Thanks,
I'm a firm believer that deep/hyper red is the way to go to ufrther improve our cob builds ...
I'm surprised 4T are still so hard to come by ... wish I could get my hand on some.
... when I search 4T I always end up on this old post of @alesh @SupraSPL and myself from 3 years ago (!) already looking for them ...
https://www.icmag.com/ic/showthread.php?p=6371593
osram apparently doesn't sell by bins, but by batches, so you never know what you get