We're having a really difficult time, especially over the past week or so, keeping visitors from tracking snow and salt into the museum. Is there a particular type of doormat that might be more effective at this? We had previously been using coir mats, but they wore out, and the replacements (a combination of materials) don't seem to be working as well. Before we go back to coir, and move on to our second replacement set of the season, I wanted to ask if anyone had experience with something that works particularly well.