Semperfli Fluoro Brite

2,30 EUR Incl. 24% VAT
Manufacturer: Semperfli

Semperfli Fluoro Brite is a 3/0 size thread for bodies, hot spots, fluorescent ribbing and hot spot tails. It can also be used as a floss: simply untwist using your bobbin holder to create a flat floss. Recommended for hooks #10 to #2/0 but if you want to use it for smaller flies, Fluoro Brite will split down further for you.

Since Joseph Keen's Book - Fluorescent Flies (1964) and Thomas Clegg's book - The Truth About Fluorescents (1967) fly tyers have been working with fluorescent materials. Today there are different fluorescent flosses available. However the manufacturing quality of such materials can vary with some flosses coming in different sizes from the same manufacturer. This makes it difficult for fly tyers. Semperfli decided to make a fluorescent thread with advantages that it could be used as a tying thread or as a floss, could be untwisted with the bobbin and used as a floss. Fluoro Brite was born to be different.

What is well known is that fluorescent materials do attract trout, salmon and other species. We cannot see material effects except under a UV torch where we see the glow. But with their visual rods and cones capable of seeing into the UV spectrum many fish species see this like a light in the dark.

Fluorescent materials work well one hour before daylight and one hour after nightfall. This is because even though we cannot see them, UV rays from the sun are still being refracted through our atmosphere and helping glow those hotspots.


  • Specifically formulated for fluorescence
  • 25 m spool
  • 240 denier
  • Thread Aught (or /0 sizing): 3/0
  • Recommended hook size #10 to #2/0, for smaller flies split Fluoro Brite to use down to size #20
  • Use as hot spot, fluorescent ribbing, body or hot spot tail
  • For use as a floss simply untwist using your bobbin holder to create a flat floss


Use several strands as a tail, cut and tease the fibers with a dubbing brush. Because Fluoro Brite is twisted you will be left with a stunning, crinkled, fluorescent tail which produces sparkles like fireflies at the end of the tail under a UV light.

Suggested fluorescent color usage from research by Clegg and other fly tyers and scientists:

Color Recommended Usage
Scarlet Very effective at dawn, dusk or dull days or peaty water
Orange & Yellow Best on bright days
Green Colored water and bad light
Luminous White Best 1 hour before dawn and deadly 1 hour before dusk
Pink Grayling any time of day


Blood Red
In stock
Fl. White
In stock
In stock
Green (pale)
In stock
Availability unknown
In stock
Orange (pale)
In stock
Pink (pale)
In stock
In stock
In stock
Sunburst Yellow
In stock
In stock
Add watch

See also these products