Ship Modeling FAQ, Question SandPaper --- Revised: August 27, 2003

I found no reference to Sandpaper in your terrific FAQ. I am curious as to what grades of paper I will need. Regular or wet/dry sandpaper? I purchased a set of the fine files, but no sandpaper yet. Thank you!
{Jeff in San Diego}

Sandpaper (equivalent to the British "glasspaper") consists of an abrasive (in a specified grit size) bonded to a flat backing (it also comes in belts, bands, drums, and disks for power tools). There are a large number of backings, bonding agents (the glue), abrasives, and coatings.

What you will need depends on what you are trying to do. 12000 grit is great for polishing paint, but not much use for hogging material off a bread-and-butter hull.

Backing

Backing materials may be a variety of paper, cloth, plastic film, and mesh; paper is the most common, but shreds easily. Cloth is tougher, but can tear. Mesh provides a cushion, and allows the dust to escape.

Bonding Agent

"Wet-and-dry" is waterproof; most others aren't. The only reason you're likely to want to wet it is to polish a finish, or for sharpening tools.

Abrasives

Sand (no, not the stuff off the beach – that has been ground smooth, and you want sharp edges!): the oldest abrasive (and probably least useful any more). Actually consists of ground-up quartz rock.
Garnet: Although inferior to modern day abrasives, has a soft cut and leaves the smoothest finish of all abrasives; therefore well-suited for final sanding of wood surfaces.
Aluminum Oxide: the work-horse of sanding; long-lasting and often called "production paper". Real "emery" is a variety of Aluminum Oxide.
Silicon Carbide: Very hard black material; usually the abrasive on "Emery paper"; commonly found as "wet/dry" sandpaper.

Coatings

Some sandpaper may be coated with zinc stearate; this is a waxy material which helps keep the sanding residue from clogging the paper; useful for sanding paint and plastics.

Grit

The size of the grit is measured by the size of a screen that the grit will pass through. 100 grit is (roughly) equivalent to 1/100th of and inch. Not all abrasives have all grits available.

Common Size	(Grit) Sizes
course	less than 60 grit.
medium	60, 80, 100
fine	150, 180, 220
extra fine	240, 280, 320, 400, 600
super fine	800, 1000, 1200
polish	1500, 1800, 2400, 3200, 3600, 4000, 6000, 8000, 12000

Sanding

There are a number of common rules for sanding:

Back up the sandpaper with something hard – just holding it in your hand will likely generate humps and hollows.
Sandpaper scratches the surface, and stays sharp by shedding abrasive. So, clean the surface thoroughly when changing to a finer grit – otherwise a courser grit may turn up later and make big scratches; then you'll have to go back to that size grit paper and start over.
NEVER sand until all cutting is completed – those same grids that have been shed can quickly dull your cutting edges!
Changing from one grit to another within a common size doesn't buy you much; going from one common size to another does.

{John O. Kopf}

I use emeryboards for a lot of coarse sanding. They are cheap, can be cut to any shape of tip you want, or to expose fresh sanding surface, and you just throw them away when used up. I also use a thin springy piece of wood, about a half inch wide and 9 or 10 inches long with # 220 wet/dry paper glued to it. When fresh it's 220, when used a while it becomes about 400. It is quite durable, you see. I also have a selection of round sticks, paint brush handles, that sort of thing, in different sizes, which get wrapped with the wet/dry for doing inside curves. I have foam back sanding blocks which are sort of OK, but they blend too much and are too large for many places. They work best, used lightly, for the outside of the hull. For a thickness sander I lay a stick with paper over two blocks the right thickness and pull the work piece under it. You don't need high-tech.
{J B Sanborn}

I usw sandpaper I buy from an automotive store(probably used for body work). It comes in rolls about 6" in diameter, yellow in color with adhesive on the back. It does not load, lasts a long time (a roll should last for years). I have it in 80, 100, and 220 grit. Cost is around $30-$40 a roll. I stick it to shaped blocks, aluminum t-bars, popsicle sticks and even wire and dowels. For finer sanding I use wet dry in the finer grits.
{Kirk Gullach}

Try "Klingspor Gold" non-loading sanding sheets. They are cloth backed sheets and rolls that really do not load up unless you're sanding a finish that has not quite dried. The sand "paper" is available in grits from 80 to 400 and are relatively pricey but definitely worth it. I've been using the material on ship models and wood carvings and am very satisfied with the performance. They have a website. I've no connection with Klingspor except as a satisfied user.
{Roy Ozaki}

Jeff, I think it depends on the finish you want and what you are using for a finish. There is a place for 400, 600, and fine steel wool but they don't do much for shaping and sanding planks into a level surface (on this scale, sanding replaces planing pretty much). On my ship's deck I tried to acheive that bowling-lane sheen with 600 and 800, etc. but the grain is just too big and the wood too soft to polish the wood that way. But after about 12 coats of urethane and buffing with some really fine stuff (don't remember what I wound up using, sorry) it came out really nice. But a lot of people don't want the polished furniture look. I do. You have a lot of choices. I keep a box full of a big variety. I chose not to use the automotive stuff -- it is wonderful but the expense was too great an investment for me. I use wet/dry, some garnet, I'm not too picky about type.
{Gary(osmbird)}

Wet or dry sandpaper, used wet, is wonderful for sanding material which would otherwise load up the paper after a very few strokes. As you say, it is best for cutting the "finish;" e.g., paint and varnish, but also for epoxy and plastic ... anything that will melt from the heat generated by friction.

From a post the other day which suggested that used 320 grit was equivalent to 400 or something like that, No, what used 320 is is a very ineffective tool. New, sharp, unloaded paper cuts quickly and has no large particles to leave gouges. Old used paper is loaded with junk that keeps it from cutting and just has fewer of the boulders that hog out material.

Now if I could just find a source for wet-or-dry, self-adhesive, 6" disks for my pneumatic random orbital sander ... but that's not for models.
{Roger Derby}

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