Change of plans.
Change 1: I switched spindles on Day 2 because the green stone one was a bit heavy for the singles; it kept pulling and I had to grip the fibre too hard to prevent it from slipping apart at the drafting zone. I'll still be plying on the green stone spindle, but I am spinning the singles on this:
Change 2: I have also come to the conclusion that unless I get much, much faster at spinning yarn this fine, my TdF goals are unreasonable.
It took me about 4 or 5 hours to spin either of these (2 grams of 40 WPI thread on each quill). I just don't have that time on workdays, so I've decided to amend my goals to:
Spin every day for at least 20 minutes, aiming for consistency and fineness. I'll take 2 grams of fibre per colour, and each colour will be finished when it'll be finished. This is supposed to be fun, I'm not going to stress about production.
And this is how fine 40 wraps per inch yarn is. I did a calculation, and each strand of 2-ply is about 0.6 mm thick. Zero. Point. Six. Millimetres!
I don't even want to know what WPI the singles are. I am very pleased to have achieved the same grist on both days, but there are still some thicker and thinner lengths in the singles.
More practice is needed, but that's what TdF is for. :)