I was running out of base coat, and Sephora had been out of stock of the one I had been using (Nails Inc. Kensington Caviar Base Coat), so I ended up picking up Develop 10 Yellow Buster.  The tips of my nails are yellowed so I wanted to see if this “instant nail brightener” actually worked.  I think this is a decent nail brightener, but it’s not a very good basecoat.  When I say it does work as a nail brightener, I mean that it makes your nails look less yellow when you have it on.  I’m not sure if I just had to continue using it, but once my manis came off my nail tips were still yellow.  I still think that growing your nails out is the only way to really get rid of yellowing.  Nail brightening claims aside, I just don’t think this is a good basecoat.  It tends to bubble on the nail, which can make your polish look bubbly in turn.  It’s particularly apparent with creme polishes.  To be fair, I don’t think this is exclusively made to be a basecoat, just that it can be used as one.  I could tell because it doesn’t really do something basecoats are supposed to do, which is hold polish onto the nail!  I tried this basecoat with a couple of glitter-heavy polishes, and by the end of the day, the polish would pop off each of my nails entirely!  (The only good thing about this was that since it came off in whole pieces I could re-stick it to the nail using more base and top coat.)  I know glitter manis are thick and they can be removed by peeling them off your nails, but they’re not supposed to come off when you’re shampooing your hair, or reaching into your bag, or typing on a keyboard!  I figured out Yellow Buster was the culprit after I tried more glitter polishes with a different base coat and my manis stayed put until I removed them.  I definitely wouldn’t recommend this as a basecoat, and because of the bubbling, I don’t think I’d even recommend this as a clear coat, but at least it does provide a temporary fix for yellowing.