Merging fly lines with shrink tubes

Published Jun 8th 2014

Neatly melting together two lines


Practice on an old fly line or a cheap line. The first few times you might fail, but when you get the hang of it, its quit easy.

This is only a start-guide. There are many variants of making loops with shrink tubes. Make your own experiments.

Merging Two Lines
Below is a step-by-step guides showing how to make merge two lines. The method is universal for all coated fly lines and makes it possible to make you own WF-lines, smooth connections and more.

Step 1 - Insert your fly line into a piece of shrink tube af approx. 6-8 cm (2-3 inches).

Step 2 - Heat the tips of the fly lines.

Step 3 Remove the coating.

Step 4 - Now the fly lines are ready to be merged.

Step 5 - Sew the core from each fly line into the center of the coating of the other fly line..

Step 6 - (optional) Before pulling the lines tight together, apply a bit of glue.

Step 7 - Pull the fly lines tight together (before the glue dries out).

Step 8 - Cut of the tag ends of the cores.

Step 9 - Place the shrink tube over the merged position.

Step 10 - Apply heat to merge. The coating should merge to the extra core inside.

Step 11 - Remove the used shrink tube.

Step 12 - You have now merged 2 fly lines.

Tip 1:
This will not work on all fly lines!
It works better on floating lines than sinking and not on fly lines with a mono core.

Tip 2:
You can color code your lines by adding a small piece of coating in a different color under the shrink foil before welding. It requires some practice but the result is overwhelming.
Of course you can mark the line with markers before welding. However, this will fade over time.

This guide is made by Michael Sorensen from Innosoft, check out his fish condition calculator app here.

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