one more condition: “always apply the second coat while the first coat is still very tacky.” Neither line says which sealers recommend two; that answer sits with each product's own label.

Techniseal's WL1-2 Wet Look Protector is a single-coat application, with a second coat only on a never-sealed surface, once the surface “is dry to the touch”. Its Natural Look (NS) sheet applies a single coat: saturate the surface, then remove the excess with a roller before it dries.

SEK-Surebond's SB-1300 follows the same pattern from a different maker: it “is designed for a one-coat application but if desired an additional light spray coat can be applied only after the first coat has dried to the touch.” Three data sheets, three products, and none of them makes a second coat standard.

Seal 'n Lock's Super-Wet-Look, a two-part water based urethane sealer, is built the other way: it is a two-coat system by design, a diluted flood coat first, then a top coat once the sealer tacks. Extra coats may be applied for desired enhancement, and the guide notes a slip guard additive may be necessary with additional coats.

No document read ranks a two-coat system above a one-coat product; the count follows the chemistry and the application each maker designed. The wait between coats inside one application, tack on Seal 'n Lock's guide and dry to the touch on the one-coat sheets, is one sense of what the trade calls the recoat window.

Techniseal's product guide table lists a coat count by product row: one or two coats with about two hours between them for the Wet Look row, two coats applied wet on wet for the penetrating (iN) Natural Look row, one coat for the Satin Look row, and one or two coats with about four hours between them for the WA row. Techniseal labels those first three protectors Gloss, Matte and Satin; the finishes are defined under wet look, natural look and satin finish.

That guide table and the WL1-2 data sheet disagree on the Wet Look wait: the table prints about two hours between coats, while the data sheet puts the second coat once the surface is dry to the touch, about four hours. The condition to go by is the data sheet's, dry to the touch, and each hours figure stays with the document that prints it rather than being settled as one number.

The counts come with limits. SEK-Surebond's SB-1300 sheet, Techniseal's WL1-2 sheet and Seal 'n Lock's guide each print a warning about too much product beside their instructions, and the Decorative Concrete Council's guide, written for concrete sealers, calls the coverage rates on a product's label the best guideline to application rate.

Those warnings, from lost breathability to whitening and slip, are set out maker by maker under whether pavers can be resealed too often, and what the build-up looks like on a finished surface is covered at what over-sealing looks like on pavers.

A correct coat count applied badly still shows on the surface. A clogging nozzle, wind and traffic before the sealer has dried are among the application faults ICPI names for the day itself, laid out at the limits of a sealing day, and roller marks are a question of their own, covered at why roller marks show up after sealing.