Scotch-Brite Clean and Strip XT Pro Disc - Rust and Paint Stripping Disc - 4.5” diam. x 5/8-11 Quick Change Thread - Extra Coarse Silicon Carbide - Pack of 1

I used this to remove *heavy* mill scale from all the surfaces of a 10” piece of W8x40 I-beam. It took probably 65% of the disc to do it but it did an outstanding job. 3M states it’s only for light mill scale; mill scale doesn’t come much heavier than what I used it on. And no danger of cutting into the good steel or dishing it.

Remove mill scale, got about 10 minutes use. Stay with flapper wheel much faster and a way more cost effective

I bought this disk to remove mill scale and light rust. It does do a good job cleaning both, but it wears out rather quickly. I purposely used light pressure hoping to make it last. I will not buy another one.

Love it. Strips paint quickly without damaging the metal underneath.

It worked great but didnt last as long as I would have thought.

I have pretty much every kind of grinding and finishing tool, and probably 30 electric tools: disc sanders, angle grinders, D/A, orbitals, air grinders, what have you. Metal worker for 40 years. Honestly these discs are pretty amazing. First encountered them on a drum type surface conditioning tool meant for metal brush finishing. Used that machine on some aged wood with old paint - super fast and smooth finish. Went looking for a disc style because its smaller and more versatile. Sandpaper and grinding discs are slow and wear out fast in comparison to these. They dont load up with paint so amazing stripping paint from wood, metal, concrete. I bought these specifically for a basement upgrade project. To clean concrete residue from timber, which is a slow job with a regular sanding disc or D/A. Could use a wire wheel but they are slower and dig out the grain a lot more. And discovered on the same project that these are perfect for stripping old paint off the concrete floor, and for cleaning the concrete walls. Those are all tough jobs with few quick solutions. Awesome. (If rather a dusty job!) I went with 3M because the discs last a long time, and 3M is not generally the cheapest but their sandpaper usually lasts the longest. This will clean rust and paint off concrete and stone like nothing I have seen. Leaves a fairly smooth finish. The grades of these are oddly named. The green one is coarser, more aggressive, but leaves more scratches. The purple one looks almost identical but leaves a finer finish. I would probably go with purple first but if it seems slow switch to the green. Rust is easy with these things but mill scale on steel is about the toughest coating on earth to remove. I would think green better because its more aggressive. Scale will still wear these discs out. A grinding stone disc wears longer but bounces around and leaves a much more scarred up surface. For stripping paint and rust, cleaning stone and concrete, metal finishing, lumber cleaning, bbq grills - this is hands down the one disc I would recommend most people have in their tool shed. The only negative thing I would say is that a mini-grinder tends to spin at over 10,000 rpm which is just too fast. I put these discs on a 5 Makita sander that runs about half that and its much easier to control, but the arbor needs to be adapted which is a longer story. If you can find a mini grinder with adjustable speed that would be ideal but they are not common.

Did not hold up as well as I hoped. Bought to strip mill scale on some plate steel. May work on lighter mill scale, but didn’t hardly touch mill scale on 3/4 plate.

If you work with metal you know how difficult it can be to remove mill scale. This product does an excellent job and does not become ineffective after a few minutes. It also leaves a nice finish on the steel. It is also effective in removing rust. I do wish it would last longer but still worth the reduction in aggravation.

This disc makes mincemeat of mill scale WITHOUT removing base material as is common with flap discs. I was able to remove mill scale from a 7 deep x 7 tall x 6 feet long steel bumper in under an hour, then finished up with sanding in stages to a 180-grit finish for priming and painting. I ended up using one complete disc and just a bit of a second, but still have some remaining use of the first, which Ill use on smaller pieces when needed. I tried other off-brand non-wovens that are silicon carbide based, but they didnt seem to be as effective as the 3M product. Im sold.

Works great and lasts longer