Snail polish

(S)nail polish comes in all sorts of colors from many brands. We use it primarily to mark the shells of snails which we are rereleasing into the field. Therefore, we need snail polish which holds its color for weeks in the sun, and doesn't chip off too easily. At this point there are a few brands which seems to work well, and one that definitely sucks.

The Great: Sinful Colors Professional, Blue
The Good: Almay Hypo-Allergenic Nail Enamel, "Fire"
Wet 'n' Wild Nail Color, Red 406a

The Bad: Revlon Nail Enamel, "Sunsparks" 650

The Sinful Colors blue nail polish is awesome, it stands up well to sun and chipping, and blue is a great color for finding snails in the intertidal.
The Almay and Wet'n'Wild are decent also, they hold up to sun exposure for a few months.
The Revlon, although it probably cost the most out of any of these nail polish brands, is absolute garbage when it comes to sun exposure. After 3 weeks in the sun, the majority of our snails have faded to a light tan color, making them hard to find.

It should be noted that supergluing tags onto nail polish is a risky proposition. We've lost several tags which peeled off of the nail polish underneath, perhaps because it was just too smooth a surface for the superglue to adhere to. I would recommend leaving the portion of the shell which will hold the tag bare, and glue directly to the shell. The usually porous shell material bonds very well to superglue, and we have many tags still surviving after 6 months in the field.

Our snails always get a topcoat of clear topcoat nail protector over the colored snail polish and the glued on tag.

Instead of purchasing tags, I started using homemade tags. The tags are printed in a laser printer on HP LaserJet Tough Paper, which is a plastic-based paper. You can print in black or in full color on this paper, and then cut out your tags. Black ink is the most persistent under UV exposure, so don't rely too heavily on numbers or markings made with colored toner. Use the color to make the tag noticeable in the field.
It should be noted that superglue (cyanoacrylate) will dissolve the laser toner off of this paper, so you need to excercise care and only apply superglue to the underside of tags. Give the dried tag a top coat with clear nail polish.