If you’re installing new wallpaper and have leftover glue, you can remove unused wallpaper paste from the bucket or pan it’s in by letting it dry. If it’s an oil-based paste, seal it in a plastic bag and throw it in the garbage. Otherwise, toss the leftover wallpaper paste in the trash. Although it’s water-soluble, don’t rinse unused wallpaper paste down the sink because it could dry in the pipes and cause a blockage.

As long as the surface you’re putting the tile on is properly prepped, peel-and-stick backsplashes should stay on and last anywhere from 3 to 5 years. The best way to ensure the tile stays on is to sand down and clean the wall before applying your design.

One of the biggest downsides to peel-and-stick wallpaper is that it doesn't last as long as traditional wallpaper. Its lifespan depends on several factors, including the quality of the paper, proper wall preparation and application, and the room's conditions. As a general rule, peel-and-stick wallpaper can last for at least five years, but this can vary significantly. Budget products may only last about 3 years, while higher-quality products can stay up for 7 years or more in ideal conditions. Factors that can shorten its lifespan include high humidity (such as in a bathroom), dirty walls, and low-quality paper. If used on flooring, expect it to last only 1 to 3 years unless sealed. However, the shorter lifespan can be seen as a positive, making it a great choice for people who enjoy switching up their interiors more frequently.

If you can already see the texture of the existing wallpaper through the layer of paint, then the texture could also come through the new layer of wallpaper. If that’s the aesthetic you want, then proceed. But if you want a smoother surface, you should either strip off the existing paint and wallpaper or hang a layer of liner paper before proceeding.