Here we will try to help by giving you some tips on cleaning slate, they are as follows;
1 Candle wax, this is not easy to rectify, use quality blotting paper and a hot iron. Place the blotting paper over the wax and then place the iron on top of the paper, keep moving the paper until no more signs of wax appear. The slate is fine under the heat but watch the blotting paper. You are trying to draw the wax out into the blotting paper.
2 Water marks, usually left by vases etc, this is usually just washed off with warm water and a SMALL amount of soap (washing up liquid), wash thoroughly and then repeat with just warm water to clear away any soap.
3 Stubborn marks, if you have tried water and soap and this has failed the you could use a stone acid cleaner, this is quite a drastic measure if all else has failed. Mix the brick/stone acid with water in a 50% ratio to start with then follow the acid manufacturer’s instructions, be very careful of surrounding materials i.e. carpet, soft furnishings etc. Once this is done wash with plenty of clean water.
4 Scratches and surface marks (may include white marks). You can redress the slate with a fine wire wool, you will find that this may dull the area and you will need to feed the slate with slate oil or WD40 to return its shine. You may need to do the complete surface in order to create a matching surface look, again take care with surrounding materials and soft furnishings. You can spray a little WD40 onto the stone and work into the area with the wire wool.
I hope these tips are useful and they manage to remove any marks you have. Slate, as with other stones are porous. If you want to put anything containing liquid onto it always use a mat, any spillages should be mopped up straight away, if left they will soak in and stain the stone.
I wish you luck with the cleaning, please feel free to give us a call if you need any further advice.