I had a slate floor installed in my kitchen a few years ago. I vaguely remember that it was sealed initially with linseed oil (can that be right?), and that I was instructed that it needed to be sealed again at some point. Can anyone tell me if it does, in fact, need to be sealed again, and with what? Also, where would I purchase whatever I need to seal it with? And how do you "seal" a floor? And finally, how should it be cleaned? Think my cleaner has just been using soapy water, but am not sure if that is the way to go. Thanks in advance for your help....