Yes, you can clean and reuse both lighting gels and diffusion material, though their lifespan and reusability depend on several factors.
Cleaning: Gently wipe with a soft, lint-free cloth to remove dust or fingerprints. For more stubborn marks, a small amount of mild soap (like dish soap) diluted with water can be used. Always avoid abrasive cleaners or harsh chemicals, as these can damage the material and affect its optical properties.
Ensure gels and filters are completely dry before storing or reusing. Proper storage in a clean, dry, and cool environment, ideally flat or rolled neatly, will significantly extend their lifespan.
Reuse: While some wear and tear are inevitable, taking good care of your gels and diffusion materials will allow for many reuses. The reusability largely depends on how they are used and stored:
Heat Exposure: Whilst gels are heat resistant, they can degrade if not given proper ventilation. It's best to replace filters with heat damage.
Physical Damage: Creases, tears, or scratches will affect the quality of light passing through the material, so damaged pieces should be replaced.