Annealer Manual


    • KSU Glass Studio Annealers are equipped with an Interlock System which sense when a door has been opened and instantly kills electric power to the elements. This prevents the possibility of electric shock in the event a user accidentally touches an element while loading or servicing a kiln.
    • The annealing temperature of the glass type used at KSU Glass is roughly 960˚F. Proper safety gear must always be worn when working inside a hot annealer—face-shield, Kevlar gloves and fire-resistant jacket are standard. Always wear the face-shield when putting hot glass pieces into an annealer! The shield allows the user time to deliberately and carefully place the work in an appropriate place. More importantly, the shield will protect the user in the event a glass piece violently cracks or fractures and sheds glass shards (in essence explodes), which is a common occurrence when working glass at annealing temperatures.
    • Best practice for Studio Glass is to work with a partner. A partner is hugely important when transferring a finished work to the kiln for annealing. The practice of simply “breaking it off the puntie” into the annealer is crude, indelicate, and unsafe.
    • Always load work from the back of the annealer to the front. Never place a finished piece of glass right in front of the annealer unless an annealer is full. Loading from back-to-front means other students won’t have to reach over your work (potentially damaging it) to put away their work. Loading an annealer properly is a sign of good work ethic and professional consideration.
    • It is not a good idea to get into the habit of reaching into an electrically powered kiln with a highly conductive steel rod, even though we have redundant safety “kill-switches” that kill electric power to our Annealers when a door is opened. Should our system fail, the user would be in danger of receiving a very dangerous and substantial electric shock. Of course, with redundant safety systems this is very, very unlikely to happen, so of greater concern is the habit itself.
    • Have your partner put on the Kevlar gloves and shield and take control of the finished work for you. Habits formed in an academic setting get transferred to the professional sphere and it is important to learn good, safe practice from the beginning.
    • Annealers need to be kept clean of dust and broken glass. This not only keeps finished work from being scratched or picking up dirt when put away, but also keeps you safe when emptying an annealer.
    • After emptying an annealer sweep and/or vacuum glass shards from the interior.



    • The “EZ-1” Buttons send annealers up to annealing temperature: 960˚F.
    • NEVER Press EZ-1 unless you’re sure that:
      • The Annealer is empty.
      • The Annealer is Clean.
      • The Annealer doors are properly closed and the Interlocks engaged—indicated by a blue light in the “Interlocks” light next to each controller.
    • After pressing the EZ-1 Button you should see the EZ-1 light come on in the right column of the display AND the “Profile Icon” should also be illuminated.
    • If you press EZ-1 and nothing happens, wait a few seconds and press it again. If there is still no response then alert an Instructor, Grad, Tech or Senior student. If none of these are available (e.g. if you’re Opening the Studio and can’t immediately contact someone by text or phone) then send up another Annealer.

    • EZ-2 sends the annealer down into “slow-cool”/annealing mode.
    • Never press EZ-2 until:
      • The annealer is full and can’t fit any more glass.
      • Or: the Studio is Closing and there is another Annealer available for the next day. (In the event that both large annealers are on and one Annealer is half-empty and the other is full, only send down the full annealer. That way there will be space for students working early the next morning.)
    • Unless you’ve been properly trained you should NEVER press any button other than EZ-1 or EZ-2.
    • If you accidentally press another button immediately press the Infinity Button (∞) until the display shows the two temperatures (red on top and green below); this means you are out of program mode and back to default screen.


Watlow controllers combine the ease of a simple thermostat with the sophistication of a programable kiln controller. However, they are based on a completely different set of parameters than Digitry™ (GB-4) controllers. Most notably, you don’t need to run a program to turn a furnace or kiln on or off, or raise or lower the temperature. Programs are useful, because they can turn a kiln (or furnace) up or down over a specified time without you being there. However, we can simply use the AUTO function to manually set the temperature, just like your thermostat back home. For example, if a kiln is at room temperature and you turn it on with the Set Point at 960°F (Annealing Temp) then the kiln will ramp up to that temperature as fast as possible (AFAP), no program needed.

This is the simplest way to run our controllers, but it’s also the most primitive. It allows for simple ON/OFF programs, and you can’t anneal thick work or slowly heat up a delicate glass component for a hot-sculpted piece.


That’s where programs come in.

The advantage of the Watlow is that it can run a furnace charging profile, a glory hole, an annealing or casting kiln. In the past glass studios have relied on separate types of controllers to run Annealers, Furnaces, Flory-holes and Casting Ovens. This made for confusion and redundancy, since the user had to be familiar with several operating systems in order to keep a glass studio running. This means more cost in operation and maintenance.

