It depends on your surface and the gap you’re covering. Common options include:

• Flexible quarter round molding: A bendable PVC or rubber edge trim that helps bridge wall/tub seams and corners. It’s useful on tile, acrylic, and fiberglass where you want a clean transition.
• Peel-and-stick caulk tape/strips: A self-adhesive waterproof seal that’s quick to apply along shower bases, walls, and countertops. It’s handy for straight runs and light curves.
• Solid-surface molding kits: Trim pieces designed to match solid-surface shower walls for a seamless look.

Consider water exposure, flexibility for corners, and color match. Checking the product’s compatibility with your wall/tub material and measuring the run length can help you choose confidently.

1. Soften and remove: Warm the old trim with a hair dryer and gently lift with a plastic scraper to reduce wall/tub damage.
2. Clean the surface: Remove residue with a mild adhesive remover or rubbing alcohol. Rinse and let it dry fully.
3. Measure and cut: Measure runs and corners, then dry-fit the new molding or caulk tape before sticking.
4. Apply: Peel backing and press firmly from one end to the other. For tight corners, use a flexible trim and work slowly.
5. Seal and cure: If needed, add a thin bead of silicone at ends. Allow recommended cure time before heavy water exposure.

Ventilate the area and follow the product’s instructions; results can vary by surface and humidity.

You’ve got a few workable approaches, and the best choice can vary by gap size and surface:

• Silicone caulk: Good for small-to-moderate gaps along tub-to-wall seams. Clean, dry, tape the edges, run a bead, and smooth it.
• Self-adhesive caulk tape: Helpful for straight lines and corners. Clean thoroughly, peel, stick, and press firmly.
• Flexible molding trim: Adds coverage and a finished look on edges and curved corners.

Prep matters: remove soap scum, let surfaces dry, and avoid splashing until the product cures. For larger voids, a backer rod under caulk may help. Always check the instructions for surface compatibility and curing time.

Start with the gap you’re covering and your surface type.

• Measure gap width and length: Many peel-and-stick trims range from about 0.3" to 2" wide; choose a size that overlaps both sides of the seam.
• Profile and flexibility: Quarter round profiles suit corners and transitions. Flexible PVC or rubber handles curves better.
• Thickness: Thinner tape works for tight, flat seams; thicker molding can hide uneven edges.
• Finish and color: Match tile, acrylic, or solid-surface walls for a cohesive look.

When in doubt, dry-fit a small section first. Product pages typically list dimensions and recommended surfaces, which can help you select confidently.

Adhesion usually comes down to prep, pressure, and conditions.

• Surface prep: Remove soap scum and residue with a degreaser or rubbing alcohol, then let it fully dry.
• Temperature and humidity: Cold or humid bathrooms can hinder sticking. Applying at room temperature and avoiding steam during initial cure can help.
• Firm pressure: Press along the entire run to activate the adhesive, especially at corners.
• Surface texture: Very rough or highly textured walls may need a different trim or supplemental caulk.
• Cure time: Follow the product’s recommended set time before heavy water exposure.

If issues persist, check the instructions for surface compatibility and consider a more flexible molding for tight curves.