Wet/dry sandpaper works fine for tumbling polymer clay. One method is cut up the sheets into pieces (chips). One modification to that step is to glue two sheets back to back to double the sanding surface. Another method is to line the tumbling barrel. Many folks combine the chips with the lining.

Sources for wet/dry sandpaper vary. I have not found one place that has all the grit sizes I want (100 - 2500 CAMI), but www.onlineindustrialsupply.com comes close. However, their sandpapers are FEPA, instead of CAMI.

In my neck of the woods, I usually find the coarser CAMI sandpapers in the hardware stores. 3M has a decent online site. Look for 3M Imperial Wetordry Paper Sheets. Note, those papers are also FEPA.

Specialty shops like painting supplies, woodworking or automotive body and paint suppliers, will likely carry the higher grits. But be prepared for some of the staff not knowing there are different sandpaper grades/standards (CAMI vs FEPA). They may even mix CAMI and FEPA grades and not understand the potentially diasterous and counterproductive effects.

For example, one shop I go to has CAMI 600, P800, 1000, 1200, 1500, 2000, 2500. Since the P800 is equivalent to about 450 in ANSI, anyone who thought they were doing well going from 600 to 800 would simply be undoing all the work they put into sanding at 600. What's worse is once one finishes using the 800P, sanding at the higher grits just won't work!

Some of you may have noticed "A" grade wet/dry sandpaper (A = thinner or more flexible paper) tends to curl when it gets wet. This makes it less effective, IMHO, in a wet tumbling environment.

Based on the info at glassattic.com, I glued two sheets, back to back. Note that not everyone takes these extra steps and don't find that a problem.

Of all the glues I tried (water-resistant epoxy, E6000, super glue), I found Devcon's Titanium waterproof 2-part epoxy worked the best. But my, does it stink!

I purchased a paper trimmer to cut the sandpaper into 1/4" narrow strips and then cut the strips into 1/4" square chips.

Note: whatever is used to cut up sandpaper, the blades will be ruined for cutting paper or fabric.

I hand or machine sand (e.g. B&D Mouse) with 320 grit to remove any surface imperfections like bumps and ridges.

I started with my 400 grit chips. I place alternating layers of sand paper chips and beads into the barrel until it's about 3/4s full. The kiddie tumbler should hold about 1/2 cup of beads.

Add water until it barely covers the stuff and add a few drops of gylcerine, seal 'er up and place the barrel into the mechanism and plug it in.

I use glycerine instead of soap, because it helps keeps the sandpaper from clogging with sanding debris without foaming the water too much.

Because the kiddie tumbler has 3 fins along the inside, I don't line the barrel with sandpaper.

Tumbling times per grit (CAMI standard):

When the time is up, I pour the contents into a strainer to rinse the beads and chips.

Note: A batch of sandpaper chips should be effective for about 250-300 hours of tumbling.

Lortone rock tumblers seem to be pretty common, which helps when you're shopping for replacement parts or are looking for technical assistance.

There are many models, so do your homework to decide which model(s) will suit your needs.

I hand or machine sand (e.g. Mouse or Scumbuster) to remove any surface imperfections like bumps and ridges.

When simply adding polymer clay beads, sandpaper and water into my Lortone tumbler barrel, I found the black rubber slightly yellows my beads.

The best thing I can figure is the barrel needs to be lined along the sides, top and bottom with something to protect the polymer clay from constantly rubbing against and getting stained by the black rubber.

If I can locate high end wet/dry sandpaper paper grades "B" or "C" (which are stiffer than "A") and line the barrel with those, I suspect that would work wonderfully. I just haven't searched for those products, yet.

Borrowing from some of the characteristics of my plastic kiddie tumbler barrel, I decided to modify a plastic container and insert that in the Lortone barrel. It protects the beads from discoloration and because I added some "fins" to the container, it promotes tumbling, just like the kiddie tumbler.

Steps I took to modify the 32 oz. polypropylene container are advanced steps.Click here if you're interested.

It takes about 2.5 - 3 back-to-back glued pairs of 9x11 sheets to make enough for tumbling in my 3A Lortone barrel. 1 sheet pair = 1/4 cup chips. I usually add about 1 and 1/2 cup of beads and about 3/4 cup of chips.

I place alternating layers of sand paper chips and beads into the barrel until it's about 3/4s full. Then I add enough water to touch the bottom of the top layer of beads, and a few drops of gylcerine, seal 'er up and place the barrel into the mechanism and plug it in.

Tumbling times per grit (CAMI standard):

I pour the contents into a strainer to rinse the beads and chips.

Note: A batch of sandpaper chips should be effective for about 250-300 hours of tumbling.