Does all the thread dry so dark after the finish is on? I have a few rods to repair how do i take the old finish off?

Just depends on what you did.

Did you use NCP or nylon thread?

Did you use CP (color protector)?

Removal... heat it up LIGHTLY with a lighter, slit it along the guide foot using a razor blade, pull wraps off.

You way want to look at rodbuilding.org... lots of info.

I used gudebrod nylon without color protector

if you don't use CP, it will all change (except metallic threads) but not always darker.  I always make a set of test wraps in between guides and wet them.  Spit will give you about a 90% accurate look at what finish will do.  Just be sure to saturate the test wrap and wait a minute for it to really soak in.

As for removal of old finish, be sure to only use a razor on top of the old guide foot so you don't damage the blank.  A hairdryer is better than a flame until you get a feel for it...  you just want the old finish warm, not hot.  Lots of new people have ruined rods with lighters.

NCP (NoColorProtector) thread doesn't require the use of CP. The idea here is it won't change color once you apply finish. I've had NCP change color though... :-/

Yellows, whites, tan, etc (light colors) usually have to have a silver underwrap or coat of white paint under to really maintain their color on a dark blank, even when using CP.

You will also find several CPs on the market will darken the thread color on nylon thread. This is before you ever apply the finish. It's not a huge amount, but it happens. Best product I have seen for maintaining color is ChromaSeal. A little more $ but it's worth it. I really haven't seen a lot of darkening when using it. My next CP choice after that would be flex coat or U40.

Nylon with no CP will turn translucent - not just dark. This isn't always noticable with black, dark blue, etc - but it does go "see through". It can make for a pretty cool look. You see the guide through it, etc. Perfect example... Cobalt blue nylon with no CP on a blue SCIV blank... can't even see the thread hardly.