19809 Blue Ghost 4.5 oz

I write secret notes to my kids in their lunchboxes and they light up under the UV flashlight at the dinner table every single night. The ink dries completely invisible, but glows a brilliant blue that’s surprisingly easy to read. This bottle is huge for the price, so we’ll be having fun with this f

The 4.5-ounce bottle feels like it’ll last forever, which is great since I’ve been using it for secret messages and marking documents. I love that it’s bulletproof against water and light once dried, so my notes stay hidden until I shine a UV light on them.

It's genuinely invisible on the page until you hit it with UV, then this wild blue glow appears that's perfect for secret notes and marking documents. The 4.5 oz bottle is a solid amount, so I won't run out anytime soon.