How can I remove coffee stains from porcelain stoneware?

When a product that causes stains (coffee, olive oil, varnish, etc.) is spilt, this should be cleaned up immediately with a damp cloth. If the product is allowed to dry on the floor, this may cause staining which can only be removed using a product suitable for this purpose.

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(*) The products of the companies mentioned are merely examples. There are many other companies besides these that have quality products.