Did a search and came up empty so hence this comment. Probably not new to a lot of you but I noticed that black ain't necessarily black even from the same brand. I've been using Gudebrod regular A as underbinding and NCP C as overbinding. During doing the first overbinding is when I noticed that the NCP black is different to the regular. It could be simply the fact that the NCP already has color preserver hence the difference. Haven't put any epoxy coat on it yet as I'm still waiting for my Threadmaster to arrive. Can't get it locally so had to get it from US. Maybe the shade difference aren't noticeable under the finish. Won't know this until I've done it.

Ken, NCP thread has chalk in the dye. Nylon thread is translucent therefore light can pass through it and affect the color. The introduction of chalk in the dye bath keeps light from passing through therefore "no color preserver (NCP)" is required. The chalk will give the thread a pastel or dull appearance.
Regular nylon will be much brighter but CP is recommended in order to maintain the brightness and color of the thread.

Most NCP blacks are not as deep in coloration as the regular nylon version. Some will come off as almost a dark navy blue.

............

i would suggest using regular nylon for both.

Bill - willierods.com

Ken I just did a 15 sample experiment with each black I could find in each size I could find. I have a picture and though it doesnt show as much as the natural eye does it does show there are many variances of Black. I put finish over them with NO CP to keep the blacks as black as possible. CP really chances the whole thing and I recently did an experiment with 7 or 8 different CPs on 4 different colors with pictures of that too. Also did a blind survey at a recent event and talked twenty volunteers to give their impressions. Anyway I digress. If you want I can email you the pictures. I believe my email Addy is open. They arent great but interesting. Seeing them in person really shows what is what.

Ken,
You've discovered why I've switched to metallic black for my black thread. It's a nice black that is always consistent.

TC

TC, I presume you're using HT metallic and as overbinding? The previous metallic thread not strong enough as overbinding according to many?

Anyway, I'm not going to use CP at all as only using black and metallic silver for trim. Didn't know that Gudebrod used chalk in the dye for NCP.

kk