Assembly time is about 15 minutes to 30 minutes compared with just five minutes for yellow glue. Clamping time one hour to five hours compares with about 30 minutes for yellow glue. Polyure-thane lacks the early high tack of yellow glue, which keeps mating surfaces from sliding around, but the slipperiness can allow joints to be unclamped and repositioned for up to 30 minutes after initial clamping. These qualities make polyurethane good when you're gluing complex millwork but can be bad for production work. Lightweight objects can be clamped with rubber bands, string or weights.
Polyurethane glue can be as messy as epoxy.
Uncured glue must be removed with a dry cloth or an approved solvent. Polyure-thane glue also stains skin and, once cured, stays put until it wears off. Disposable gloves, old clothes and safety glasses are mandatory. It's a good idea to squeeze as much air as possible out of opened bottles before capping and to store them upside down so that cured polyurethane will collect at the bottom instead of the top of the bottle. Better yet, don't buy more polyurethane than you'll use in a few months.