I've got kind of whispy lashes, not super thick or naturally long, and kind of medium brown in color. I've found that whether or not a mascara clumps very often depends on the application technique used. I always use a very small, skinny spoolie brush or stiff, tiny fan brush for my bottom lashes to prevent clumping or making a mess beneath my eyes, not the applicator that comes with the mascara. I use the same spoolie for my top lashes as well. You can also try a metal-toothed lash comb, which also works really well. Best waterproof mascara I've found is L'Oréal Double Extend. It's a double ended product with lash primer on one side & mascara on the other. The primer has fibers in it, which really helps with lengthening & volumizing, although I don't always use it on my bottom lashes. Generally only when I have a bit more time. It does work well for making my bottom lashes stand out more, however. Try applying some lash primer first on the top & bottom, comb through your lashes to make sure they're well separated, then let dry for 20 seconds or so. Next, apply your mascara, combing through again & allowing to dry between applications. Using the product I mentioned, along with the technique, I can easily layer my mascara 3-4 times & not get any clumping or nasty spider lashes. Lancome & Estee Lauder also make very good lash primers, which also have fibers. I'd avoid Dior's, though. I don't find it does much of anything at all, considering the price it's sold for.
