Removing wallpaper paste can be a tedious job, but you don't have to buy expensive, harsh chemicals to get the job done. You can easily make your own wallpaper paste remover with some warm water and products you already have at home. With a spray bottle or garden sprayer attachment, or even just a sponge or rag, you can achieve similar results as more corrosive chemical solvents with your homemade solution, minus the fume-induced headaches.
Evaluate how much and what kind of wallpaper paste you have to remove. For lighter jobs, a solution of vinegar and water may be enough to get the job done. For thicker, clay-based adhesives, a solution of dish washing soap and fabric softener might do a better job.
Mix equal parts vinegar and water to make a non-irritating, acidic solvent. Another option is to add 1 or 2 tablespoons of dish washing soap to a sprayer of warm water. You can also combine a half-cup of dish washing soap with a half-cup of fabric softener in a 5-gallon bucket of warm water to create a paste-dissolving solution.
Apply the solution to the wallpaper paste. Whether you spray the solution or apply it with a rag or sponge, make sure to saturate the adhesive thoroughly and allow plenty of time for it to soak in. However, don't get the walls so wet that solution runs down the wall and onto the floor; you want it to hang on long enough to saturate the paste.
Reapply the solution as needed to soften the wallpaper paste enough so you can remove it. Your homemade solvent may take a little longer than its commercial counterparts, but you'll find it more cost effective and environmentally safe.