Hi... you can easily burn the coating of if you use a lighter.... just put the lighter /flame for a short time on the cable... it starts to burn ... but do not get afraid.. only the sealing is burning... no problem..
after it burned for just a second you can blow it out.. and tin it with your soldering iron!...
i always do this like that... and it is no problem at all...
Good luck from Germany
DC2NI.. jürgen Recker
dc2ni at gmx.de