While it is important to ensure the design or message of a graphic remains undamaged by cleaning, in most situations, it is the adhesive that is most crucial.
By David Morgan
It is always important to keep signs and graphics clean for esthetics and clarity of message, but COVID-19 (coronavirus) has made hygiene a priority. Hospitals, transport hubs, and contaminated sites are undertaking deep cleaning to prevent the spread of the virus, ensuring everything—handrails, doors, windows, ceilings, floors, furniture—is sterilized. Many of these surfaces may have graphics applied, possibly communicating essential information. Elsewhere, many businesses and organizations are using downtime to clean their premises from top to bottom now, or will need to sanitize before they reopen at a later date. Retailers, shopping malls, restaurants, bars, museums, galleries, offices, and educational facilities—these will all have signage and graphics that will be part of the cleaning process. With communication key and budgets shrunk, it is essential these printed materials can withstand heavy-duty cleaning without having to be replaced.
Wall murals, decals, floor graphics, window displays, and signage may all need cleaning, but how to approach this will depend on the graphics material, especially that of its overlaminate product. An overlaminate is used to enhance graphics, but is also essential to protect an underlying image or surface from damage caused by ultraviolet (UV) exposure, scratches, graffiti and, indeed, cleaning chemicals.
Choosing the right cleaning solutions
This is where selecting the correct cleaning agent for the graphic media is key. Products typically used for disinfecting are in the aliphatic alcohol or two to five per cent bleach category. These are generally fine for polyvinyl chloride (PVC), polypropylene, polyethylene terephthalate (PET) and polychlorotrifluoroethylene (PCTFE) films, used in the majority of graphics overlaminates. Other types of cleaning agents are in the organic solvent family (acetone, [methyl ethyl ketone], and toluene) to which some products such as PET and PCTFE are highly resistant, but will break down the polymer chains and dissolve PVC material. Polypropylene is generally more durable than PVC, with resistance to some organic solvents, but is still susceptible to attack. Ammonia-based cleaners deserve a further word of caution. Ammonia is considered a corrosive, which can not only make the film brittle, but can also attack the graphic’s adhesive. However, cleaning products that contain ammonia have it diluted in the form of ammonium hydroxide, typically in concentrations no more than 10 per cent. PVC has good resistance to this, but PET is only resistant to solutions up to five per cent—although this is all dependent on temperature and exposure length. If the laminate material is unknown, or if there is any uncertainty, it is safe practice to use only alcohol or bleach-based cleaning products, which are proven disinfectants.
