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As part of my parent's business, we own a self catering unit in a popular tourist city. We've had it for five years and just before opening to the market, we had it renovated and placed tiles with a low-grit sandpaper-like consistency (don't know why).

Problem now is in the kitchen, five years worth of grime has accumulated on the floor and we've tried a lot to get it out. My brother and I have suggested a power washer, but idk if its safe to use indoors and with aging wooden cabinets.

Is there a way to get rid of that ingrained dirt?

I understand this subreddit is meant for posting tutorials, but I'd love some help please.

Edit: grammar