I just started using Colgate Simply White, 2 nights ago.
It does come in a bottle that reminds me of white-out, lol.
But, it is a clear whitening gel. The instructions say to apply before bed. You brush your teeth, wipe your teeth dry with a tissue, and then brush a thin layer of the gel onto your teeth.
Do not drink anything or wet your teeth, other than having to close your mouth, lol.
I have been applying it and then waiting a few seconds for it to get tacky, so I can close my mouth. Last night I stood in front of a fan to dry it a bit, lol. In less than a minute, it gets tacky and seems to stay put.
The instructions say it will take about 2 weeks.
I bought it on sale and decided to test it out. I like that I can brush it onto individual teeth, because my 2 front teeth are capped and I'm not sure how a bleach will effect them. With the brush on, I can avoid those teeth.
So anyway...I'll let you know if I see a difference in 2 weeks!