W. R. Meadows Deck-O-Seal Pour Grade Two-Part Polysulfide Joint Sealant Kit, White, 24 oz, 4701021

Deck-O-Seal from W. R. Meadows is a two-part, polysulfide-based joint sealant made for the moving joints on swimming pool decks. This is the pour grade, a pourable liquid that levels itself in the joint, in a white 24 oz kit, part number 4701021.

How it performs

After mixing, the sealant cures at ambient temperature into a firm, flexible rubber that resists tearing. Once cured it can stretch or compress by as much as 25 percent as the deck expands and contracts with temperature, which keeps the joint closed and helps stop random cracking across the slab. It holds up to UV, weather, moisture, abrasion and pool chemicals without going brittle, it does not stain, and it meets ASTM C920, Type M, Grade P, Class 25, NT.

Getting the joint right

Joints need to be clean, dry and free of dust, laitance and curing compound, and new concrete should be fully cured, which the industry takes as 28 days. The sealant goes in joints from 1/4 in. to 1 in. wide at a depth between 1/4 in. and 1/2 in., keeping about a 2:1 width to depth ratio, and a backer such as Kool-Rod or Deck-O-Foam sets that depth. It bonds well to bare concrete, and W. R. Meadows recommends Rezi-Weld LV primer for the best adhesion. Masking tape along both edges keeps the deck clean, and it has to come off before the sealant starts to set.

Mixing and cure

The kit is pre-measured and the ratio of setting agent to base must be kept, so mix all of it, and only when you are ready to apply it. Pour the small can of setting agent into the base and mix slowly for at least 10 minutes, scraping the sides and bottom until the color is even. At 77 F you have about an hour to work. The 24 oz kit has no applicator bottle, so use a caulking gun or a similar applicator. The sealant is tack free in about 4 hours and firm within 24 hours, longer when it is cool. Wear safety glasses and chemical resistant gloves, and clean tools with xylene or toluene.

Where not to use it

Deck-O-Seal cannot be used underwater, so choose Deck-O-Seal 125 or Deck-O-Seal Gun Grade for joints below the waterline. It is not compatible with asphalt or asphalt impregnated joint fillers, it should not be painted over, and it is not recommended where there is aquatic life.