Thread: Sandpaper on the bay

Sandpaper has, in essence, three main points for quality. (I'm the son of a professional woodworker, so I have an unholy and unhealthy knowledge and passion for things like sandpaper and precatalysed lacquers.)

1.) The paper: Ideally a sandpaper has a backing that is both highly durable and flexible. Not floppy, mind you, but that can be bent without breaking or forming creases. A good sheet of sandpaper should be stiff enough to hold a shape, but flexible enough to be rolled into a fairly tight tube without forming any angles. (Test this against a known quality sandpaper, like 3M or Mirka). The paper should also be tougher than the grit or the product being sanded- if this isn't the case, you'll find the paper sands through or turns into shreds very quickly.

2.) The adhesive: Good sandpaper will be made with a strong adhesive that matches the flexibility of the paper. A weak adhesive will shed grit all over the place, and ultimately cause uneven scratching. A strong adhesive keeps an even plane, and allows fractile grit to work its magic. Depending on what the paper is made for, this should also be insoluble in most solvents, and stay firm under high temperatures.

3.) The grit: Grit is easy to find, time consuming to grade. A good company will sieve these meticulously, using screens or centrifuges to separate them by fractions of a micron. A company looking to save time and money will be much less careful. One big lump on a piece of sandpaper will make inconsistent scratches- a bunch of them will create a second plane above the surface of the desired grit, keeping you from ever sanding the way you'd like to. This can be evaluated by using hand feel, a dissection microscope, and the way a block of wood/ceramic/glass etc feels being pulled by its own weight across the grit in comparison with a good paper. Every grit will have its own feel- learn roughly what these should be and you'll easily recognize the gliding-rasping feel of a block sliding over too few too large particles of grit. (Think serrated razor- where it catches, it really grabs, but it doesn't catch enough)



Well....that ends my little eulogy. Hope it helps.