14 July 2018

The Color Purple

Did you know that Purple was the 2018 Color of the Year?

Specifically, the chosen hue is PANTONE 18-3838, most commonly known as Ultra Violet. That's interesting... because, by definition, actual "ultraviolet" light is invisible.

"Each color of the year encompasses something about fashion, decorating and design trends while also reflecting what's needed in our world today," said Pantone Color Institute's vice president, Laurie Pressman. Last year's color of the year was a "life-affirming" shade of green. The year before, it was a pairing of rose quartz and serene blue that was seen as "anti-stress".

So, what does Purple have to say about our planet in 2018?

According to Pantone, Ultra Violet is a dramatically provocative and thoughtful purple shade that communicates originality, ingenuity, and visionary thinking, all of which point us toward the future.

Historically, mysterious purples have been symbolic of unconventionality and artistic brilliance. Musical icons Prince, David Bowie, and Jimi Hendrix brought shades of Ultra Violet to the forefront of western pop culture as personal expressions of individuality and creativity.

There has also been a mystical or spiritual quality attached to Ultra Violet. The color is often associated with mindfulness practices, which offer a higher ground to those seeking refuge from today’s over-stimulated world. The use of purple-toned lighting in meditation spaces and other gathering places energizes the communities that gather there and inspire connection.

So, whether you're a lover of Purple Rain or Purple Haze... it's time to crank up the volume and get creative!

08 July 2018

Peepholes and Venting

Last week, we got an e-mail with a bunch of great questions about peepholes and venting your kiln when using powdered enamels dry on copper. So, we thought that we would give you some insights on venting for all kinds of enamels on glass, and metals too. Hopefully, this Q&A from Gail will help you in the future... it always helps me!  

Why does my kiln have a Peephole?
Large peepholes (viewports), tapered for a wide view without heat loss, were originally designed for manual kilns so you could see when the pyrometric cones bent. With venting as their secondary function, peepholes allow oxygen to be drawn into the kiln’s chamber and serve as an escape passage for metal oxides, smoke, and water vapor.

Do I need a Peephole Plug?
Peephole plugs are used to stop air from entering the kiln, not to prevent heat loss. But a kiln shouldn't be vacuum sealed, so It is beneficial to have some air entering the kiln at all times, It is not necessary that the plugs fit tightly.

What is the best shape for a Peephole Plug?
Peephole plugs are typically made of a lightweight ceramic material that can handle thermal stress well. Many plugs are interchangeable with different kilns, and the type of plug that is chosen is typically based on individual preference. The plugs with a tapered shape are designed to fit in just about any hole.
 
Should I leave the Peephole hole open or closed during firing? 

For plain old glass fusing and slumping, always fire the kiln with the plug in the hole as it helps the kiln reach temperature more easily. If you chose to leave the peephole out during firing to improve the oxygenation inside the kiln, be aware that this may cause a cold spot in the kiln.
  • When firing dry enamels on copper, leave the plug in the hole until you reach the top processing temperature, then remove it for proper oxygenation of colors as you insert your trivets and fork. When you are firing red, orange, or yellow enamels you should remove the plug so that more oxygen circulates in the firing chamber, keeping the colors bright. 
  • When firing liquid enamels on glass, leave the kiln vented or plug out until your reach 1000F. Then place the plug back in the hole. SOME (not all) liquid enamels need oxygen to develop to their juiciest potential!
  • If you want the kiln to cool faster, remove the plug. 
  • If you are doing a wax burnout, remove the plug. 
  • If you are doing a hollow core metal clay project, remove the plug.
Are there fumes that come out of the Peephole that I should be careful of? 
That depends on what brand of enamels... SAFETY FIRST! OLDER ENAMELS MAY CONTAIN LEAD THAT CAN BURN OFF IN THE TORCH OR KILN and will require proper ventilation of the area. Always do your research on enamels before you plan to use them.

                                01 July 2018

                                Observing a Kiln During Firing... What's Normal?

                                A big thank you to our friend Arnold from Paragon Kilns who helped answer these important questions about observing your kiln during firing. Gail also added some nuggets of information to help round out your knowledge!

                                The heating elements hum when they turn on. 
                                The sound is generated because the elements vibrate in the brick grooves due to magnetism between the coils. So, it's totally normal! The sound actually diminishes as the kiln gets hotter because the elements soften. Notes from Gail: This is also true in kilns with suspended quartz wrapped tubes, but it's harder to hear since the elements are inside the tubes. Elements that are wrapped around ceramic rods probably won't hum much at all.

                                The clicking noise of an infinite switch-operated kiln is also normal.
                                It is the sound of an infinite control switch cycling on and off. When the clicking turns into a popping noise, the switch is probably about to fail. Notes from Gail: This isn't happening if you only have a digital controller. But, some kilns have an infinite switch in the lid with a digital control of the body. You'll be hearing the clicking on those.

