Cleaning Different Sign Types
Different sign materials require different cleaning approaches. Using the wrong cleaner on the wrong material is the most common cause of DIY sign damage.
Channel Letters & Dimensional Signs
Mild soap and water with a soft cloth or sponge applied to the letter face and returns. Avoid pressure washing directly into letter housings — water forced into the letter cavity can damage LED modules, power supplies, and electrical connections. Never use abrasive cleaners or scrubbing pads on acrylic faces — they scratch permanently. For bird droppings or heavy soiling, soak the area with soapy water for a few minutes before wiping. For the metal returns and trim cap, a general purpose non-abrasive cleaner on a soft cloth is appropriate.
Vinyl Graphics & Window Graphics
Isopropyl alcohol (70%) on a soft cloth removes most contaminants from vinyl graphics — grease, adhesive residue, marker, and general grime. Mild dish soap and water works for general surface cleaning. Avoid petroleum-based solvents (WD-40, mineral spirits, paint thinner) — they degrade vinyl adhesive and can cause edge lifting. For window graphics, clean from the graphic outward to avoid lifting edges. Do not use abrasive cloths or sponges on printed vinyl — fine scratches damage the laminate and dull the graphic.
Painted Aluminum Signs
Mild soap and water is the correct cleaning method for painted aluminum cabinet signs and panel signs. Avoid solvent-based cleaners on painted surfaces — they strip paint and cause fading. A light rinse with a garden hose is acceptable for exterior painted aluminum signs; pressure washing at close range is not recommended. Applying a thin coat of automotive paste wax once or twice per year extends paint life significantly on exterior painted aluminum signs in Ottawa's climate — the wax creates a barrier against UV exposure, salt spray, and freeze-thaw cycling.
Acrylic Cabinet Faces
Clean acrylic sign faces with clean water and a soft microfiber cloth — not paper towel, which scratches acrylic on contact. For stubborn smudges, a plastic-specific cleaner such as Plexus or Novus Plastic Polish cleans without scratching and can buff out light surface scratches. Never use glass cleaners containing ammonia on acrylic — ammonia causes micro-cracking (crazing) in acrylic over time. For heavily soiled acrylic faces, soak with mild soapy water before wiping — do not scrub dry acrylic.
Signs Your Sign Needs Professional Service
Some issues are not cleaning problems — they require repair or replacement. If any of the following apply, cleaning will not resolve the issue:
- —LED modules that have gone dark inside a channel letter or cabinet — not a cleaning issue. Module replacement by a sign technician is required.
- —Cracked or fogged acrylic faces — cleaning will not restore clarity to crazed or cracked acrylic. Face replacement is the correct repair.
- —Faded or peeling vinyl graphics — UV-degraded or adhesive-failed vinyl cannot be restored by cleaning. Vinyl removal and replacement is required.
- —Bent or damaged letter structures — physical damage to the letter casing, trim cap, or mounting hardware requires repair or replacement, not cleaning.
- —Water visible inside an illuminated sign cabinet — condensation or water ingress inside an illuminated cabinet risks electrical damage. The sign should be assessed by a technician before continued operation.