Yes, if you use a transparent ridge filler, it can be used under a gel polish. Some ridge fillers also act as a base for gel manicures. If you have trouble painting inside the lines, you have a few options. Some people claim that putting a thin layer of liquid craft glue on the skin surrounding the nails provides a protective barrier, so if nail polish does bleed over it can simply be peeled off. There are also latex peel off skin guards created just for this purpose. Whatever you choose, wait until the skin guard dries completely and then proceed with applying the polish. Get 20% Off on Your Birthday! According to Amazon reviewers and their top-selling statuses, these are the best nail ridge fillers the internet has to offer. CONFIDENCE, COMMUNITY, AND JOY Since it’s filled with natural silk protein fibers, BARIELLE hydrating ridge filler smooths and restores your nails — but it also hydrates and protects. This formula is best used as a base coat prior to nail polish, so in addition to smoothing ridges, it can reduce brittleness. Most importantly, while it’s loaded with nourishment, it skips a lot of the not-so-great stuff like formaldehyde, toulene, camphor, and parabens. It’s even vegan.