One of the major differences is that unlike the traditional Digitry™ GB-4’s, the Watlow does not use cumulative time. This means that you can very easily jump to any step in a program and change it without affecting any of the other steps. (For example, if you programmed your kiln for 3 hours at casting temperature—1500˚F—but aren’t sure the glass will fill the mould completely in that time, you can easily jump to that step and change it.) In essence, each step is a stand-alone piece of programming.

Another difference is that it is very difficult for someone to accidentally forward a Profile (program) to the next step while the kiln is running. This has always been a major drawback of the GB-4 controller: it is far too easy to accidentally send a Profile to the next step and inadvertently damage a casting or large blown piece. However, it takes several complicated steps to do this with a Watlow.

You’ll also notice that each Watlow controller is assigneed to an individual piece of equipment (furnace, casting-kiln, annealer, etc). Again, this is a safety feature that reduces the chance that someone will accidentally tamper with a Profile while a kiln is in use. On Digitry’s GB-4s, each controller can run up to 4 pieces of equipment, so it’s fairly easy to tamper with the wrong kiln. But, the Watlow™ controller should drastically reduce unfortunate incidents, especially in a community studio setting where a lot of users and interacting with a controller.

The KSU Glass Studio’s Watlow Controllers have a few other unique features. Most notably, they have been individually programmed for their designated use. For example, the Blowing Annealers (B1, B2, B4 and B5) are programmed not to exceed 1000˚F. This is to ensure they cannot accidentally be sent past annealing temperature and slump or melt the glasswork inside. Casting Kilns, on the other hand, are programmed with a max temperature of 1600˚F (although we rarely exceed 1550˚ in most casting scenarios).

So, if you need to preheat a piece of glass to be worked hot—for example a “stuff-cup” or thick murrini—you should use the top-loading Pickup Oven: B3, which has been programmed to reach 1200˚. If your object is too large to fit into that kiln, we have the small, front-loading Wet Dog annealer (B4) that can be programmed for such use by an Instructor or Grad-student. You’ll need to let them know ahead of time, reserve the kiln for that use and be sure it is returned to normal operating parameters after use.

Another thing to note is that the Watlow™ controllers are not tied to the safety (Interlock) system. That means that the controller will continue to run a profile, regardless of the Interlock condition. Simply put, it doesn’t matter if the door to a kiln is open or closed, if you start a profile, that profile will begin running. The Interlock doesn’t communicate with the controller, it simply kills electric power to the elements inside the annealer or kiln. So, if you start a profile while the doors are open, the profile will begin running even though no power is going to the kiln. Here’s an example, say you’ve programmed the Pickup Oven to preheat a glass part over 4 hours to 1000˚ but you forget to close the door until 3 hours later (perhaps when you come in to prep for your blowslot and noticed the door was open). Well, when the door closes power is then sent to the elements and the Watlow recalculates, it will now send the kiln up to the Set Point (1000˚) in only 1 hour (because 3 hours have already elapsed). The controller only knows what you program into it, which was “go from room temp to 1000˚ in 4 hrs”. It doesn’t care that it wasn’t getting hot for 3 of those hours, it only knows that after 4 hours it has to be at 1000˚.


  • Annealer: Electrified, insulated container for the slow, controlled cooling of glass for the purpose of removing stress.
  • Controller: Watlow controllers located in grey control panel located in Class Room. KSU Glass Controllers are equipped with EZ-1 and EZ-2 capability, which facilitate 1-touch operation of Annealers. (see Watlow Controllers below).
  • Elements: High-temperature, resistant wire coils which power most Annealers, Kilns and Ovens.
  • EZ Button(s): Watlow controller button that allows user to run a profile with the push of a single button.
  • Interlock: Safety switch that senses when Annealer doors are open and kills electric power to the Kiln. (These are small silver tabs on front of KSU Glass Studio front-loading Annealers and indicate that doors are properly closed (and power on) with a green light. If light is off then door is open and no power is going to the Annealer. (See Preventing Glass Breakage and Safety below)
  • Kiln: Interchangeable with annealer but refers more commonly to equipment for casting glass. The term Oven is also used. (e.g. Casting oven or casting kiln or annealing oven.)
  • Profile: A program/series of steps inputted into a controller.
  • Set Point: The temperature the controller is set to attain and/or hold. (e.g. Annealing temp: 960˚F)