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Thanks to this step we can remove a first surface of dirt: your sponge will turn black. Then wash the sponge and pass it on the dirty surfaces to remove any residue. If the situation still does not convince you, it is time to get the foil.

Weave all affected surfaces with the previously created liquid. Then roll out a sheet of foil to cover the whole area. Leave on for at least five minutes.
After the necessary time you can continue: when you remove the card, you will notice that all the dirt has remained attached to you. Thanks to aluminum, the limestone softens and disappears much more easily. Accartoccia the film and use it to scrape any residues. Then wash everything: there will be no trace of incrustations!