A fanstic know for tying two lengths of nylon together, the blood knot can also be used as a dropper if it is tied with the tag end of the length nearest the fly line left long.
The Blood Knot is a commonly used knot for joining two lengths of nylon e.g. when making up leaders. The Blood Knot was named after its inventor and practice is required to master the technique.
Cross either end of nylon about 100mm from the end.
Hold a crossing point between the thumb and fore finger of one hand. Using your other hand, make five turns of one line around the other. Pass the end of this line between the crossover point of the two lines.
Switch hands and hold the crossover point with your other. Make five turns with your free hand, but making sure it is from the opposite direction.
Moisten the knot and tighten it slowly, pulling on the main lengths of nylon to achieve a secure knot.
Trim off the tag ends and you’re done!