So far I haven't done what your recommending only because I didn't have the proper batting to work with and cabinet size maybe to small for the curtain. When I installed the flower pots over the midrange the only batting I had was either pink paperbacked 3-4" fiberglass insulation, 1" fiberglass sheets from the X10s, or 1.8" UltraTouch.
All of those materials, alas, are far from ideal for sound deadening in an infinite-baffle application.
The cabinet is small, true, but it is not too small; Bozak sold smaller bookshelf units, like the B-313 and B-502. While those were arguably too small for a B-199 (about 2 cu ft instead of the requisite 5 cu ft), Bozak used a similar padding/curtain layout, just scaled down. It will work, but the bass will not be as low as the larger variants.
I ended up separating the UltraTouch to make it thin enough to use inside the pots. I haven't wrapped the outside of the pots yet. How should I go about that , what material should I use, and is the UltraTouch ok to leave on the inside?
I suggest you discard the UltraTouch in favor of cotton batting. When Biggles had his problems with his B-302 project and was ready to give up, I suggested he replace all of the Ultratouch and move to a swinging curtain using upholstery batting. This completely solved the problems. Others have had similar results.
The core issue here is that UltraTouch is far too dense and has no loft. I cannot say if this is a consequence of the factory compression for shipment, or inherent in a ground-up cotton instead of fiber approach, but it is a problem.
Since UltraTouch is a dense mass it lacks interior voids crucial for sound deadening. It really is totally unsuitable for damping on a speaker cabinet, particularly an infinite baffle cabinet requiring a loose curtain . Again, Biggles will confirm this for you, as will others who had similar experiences.
I just received the 1" natural cotton upolstery batting yesterday. I replaced the X10s original batting on one speaker for a comparison. I fed them a mono signal and swung the balance back and forth. I couldn't hear any difference at all. Then I got in between both speakers and turned them to face me, I still can't hear any difference. I'm wondering if adding a curtian and wrapping the outside of the pot will have any effect.
The curtain is a key part of the Bozak infinite-baffle cabinet.
The outside of the flowerpot is less critical, but the goal is to remove all interior reflections and ensure the backwave is lost. This is why Bozak covered the crossover with a piece of batting. Many times these interior reflections will result in resonant peaks which cause non-linear behavior that degrades the quality of the audio, anywhere from suble to substantial.
Maybe I don't know what to listen for. Anyway the distance between the midrange pot and the insdide back cover is only 4.5" minus 2" for existing batting and that only leaves 2.5" for the curtain.
The short distance likely does not matter because it is at the top. As long as the curtain remains free to move, all should be good. The pressure waves will migrate around it. The point is to lose the backwave so it can't bounce off the sides and rears to return. That's what the curtain does.
So far I can't hear any difference between the different batting.
I suggest re-creating the interior of a B-302 and repeating your testing.
Using software which will generate an SPL plot may show you details which you cannot easily distinguish by ear.