Final Update.
I give up.
After 600C not doing the job (but an interesting development I discovered next morning - more on that below), I tried out a mind-boggling 640C. Which also failed, essentially for no other reason except it's a ridiculously excessive setting for the sake of a lousy 520 degrees Celsius. Unless little spacer beads are all you make. They turned out just fine. But I generally make bigger focals and sculptures more than little spacers. Most of my big focals are squished somehow, but I also make fully roundy ones which require more soak time.
Five weeks of almost continuous testing, every which-way including 'upside down', this little beast has beaten all the fun of lampworking out of me for a while. And I couldn't be madder. Or sadder
As for Paragon's claim of BE film giving a more accurate result than sunglass lenses, well I'm very sorry to hear that because it's quite true. But more damning. See pic below.
As for the little surprise from the 600C batch firing, well I could have been knocked over with a feather.
The distribution of heat in that collar is, IMO, incredibly uneven.
I had the batch beads kebabbed on bare mandrels and propped in a rack. One mandrel was in an upper rung of that rack a couple of centimetres higher, and the little spacer above the focal (opaque focal, unfortunately or I would have checked it) had tacked itself ever-so-slightly to the focal. WTF??
But beads below that focal (2-3 to a mandrel with a spacer at the top) were not annealed, despite the decent reading (510C) from the analogue at the bottom. Something is going on above the floor of the annealing collar where the temperature changes quite markedly. This firing was a slow ramp up, and two hours soaking of focal sized beads. Way above annealing temperature at one place, not enough (or not for a long enough time) in another. And really if a bead was going to tack fuse, at that controller temp, it should have also stuck fast.
Given the analogue reading (510C) for that firing one hour into the soak, all but the very biggest should have been annealed, but even the smaller beads further down the kebabs weren't. There was plenty of time for at least the 15mm and smaller beads. 3 hours for the 20mm beads would have done the job, but who knows what the hell is happening in that chamber? And what on earth could it do to silver and other reactive glass beads with a weird distribution or movement pattern going on in there?
The 640C firing was a garage session, in which all beads were soaked for at least a full hour, while the largest were soaked for the full two hours after being made during the ramp-up.
Granted, they could have done with another hour, or more, but really, who would sit next to a kiln blazing at 640 degrees for that long?
My sessions would typically last up to six hours at a time which is fine when your big brick kiln is running at a nice 510-520C in the far corner of the shed.
I bought this little one to have within a table's distance in order to just plonk them through the hole. That's great if you can stand to be in the same room with it for hours at a time.
Even then with all stuff I've just written (by all means challenge my findings, I don't mind at all, and the variables are huge, I have to concede), my issue is still that the stated schedule suggested by the manufacturer, and the way it's worded, is enough to fool anyone who doesn't have the means (or inclination) to test for strain, into trusting they've bought something which will do the job out of the box.
My conclusion is that I'm sorry, but it doesn't, in this instance. We place a lot of trust in manufacturers when we should be trusting our own investigations more.
There's no way I could trust this kiln to do a good job. I'm too old and too tired to have to be testing for all the types of work I do every time I sit down to make beads. Hell, all I've been using is plain ol' Effetre transparents and scrap clears.
Bugger effing around with my BE or boro all over again!
I'm done with this kiln, and with Paragon. They have treated me appallingly and I'd never ever recommend them to a new kiln buyer.