litchin, its a bum, the only way to get it off patios or driveways, is to use a very powerful pressure washer, mine is 3600psi, and only when i hold the nozzle one inch away it gets it off,
i had it once on a conservatory, i used a yellow microfiber sill cloth on the end of some bamboo, which i found, and it came off, but if its on there your best bet is to get some Powerfull, hard surface cleaner from janitorial supplies, wont shift, it but its softens, so you can get it off with the cloth