Tefgel is pretty good stuff. Very sticky but seems to work very well. Buy a bigger tube of it and it works out cheaper.
Lots of info on its website
www.tefgel.com.au/ Seems ok for the environment too, this information is off its website:
Non Toxic Information Other key features that make Tef-Gel? unique are - Non Toxic and Non Harmful to Marine and Land Based ecosystems and us
- Non-reactive and chemically stable
- Has an Indefinite shelf life and working life
- Working temperatures of -60? to 280?C without changing viscosity