Durasole is a sole dressing that strengthens and thickens the cell membranes of the. This product doesn’t affect the proximal sensitive sole or frog. This is not a topical treatment. Durasole swells and thickens the cell membranes. This product is considered safe for long term use. The moisture balance won’t be compromised when used as directed. Durasol is free of copper napthenate and essential oils.