Apply Shellac-Based Primer to Subfloor

What happens here

The presenter demonstrates the application of the Zinsser B-I-N Shellac-Base Primer directly onto the pet urine-stained subfloor. Primer is poured into the paint tray, and the roller is loaded with the product. Using the roller on an extension pole, the primer is spread evenly over all contaminated sections, effectively covering the dark stains and creating a white, sealed surface. The speaker mentions that while a sprayer could be used, rolling is also an effective application method. It's also noted that denatured alcohol is required for cleaning tools due to the shellac base.