Neatsfoot oil won't rot stitching because it's natural and not a petroleum-based product. Neatsfoot oil is known for using lanolin to polish leather, but that doesn't mean it'll do the same to your stitching. Neatsfoot doesn't have any strong chemicals in its chemical makeup to rot cotton or hemp fibers which are the most common ingredients in thread. That means neatsfoot oil should be good at moisturizing and conditioning old items without compromising structural integrity of stitching!