I need to clean and restore a cast iron fire surround, in situ. Is there a proprietary cleaner or is it best done with wirewool. Can anyone help with advice. Thanks.
You need to use wire wool or a softish wire brush to get the rust off, then polish with a "black lead" grate polish. The one everyone used to know was called Zebo, but that seems to be impossible to find these days. However, I think Liberon and Stovax both make a similar product. It looks like black toothpaste - you apply it with a cloth or soft brush (brush is better if you have mouldings to get into) then buff it with a soft cloth. It gives the iron a wonderful "gunmetal" kind of sheen.
By the way, it isn't really lead - I think it's a wax compound. You should be able to find one of the brands in a fireplace shop.
I think probably either - not sure there is much to choose between them. If you prefer a more grey finish Hotspot (which also does a black grate polish) has a grey finish.
The metallic sheen is because 'black lead' is actually graphite, which is what pencil 'lead' is made from of course.
For a first coat, I find as David says a brush (shoe polish type) best, and it may take a second coat too. A toothbrush is useful for fine casting. Then a great deal of elbow grease with another clean brush followed by a cloth. It will look wonderful.
If it seems a little thick from the tube you can mix with white spirit and put a first coat on with a paint brush.
Take care though as it can be messy - put paper down, take care around edges where it meets wall if painted or papered, and don the Marigolds!