MULTI-PURPOSE PUTTY GALLON

Yes. J-B Weld's support team confirms it works for patching cracks and holes in plaster, and the cured patch sands. Clean loose material out of the crack first, press the mixed putty in, and let it cure about 20 minutes before sanding flush. Prime and paint afterward so the patch matches the surrounding wall.

The ratio is 50 parts putty to 1 part cream hardener by weight: lay a bead of hardener across the diameter of each scoop you take out. It sets in 3 to 4 minutes and cures in about 20 minutes. With a gallon, scoop and catalyze small batches as you go rather than trying to mix a large amount at once.

J-B Weld does not publish a square foot coverage figure, because how far a gallon goes depends entirely on how deep the voids you are filling are. The gallon is sized for large or repeated jobs, such as a long run of deck boards, siding or trim. If you only have a few small repairs, the quart is the better size.

No. It is a cosmetic filler, not a structural repair, so do not rely on it to carry load. Stabilize rotted wood with Wood Restore Liquid Hardener first, then fill. It is not UV resistant on its own, so any exterior patch needs to be primed and painted once cured, or sunlight will break down the surface.

Wood, metal, concrete and drywall. Clean with a degreaser, sand the area with 80 grit or coarser down to a sound surface, and wipe with acetone before filling. Painted surfaces need sanding first. It will not stick to low surface energy plastics such as polyethylene and polypropylene, so test an unknown plastic on a scrap before committing.

Keep it indoors between 50 and 80F and seal the lid firmly after every use. A gallon gets opened many times, and air exposure and temperature swings are what shorten its life. Do not return mixed, catalyzed putty to the can, because it will cure the rest of the contents. Use a clean tool for each scoop.