Wallpaper sizing is a diluted paste solution applied to a wall prior to papering. Sizing improves adhesion but leaves behind a residue when stripping old paper. Removal of this residue is necessary prior to papering or painting the wall surface. The process involved in removing wallpaper sizing will depend on whether any additional steps, such as sealing, took place prior to papering the wall. Sizing and sealing are not the same and steaming an unsealed wall may cause water damage. If you know the wall was not sealed or if you are not sure, manual removal is the best option.
Protect yourself from serious injury by turning off all electricity to the room.
Fill the sprayer with warm water and 2 tbsp. dish soap. Pump the sprayer to pressurize and adjust the nozzle to a fine mist setting. Setting the spray to a fine mist will prevent over-saturation and possible damage to the wall. Fill the bucket with clear, warm water.
Working from the top of the wall to the bottom, spray an area easy enough to work. It will take approximately three to five minutes for the solution to start working so spraying one area ahead will enable you to keep working.
Use the mud or putty knife to scrape the wall section. Clean stubborn spots by gently scraping the wall using the grill cleaner brush. Depending on the amount of sizing on the wall, you may need to repeat the spray/scrape process.
When the area is free of leftover sizing use the sponge and towels to rinse and dry the area. Run your hand over the wall to make sure it feels smooth and clean.