What shouldn't it be used on?
Be aware however, that with this bar being a mechanical cleaner, it can be mildly aggressive to some surfaces. Always test a small area first!
Do not use the bar on anything that is easily scratched like clear plastic, polycarbonate or plexiglass. Anything that is shiny or polishable, painted or varnished (like carbon fibre, or wood etc) as it can micro blemish these surfaces, requiring a professional polishing to bring back their shine.
Be extra careful on soft materials like vinyl and especially leather, which is a soft polyurethane coated material. Just remember it should be used as the very last alternative to our liquid cleansers Vinyl Care, Fabra Cadabra and Leather Love for removing any marks, and you need to use it gently on both these surfaces, as you can slowly wear through if you are too aggressive.
Also, the bars surface will slowly wear out and lose its effectiveness over time. So unless it's a large area you need to clean, we suggest cutting the bar into smaller portions with scissors, and use all 4 sides, rather than wear out the entire bar on one job.
The two bars we have in our kit are more than enough to clean even the biggest interior jobs we've tackled.