These are the care instructions I've found on the olfa website:
OLFA ROTARY MAT CARE INSTRUCTIONS
• Use only Rotary Cutters and Blades. Knives with a fixed blade may damage this mat.
• Keep mat flat, never rolled.
• Do not expose to extreme condition. Keep out of direct sunlight. Both cold and heat
could cause the mat to crack or become brittle.
• Do not iron.
• Avoid cutting repeatedly in the same spot to avoid excessive wear. For double-sided
mats, rotate and flip mat periodically.
• To clean, use lukewarm water with a mild detergent. Avoid harsh chemicals.