Originally Posted by stevehaun
No need to solder the ends together. Just twist them.
I agree but soldering will make sure they don't loosen up.
The lab I worked at when I was in school used to make their own thermocouples all the time. The tech who worked in the lab would pull some thermocouple wire off a spool then he would twist the ends together and dip the end into a solder pot. Most of the thermocouples were only a few feet long but he made some over 20 feet and they measured fine.
He said back then that the only thing you can't do is splice the wire in the middle. If you needed a longer one you had to start over.