I used to commission building automation systems, spent a lot of time in the field. Could this be the goo the electricians use to lube the cable when its pulled through pipe.....? Its bright yellow when its in the tube, gets greased on the cable as its pulled.
Nylon 6/10 is classified as a strategic material, you can't legally send it into China. The good news is that the Chinese have made Nylon 1010 locally and its much cheaper. The data sheets for Nylon 6/10 apply. I have been using Nylon 1010 on several projects, recommended.