Buy a bottle of white spirit..... Use an old baking tray or some kind of metal container. Pour the white spirit into the tray/container. drop your chain into the tray making sure it is all immersed in the white spirit. Leave it for 24 hours.
Take an old toothbrush and brush the chain to remove the stubborn bits. Check for wear and stretching(replace if necessary). When you are finished brushing...hang the chain up to dry(doesnt take long). Lightly lube and fit the chain

If the chain feels gritty before oiling then rinse with clean white spirit until its free from grit.
Hope this helps
