• Place grated Fels-Naptha, boiling water, and borax in a saucepan or bowl.
• Stir it until the soap melts and becomes smooth.
• Allow to cool on the counter (not in the fridge) until it begins to gel. 
• Using a whisk or electric mixer, beat until it foams.

To Use:

• Grab some foam with a clean wet white (so as to not transfer any color to the upholstery to be cleaned) rough cloth or brush, scrub the upholstery, making sure not to soak the fabric. Re-whisk the soap as necessary to get more homemade scrubbing bubbles. As you work, use a clean, damp microfiber cloth to wipe away the soiled suds.
• Rinse with a clean wet white cloth, blotting until all cleaner is removed.