I don't find it goes hard - except for the open end which simply dries out. The ready sliced bread usually comes pre-packed in a plastic bag which keeps the moisture in, so all you need to do is either keep your uncut bread in a similar plastic bag or keep the first slice back and use that to press any further cut edges against, using the weight of the loaf to hold it down in the breadbin. Another way is to keep your bread in one of those old fashioned bread crocks which are now very popular again, they seem to re-moisturise the bread somehow...