A kit comprising a tissue dressing material for being applied in contact with the tissue of a patient and a detachment solvent for removing the tissue dressing material from the tissue. A method of treating a tissue of a patient, the method comprising the steps of: applying a water-soluble tissue dressing material in contact with the patient's tissue; and applying an acidic detachment solvent to the tissue dressing material for removing the tissue dressing material from the tissue. A method of treating a tissue of a patient, the method comprising the steps of: applying a liquid tissue dressing material in contact with the patient's tissue; and applying a detachment solvent to the tissue dressing material for removing the tissue dressing material from the tissue. A method of treating a tissue of a patient, the method comprising the steps of: applying a water-soluble tissue dressing material in contact with the patient's tissue; and allowing the water-soluble tissue dressing material to convert into a form in which it is insoluble in water at neutral pH. And a solid material comprising a polymer salt and glycerol, the glycerol content being at least 10% of the polymer salt content by weight, for use in a method of treating a human or animal tissue.