Zipper problem diagnosis

Don’t know for sure. The nylon teeth of other type of zippers seem quite stable with heat, time, use and dirt, it’s generally the slider metal wearing that causes problems. My guess would be heat or time has changed the characteristics of the waterproof material making it stiffer and shrinking it somewhat. Maybe the endocrine disrupting plasticizer has off gassed away.

Dave, thanks. You once advised zipping pyramids shut from inside before putting in the pole, which I sure wish I’d done in this case. The stress on the zip must have been pretty high, for it appears to have deformed the DCF adjacent to the zip. Zipper was strait and taut before, wavy after.

Does the convex appearance of the zipper tell you anything?

You could be right.

The first thing I do is replace the slider rather than the whole zipper. I haven’t done so on that type of zipper, but it looks like Ripstop by the roll carries that type of zipper and would have the sliders. Perhaps order one or two, undo the stitching at the top of the zipper, slide the old one off, put on the new and see how it runs. If better, restitch the top, perhaps with a little patch of fabric to reinforce at that spot. This can be done by hand pretty easily. It’s not a bad idea to keep an extra slider on hand as the metal can wear away over time, which prevents the zipper teeth from being pushed together enough to engage. (You probably already know this, but posting for others as well.)

I’ve had issues in the past with #3’s not holding up on my diy pyramids. I haven’t had this particular issue, but I have had what I call the wave in the zipper. That issue was caused by stress. I over tightened my door tie-downs. I had to replace the zipper and have used a #5 ever since. A bit more robust, not a terrible weight penalty.   I hope the zipper slider idea works. Is this a Locus Gear tent? Reach out to them, maybe they have a solution. Please keep us posted.