OATEY 31321 1.5 in. x 10 yds. 180 Open Mesh Cloth

It is an abrasive cloth for prepping copper pipe and fittings before soldering. The 182 grit cleans, polishes and deburrs the pipe end and the fitting socket so flux and solder wet the metal properly. Use it right before you flux and sweat the joint.

The 31321 mesh cloth is rated for both wet and dry copper piping, so it works on a repair line you have drained but cannot get fully dry. The open mesh also resists corrosion, which is why it holds up on damp work. Note that the water still has to be out of the joint before you can bring it up to soldering temperature.

Open mesh is the one most plumbers reach for on copper. The mesh lets the copper swarf fall through instead of loading up the grit, so the strip keeps cutting and does not glaze over the way a closed-back emery cloth does, and it tolerates wet pipe. Solid-backed emery cloth is better when you want a finer polish on dry stock. For sizing a fitting socket on small-diameter tube, a wire fitting brush is faster than any cloth; the cloth is for the outside of the pipe and for reaching into larger sockets.

The 31321 cloth only does the prep step. You still need soldering flux, lead-free solder, and a torch, plus a tube cutter and a deburring tool or fitting brush if you are cutting new pipe. Clean with the cloth, flux immediately so the bright copper does not re-oxidize, then sweat the joint.

No. At 182 grit the cloth is cutting oxide and burrs, not metal of any depth. A few passes to bring the pipe to bright copper is all a solder joint needs, and that is well short of anything that affects a type M or type L wall. Over-sanding one spot for a long time is the only way to do harm.

Yes. A roll weighs 0.4 lb and takes up 0.02 cubic feet, so an MRO or service stock of several rolls adds almost nothing to the truck. Buyers standardizing a crew on one prep item usually keep one roll per tech bag plus spares on the shelf.

Oatey lists the 31321 mesh cloth for copper piping and copper fittings. It will scuff brass as readily as copper since both are soft, but the product is specified for copper pipe and fitting prep ahead of soldering, not for scale removal on steel or galvanized. For threaded steel, use a wire brush and thread sealant instead.