Just to give a little data to this thread/topic and to see for myself if there is a significant difference in the behaviour of Bios in wet conditions or a difference between the behaviour of Bios versus Non-Bios, I put a small sample of whatever I had in the house into ziploc bags of water following my last post so these are figures based on the sample BBs being completely submerged in tap water for 18 days (it was night time so I'm counting only whole days).
Following the submersion, I measured five BBs from each wet sample and five BBs from the original dry source bottle/bag. I don't have a massive selection and most of those are Bio so I don't have a great control group of non-bio BBs to select from.
So, the hypothesis tested is that Biodegradable BBs swell out of spec on absorption of moisture.
The attached table is a summary of the results and I think the conclusion I first draw is that there is no absorption or swelling of BBs after nearly 3 weeks underwater.
The variation within samples appears greater than that between wet and dry in most cases. Also, I am pretty happy with my standard choice of Nuprol RZR 0.28g Bio 😉
There are obvious limitations to the test, primarily in that the sample sizes are small, I can't be fussed expanding the test but I'd be more than happy to applaud anyone who wanted to, I am happy to email the full data table with individual measurements, if anyone is that bored on lockdown. Another possible source of error is the measurement equipment, I used my general garage micrometer to do the measuring, it doesn't have a valid certificate of calibration and it has a stated precision of 0.01mm so the variation seen in most samples falls inside the possible error of the test equipment.
Thirdly, this isn't a blind test, I knew what each sample was and so there may be subconscious bias but I doubt it.
I really hope this lockdown ends soon, I clearly have too much time on my hands.