Once in a while it happens you accidentally damage your flyline. If it happens on a bush-trip it can really mess up your trip. There are of course many different things that can happen to a flyline, but generally most damages can be put into two categories: 1; Damage to the coating and 2; damage to the core (even breaking the line in two).
Believe it or not both can be fixed with few materials materials that you can easily include in your kit so that you have them with you all the time.
Depending on the extent, damages to the coating are usually quite easy to fix. I have more than once had the leader cut through the coating on a bad cast. This you won't feel in the cast and you can easily fish on for the rest of the day. The problem with this cut is that water will soak into the coating, making it sink and it will break down the flyline a lot quicker than otherwise. This problem is very easily fixed add a small drop of flexible PVC-glue to the cut and allow to dry and you're rolling.
If you accidentally step on the line or get it dragged across a stone by a fish, resulting in a larger area of core being exposed by the peeled-off coating, you'll need to do a little more. If it's a small area, just glue it like above. Add a thin layer and allow to dry. If needed, apply another layer of glue and you're singing. If a larger/longer piece of core has been exposed you'll need to protect it a little more than the glue can manage. With a bobbin holder and thin tying thread (no thicker than 8/0), make a thin whipping of thread to protect the core and finish off with a half hitch or two. Using the same flexible glue, you coat the whipped area with a thin coating to keep the thread-wraps from coming undone and allow the damaged area to pass smoothly through the rings. If it's really bad and a long piece of flyline has been damaged, I suggest you look below and see what to do when the flyline has been torn over because the best thing to do is to simply cut out the damaged part and splice the two back together.
When the core has been exposed, take care to inspect it for damage too any sign of fray or other, I suggest you cut out the damaged section and look below.
Joining two pieces of flyline has already been covered by Lasse Karlsson in his Smooth Connections and I suggest you take the time and use the second method, as this produces a very smooth connection that you won't even feel in the cast (no hinging at all I've been there!).
My Line Kit contains these items.
Scissors or small knife.
Small piece of cloth.
With this set I can repair, clean, fix and lubricate at all times.