I am not sure if anyone has come across this but recently I have been doing twisted 32 coils in a variety of small chamber atty's with Rayon and found that after wrapping and test firing them the coils shrink a bit, you can actually see it 1st fire. I thought this may be of interest due to having to get rayon tighter in coil. I think this may have something to do with people saying wick seems to be breaking in. I have been watching this on the last couple of dripper coils i did and after a short time ,wick that i thought was to little or lose in coils appears to be much tighter than initial build. I have only seen on twisted 32 as i havent tried on larger gauge yet.
Just my input and 2 cents
Coils most the time contract closer together on Initial firings. I always dry fire a coil multiple times and heavily glow it. Each time I insert the mandrel when I let off while its glowing. This sets the shape. I may do this 5-10 times and by the last a long glow at the highest power will not change the coil. It will remain after that.
Rayon does reduce in size for the first 3-4 ml. When density is spot on it will have no taste break in and will not loose contact after the reduction.