I can speak from years of mistakes, reading too much and believing all of the wrong things.....
My quick advice:
1- It really does depend on what finish you are using. As Garone mentioned, if the threads are covered, its enough. Some brands need to be coated again before the initial coat is fully cured. If you go over the top of a cured coat, it will cause cracking and allow water underneath the wrap, resulting in that white, milky look that we often see.
2- Thread is the key here. If you over wrap, or wrap too tight, you will block the finish from fully penetrating the wrap and making it to the rod blank itself. This is also trouble down the road.
Think of the thread as re-bar, that holds something in place, until you pour the concrete. If you have too much re-bar, the concrete does not make it to where it has to go. SO be careful not to over tighten the wraps. It goes against what you would think, but its true.
3- Keep the wrap within the same lot of finish, if your using multiple coats. Although its the same brand, you may have a different lot and the 2nd or 3rd coat can cause an issue if the mix from the manufacturer is off.
There is more to wrapping rods than most people think. A proper wrap should last a lifetime and with today's UV protected finishes, not fade more than maybe 15-20%. If you have any questions, feel free to contact me or post them up.
I use 2 coats on all of our rods. But as I said, years ago I ran into problems and had to learn the hard way. Sometimes the smallest thing can cause the biggest problem.
This applies to coating the under wrap, before wrapping the guides on, too. You want to be careful with that. If the epoxy is not right, you will have an issue between the top coat and the under wrap coats.
