Set is not the same as hard

A floor can look finished and still take a print. The hours below are the earliest we will write on the board. They are not a dare.

The board is taped to an upright or to the door. It names the aisle, the system, the pour time, the foot time and the wheel time. If your shift supervisor does not read English, we write the hours in numerals large enough to see from a seat, and we will add a Hebrew line on the card if you ask the night before. The example above is a summer self-level. A January pour of the same system moves the wheel time out, not in.

Summer on the coastal plain

July and August in an uninsulated Holon or Rishon shed often pass 30 degrees by mid-morning. The resin kicks faster. Pot life shrinks. We start at 06:30 and we stop laying when the slab is too hot to keep a wet edge. Foot traffic can be the same evening for a coating or a self-level. We still do not hand the aisle to a forklift that afternoon. A warm film takes a thumbnail and dents under a wheel. The dent is permanent. It is also, on a quote, the client’s traffic, not a material defect — see the cure window.

Humidity is the other summer problem. Some hardeners blush when the air is wet and the film is still open: a greasy haze, not a structural failure, but ugly on a showroom top. We pick the hardener for the month. We do not wash the floor the next morning to “clean the haze.” Water on a young film makes it worse. Wait for the wheel time, then wash.

Winter

December to February, a shed that was 33 degrees in August can sit near 8–12 degrees at dawn. We measure the slab with a thermometer. The forecast is gossip. Below the minimum printed on that resin’s sheet we wait for the sun on the concrete, or we move the day. We do not add a random thinner to make a cold mix pour. Winter hours on the specification are the long ones: self-level feet at 24–36 hours, forklifts at 72. A floor walked at twelve hours in January prints every boot.

Polyurethane cement is less fussy about speed and more fussy about a cold substrate. If the bay is cold we hold feet overnight and wheels for about 48 hours. “It feels solid” is not a measurement.

Friday and Saturday

We will not leave a wet floor running into Saturday. Friday work stops by early afternoon, 12:30 at the plant and earlier on a site if the cure would still be open at dusk. Saturday the yard is closed. We do not pour, we do not grind, and we do not book a visit. If a board says Thursday wheels and someone drives on Wednesday night, call us. We would rather look at a print on Friday morning than hear about it on Sunday, when the print has been polished by a full shift.

What early traffic does

Boots on a soft self-level leave crescents. A pallet jack leaves two polished lines. A forklift on a thin coating cuts through. A hot car tyre in a garage is a small press and will brand a coating that was only walked on. None of these sand out cleanly. The repair is a grind and a new body in that bay, at a new price, because the first cure was not kept.

Washing, covering with cardboard, and dragging racking back “carefully” are all traffic. Cardboard sticks to a young epoxy and comes up with the sheen. Leave the bay alone until the hour on the board.