Ink removal can be a very challenging industrial process. First, this is hard because most inks are formulated to be permanent and very durable. Additionally, inks are formulated from a wide variety of different fluids and chemistries; while many are alcohol-based there are many other carriers that might be used. For example, epoxy inks are virtually indestructible. Finding a solvent that is safe for people and still has the cleaning power to remove these versatile materials without damaging the substrates can be highly problematic.