You can buy a tube of some thick black gooey adhesive for repairing the 'wear down place' on boot heels. It's good but once the tube is opened it can't wait to start 'drying-up' back down the tube. What might be a way to try and stop this process... wrapping the whole tube in aluminium foil? Or sealing the open end with some not to strong glue (like hot glue). Any suggestions ? Thanks.