Ultimax Cork Lubricant is the perfect cork grease. Ultimax lubricants are safe and inert, meaning they will not break down adhesives like those that hold cork to the instrument. Ultimax Cork Lubricant is also safe for use on hard rubber and wood, it will not damage wooden clarinet bodies or hard rubber mouthpieces. More than just being safe, Ultimax Cork Lubricant holds moisture in the cork keeping the cork soft and pliable. This allows cork to last longer and retain its shape, enabling it to function more effectively.