Final varnish. Superfine Permanent Varnish. Protect your gouache and watercolour paintings with Superfine Permanent Varnish. This extra-fine quality varnish has a slightly satin uniform finish, enhancing the brilliance of your colours, while reducing gouache’s natural matt. Easy to apply with a brush, this is a final varnish that cannot be removed. Apply several layers to achieve a brilliant glossy finish.