When people walk into our living room, they exclaim: "ooh ! -
paving slabs". After a while, they say "Oh, its only concrete, but
hasn't it been laid well". I think the latter is true. House is one
of five in a terrace, converted from a mill in 1902. All living room
floors are identical, so pretty sure floor is about 100 years old.

Sometimes, small areas of the floor, particularly around the fireplace,
change colour, becoming darker than usual. My wife reckons this happens
when it rains. I'm not so su I think it might coincide with heavy
occupation (many people breathing, cooking etc).

My wife says "Oh no, we've got damp coming up through the floor.
We'll never be able to sell the house !". She wants to rip up the
floor and replace it. I think that's nuts. Apart from colour change,
floor doesn't feel damp, no salt deposits - I even tried laying
cling-film on floor to see if "damp" would accumulate - but floor
is so dry that cling film won't stick and eventually blows away. So I
don't think we have a damp problem at all. This is causing much
domestic tension.

Also, over the years people have dripped paint on the floor, mixed
render on the floor, and generally disrespected it. I wonder if what is
changing colour is layers of soot ?, varnish ? grease ? or who knows
what has ended up on the floor over the years. I'm inclined to take a
serious power cleaner to the floor, e.g. the STR701 Multi Preparation
System
( see http://www.nfpc-hire.co.uk/str701.htm )
to get rid of paint, drips of render, and anything else that's
lurking there - and then seal the floor with that transparent
concrete sealant stuff.

Wife says: "Why waste £200 pounds on machine hire and consumables
when you'll only have to rip up the floor anyway ?".

Is anybody out there brave enough to step into this argument. Anyone
had similar floor, or experience with the STR701. We would both value
your opinions !!