How Metal Tone Rings Can Choke Tone

Ever since Gibson created their cast tone ring in 1927, it seems that heavy metal tone rings are still all the rage. However, in many case these heavy metal tone rings aren't giving their full potential because they are fitted tightly. After all, Little Roy Lewis once got his hands on Earl's banjo at the Gibson factory, and he said that Earl's tone ring was so loose-fitting that it could easily be spun.
So why would Earl want his tone ring to be loose fitting?
I, along with many others, believe that the wood of any rim (whether it be a 3-ply or block) can swell with humidity and moisture, causing the tone ring to become tight-fitting, or even tighter than it already was. In order for the tone ring to work as it was designed, it needs to be able to vibrate. If the wood has swollen and caused the tone ring to become tight-fitting, then it can't vibrate as it's supposed to, and therefore, tone becomes choked out.
A good friend of mine and fellow banjo builder cut a block rim to fit a flathead tone ring. He fitted it so it was a slip fit. He then took this rim to his basement, which is a moist environment. He came back the next day, and the wood had swollen to the point that he couldn't get the tone ring back off the rim. So he then took it outside and allowed the sun to hit on it for a while, and after the heat had a chance to draw out the extra moisture, the tone ring came right off, just as loose as it was in the beginning. 
He then took an opposite approach. He took the very same tone ring and put it in his refrigerator overnight. The next day, he found that the inside diameter of the skirt had shrunk by 30 thousanths of an inch! He tried to fit it on the rim, and it wouldn't even begin to fit, and even after 24 hours at room temperature, it didn't fit like it did before.
These things in mind, have you ever played your banjo outside on a foggy night? Did it sound sort of choked? Like it was missing something? I have, and so have many of the musicians I know. It's no fun when you know your banjo sounds great, but then when the moisture levels in the air are really high, that banjo just doesn't put out like it should.
Don Bryant of North Carolina started using these cast tone rings without a skirt. Since there isn't a skirt, there is nothing for the rim to swell and tighten against. Therefore, there is nothing to choke the tone of your banjo. Once again, my friend tested this by cutting the skirt off of one of his tone rings and building a banjo around it. I have played this banjo, and it sounds better than any tone ring banjo I have ever played (and I've played a number of high-quality tone ring banjos). 
Now take a woodie or brass hoop banjo: in my experience, these banjos do not come and go with moisture and temperature like skirted tone ring banjos do. Obviously, they do change slightly, as it's natural for wood to do so. However, I have played woodies and brass hoop banjos in moist conditions, and they loose no tone. In fact, they sound basically the same each time they come out of the case.
Knowing these data and test results, I here at Lemon Banjos will not build a banjo with a skirted tone ring unless the customer asks for it. All of my standard models come with either wooden tone rings or a brass hoop.