Hi, I have a limestone fireplace, cream in colour but I'm not really sure how I should be cleaning it. There are stains on it that seem to be difficult to remove. for example, the kids with butter fingers touching the side of it etc... I usually try to clean it with warm soap and water, It doen't do it any harm but because limestone is so porous, the stains seem to be there to stay. It is a lovely fireplace but it seems to be turning a yellowish colour overtime. I have trawled the internet looking for a specialist cleaning product but no luck. Just wondering if any of you out there know of anything that I could use to clean it. Thanks