- clay or earth based (Fullers Earth - see history of cat litter)
- wood based
Earth based litter clumps, yes, so it is easier to remove from the litter tray but the absorption is less good and the clump is wet as is the surrounding area sometimes. This translates into a more difficult cleaning up job as the litter tray itself becomes stained. With wood based litter the tray does not become stained and there is therefore much less ongoing maintenance of the tray itself. This offsets the slightly greater amount of work needed to separate out the used and unused wood based litter after use.
The main point is that the extra absorption qualities means it is a better Odor Control Cat Litter. One other thing. I use a covered litter tray to stop the wood litter being pushed out onto the floor and I put the litter tray and cover in another low level tray that is considerably larger to collect any litter that is walked out by my cat. The cover also helps to keep any residual odor in and they are not that expensive to be honest.
No.2s will smell in any cat litter unless it is covered by the cat. Sometimes mine doesn't cover it so I do it for her until the litter is removed, which should be at least once a day. Some people recommend more often but daily seems about right to me.
Odor Control Cat Litter to Home page
Photo: Clay based cat litter - clumping cat litter but not as good as an Odor Control Cat Litter - wood based. Photo by BrittneyBush under a creative commons license Attribution-NonCommercial-NoDerivs License