Hi everyone,
This is my first post & I am new to rodbuilding.
I've just rebound a friends surf rod (old mustard
coloured blank, unsure of make/model). I used
Prowrap colorfast - 428 'summer sky' in size "A"
for the underbinding. I noticed a significant colour
change (darkening) when I applied the 1st coat of
finish. Is it common for the colourfast/ncp threads
to darken? Is there anything that i can do to avoid
this in the future?

Thanking you.

Even NCP or Colorfast threads will change color, the lighter threads are more noticeable. However, they won't turn translucent like regular thread. Color preserver is what you'll need to do if you want to keep the color as close as possible. Plus, the color preserver will displace air better than finish

Thank you. I'll give colour preserver a try next time.