The tape test for adhesion determines if the leather or vinyl is, after cleaning, able to receive a new finish. See it demonstrated here at minute 2:28:
If painter’s or masking tape strongly adheres to the surface, such that you have to pry it off with a fingernail, you’re ready to proceed with restoration.
If the tape does not stick well or curls up at the corners, this indicates residue from silicone, wax or oil-based conditioning products, other cleaners, or body oil. This residue must be removed in order to get a durable finish. Clean the surface with denatured or rubbing alcohol and re-test until good adhesion is achieved. Lacquer thinner can be used without damaging the material. Acetone can also be used as a last resort with caution.
Tape does not adhere all that well to bonded or faux leather, and we do not recommend restoring these materials.
I purchased some used sofas . They are seriously worn but they were exactly the shape and color I wanted, as I began trying to restore them with just a good cleaning and conditioning I realize I really don’t know what type of leather I’m working with, the brand is rappalo from Mexico and it says top grain leather but some not worn areas have a pretty thick coating and when using 91% rubbing alcohol the high shine kinda dulls and a very little bit of color come off but overall the color doesn’t really change. Also at the edge of the leather it looks almost like veneer. Some of the worn places look very much like genuine leather. I just don’t know what I’m working with and I’m worried my plan of deglazing, filling some spots and then doing a recoloring balm may not be the right approach and I don’t want to completely ruin the sofas before I can replace (not in the near future). Please help I’ve studied and studied but just can’t find anything I feel confident moving forward with.
We’d need you to submit the evaluation with photos for our professional assessment and a tailored solution. Balms only work on absorbent leathers. This pair sounds like they may be non-absorbent.