I have been exploring some new 100" top-string setups and refining my HEC-based mix (my preferred mix is now 20:1 water:detergent with 2.3 grams HEC -- either Natrosol 250HHR or CelloSize QP100MH) plus baking soda and citric acid.
I have had nice results with a RubberMaid microfiber webfoot top-string and just a single strand of twine for the bottom or a strand of twine and a strand of bamboo yarn. I want try a slightly higher capacity bottom (maybe two strands of twine) with a higher-capacity top.
Here are some vids of this setup:
Here is a giant bubble with just a single twine strand for the bottom.
Here is a giant that I didn't manage to close but which I found beautiful. I have slowed down the bubble so it can be apprecated:
Here it is with a little compositing to help get a better sense of the size: