Devcon 2-ton (30 min epoxy). The longer it takes to cure, the longer it takes to yellow. Also, if you keep the flies out of direct sunlight during storage the epoxy will stay clear longer. As far as the double syringes go, separate them with a pair of heavy duty scissors. With two separate syringes it is quite easy to get equal amounts of epoxy and accelerator.

Sally Hansons is a great head cement but does not replace epoxy for some patterns such as surf candies, etc. I have no experience with the UV knot sense however the epoxy is very inexpensive.

Regards,
Keith