The glass on my Bullet fell out while I was doing a deep clean. I inquired Allio Bullet regarding their recommended sealant. They said they use Dowsil 732 multi-purpose sealant. In their email they noted that this silicone glue could withstand up to 180 degrees C with short peaks up to 205C. This raised a big question in my mind because I often preheat to 554 F, so I questioned them about it. I also wondered if my using Urnex Sprayz had anything to do with the glass falling out while cleaning. I got a very helpful reply, as follows:
" Hi Jonathan,
Thank you for your reply. Regarding your question, I would like to explain the IBTS Preheat Temperature. For this, we must bring the IR Sensor with Germanium Glass Module system into the discussion.
IR Sensor with Germanium Glass Module:
Designed to measure the Drum Temp.
IBTS Module:
Designed to measure the Instant Bean Temp, while also doubling as a drum temp sensor during preheating.
As shown above, the recommended preheat temperature for an IBTS-equipped Bullet is higher than the previous germanium glass version. For 750g beans, the V2 recommended preheating setting would be 527ºF - 590ºF, while only 365°F - 401°F for V1.
It is the inherent difference between IBTS and the old Germanium glass design. The surface texture of the materials IR detects would greatly affect its reading, so every IR sensor needs to be calibrated according to its purpose. In the old germanium glass system, the main purpose of the IR is to detect the drum temperature, which is metal.
On the other hand, IBTS is designed, calibrated, and optimized to read the instant temperature of the coffee beans. Therefore, the reading it gives out when measuring the drum is higher because of the material differences. As a result, the preheat temp of the IBTS module needs to be set to a higher number.
When you preheat the bullet to 554 degrees Fahrenheit with the IBTS, the actual temperature of the drum is more likely around 360 F, and the temperature around the door glass would be much lower, and the glue we are using can hold up with that.
On the other hand, if the downward force applied to the door while closing it is too great too frequently, the glass would come off more easily. Using Urnex Roaster Sprayz should be fine.
Hope this helps!
– Matt Yau"