Great for cleaning
I've used all three grades of Sandflex blocks, and I think they're excellent products. The only knock on them, in my book, is that the coarse block can break down pretty quickly if you're using it aggressively - the medium and fine blocks tend to last a lot longer. Basically, they're big rubber erasers loaded with abrasive grit, and just like erasers, they wear down as they're used. This is both good and bad: it means that they can cease to be blocks fairly quickly (again, mostly with the coarse) depending upon the shape of the surface you're cleaning, but it also allows you to shape them if you need a particular profile. When a block I've been using starts to break down, I typically hold onto any smaller pieces and use them for cleaning tight spots. I've even stuck pieces on a Dremel mandrel and used them that way.<br /><br />My primary use for these blocks is tool restoration: they're a great way to remove rust, dust, and "patina" from a plane, chisel, saw blade, or what-have-you that's been languishing in somebody's damp basement or in the back corner of a barn. The coarse quickly breaks down the heavy stuff, and follow-up scrubbing with the medium and fine can take a pretty unsightly tool and make it look respectable. They're not going to work magic - the rust pits and other damage aren't going away - but they can get you back to clean metal. I find that the fine blocks do a good job of bringing shine back to brass, and even used one to remove some scuffs from the plastic bezel of a watch, which came away clear and looking almost new. However, like any abrasive, you have to exercise discretion: if you want to save an etching on a saw blade, for example, work gently with the medium or fine blocks, and keep a close eye on it for evidence of fading. I wiped out the etching on an old Marples gouge once with a couple strokes of the fine block - whoops.<br /><br />Overall, I like these much better than steel wool for cleaning. You can't lap a plane's sole with them - you need a glass or granite plate and sandpaper for that - but they are very effective when used to keep tools free of rust, grime, and general build-up. I use them all the time.
Rating: 4 stars