Board bag sticky zip

Last time I used my board, the zip on the bag was clogged up with white cack, which I assumed was crystalised salt. After a LOT of tugging, I eventually got it open, but it destroyed one of the zip sliders. When I got home, I cleaned the zip and got rid of as much cack as possible.
I checked today and the zip is stuck solid again. I store my board in the bag, in my garage.
Anyone else had this and know of a solution as I reckon the only way of getting my board out now is with a Stanley Knife.
I checked today and the zip is stuck solid again. I store my board in the bag, in my garage.
Anyone else had this and know of a solution as I reckon the only way of getting my board out now is with a Stanley Knife.