                                Digital Relays are another source of clicking.
                                To turn on the elements, a digital controller sends twelve volts to the relays. The relays, in turn, act as switches and send full voltage to the elements. The relays click every time they turn on. A chattering noise, however, indicates that a relay is about to fail. Notes from Gail: This is why I'm a big fan of MDRs (mercury displacement relays) and SSRs (solid state relays.) They are much quieter and worth the money to upgrade in the long run!

                                A crackling noise followed by a loud POP from the kiln's switch box usually means that a loose electrical connection has just failed.
                                If you hear crackling, which sounds like sparks, turn off the kiln. The loose connection creates a tiny electrical arc, which overheats and burns electrical parts. Rapid arcing causes the popping noise. Whenever you change elements or have the switch box open for any reason, check all of the wire connections. Make sure they are tight... The power must be disconnected, of course. Tug on the wires. If a wire pulls out of a terminal, replace the terminal with a new one using a good crimping tool. Remove any dust before closing the switch box. When you replace elements, make sure the connections are tight. Notes from Gail: This happens in clamshell kiln lids occasionally, since the lid is constantly being opened and closed, the element connections an get loose. Don't despair, it's an easy repair.

                                Why is there a gap between the kiln and the lid near the hinge? 
                                The gap under the lid of a cold kiln at the hinge is normal. As the kiln heats up, the firebricks expand, which causes the body of the kiln to grow taller and close the gap. The gap is designed to help prevent the front of the lid from rising at high temperatures. Notes from Gail: Yup!

                                The lid on my kiln is rising at the front during firing. What is the cause? 
                                During firing, the wall bricks expand. This pushes the lid upward. If the hinge does not have sufficient play, the lid will rise at the front. If this happens, please do not put a weight on the lid to hold it down. That will only damage the lid. Instead, check for binding in the hinge. Notes from Gail: If this is happening, call the kiln manufacturer and ask them how to mitigate the problem. They'll walk you through an easy fix for your type of kiln. If this becomes extreme, it can crack your kiln lid so, it's important to take care of this issue sooner rather than risk a messy, crumbling lid.

                                My front-loading kiln has a gap between the door and the firing chamber. Is that normal? 
                                There should be no gap between the door and the firing chamber at the side toward the door latch. There should be a gap, however, at the hinge side of the door. When the kiln is cold, you should see a gap of about 1/16 between the hinge side of the door and the firing chamber. As the kiln heats, the firebricks expand. Without a gap, the door will bind at the hinge and cause a gap at the side toward the latch. Notes from Gail: Some kilns have gaskets that fill the space and seal the door opening. If you have a gasket that is worn, it's easy to get a replacement from the manufacturer and should help alleviate the issue. New doors can also be purchased if needed. 

                                I am concerned about the light that appears under my kiln lid during firing. 
                                The light that you see under the lid is normal as long as the lid is not rising in front. The inner lid surface expands more than the outer cooler surface. Therefore, it bows inward slightly toward the firing chamber. This is normal. For this reason, you will see a thin line of light around the lid since the lid is no longer a flat surface resting on the flat firing chamber sidewalls. Surprisingly, there is very little heat loss from around the edge of the lid. Notes from Gail: If you suspect this is causing a cold spot during firing, call your manufacturer. If this becomes a serious issue, you can purchase replacement lids at reasonable prices for most top loaders. 

                                24 June 2018

                                The Firing Stages of Glass

                                We get lots of questions about the overall firing process... fast or slow, open or don't open?  We also understand the anxiety that accompanies firing your kiln for the first time or, trying a new technique. Don't forget, we are glass-a-holics just like you... and, have had a few missteps along the way. With that said, here is a quick look at the stages of firing.  So, the next time you have a question... hopefully, you will have the answer!

                                Initial Heating from Room Temperature (room temperature to 1200°F range) 
                                During the initial heating, the glass is very brittle and susceptible to breaking if it’s heated up too quickly. Imagine a large notebook laying flat on a kiln shelf, it has a top and bottom surface and four sides. The book also has interior pages... basically, anywhere between the exposed surfaces. If we heat the book... or glass too quickly, the surface area will expand faster than the interior of the glass. This is what creates tension within the glass and, breakage... a.k.a. thermal shock! So, during this stage, it’s best to take a super conservative approach and slowly heat up the glass.

                                At the end of this temperature range, somewhere between 1150°F to 1200°F, it’s a good idea to add a heat soaking period to allow the project to equalize to the same temperature throughout. Never peek in the kiln during this stage, or you increase the risk of your thermal shock breakage.

                                Process Heating (1200°F to 1500°F range)
                                The glass becomes softer and more fluid. During the process heating stage, the glass can be fired more quickly to the target temperature and soaked only long enough to achieve the desired look. It’s important not to hold the project at these temperatures for a long period of time, or you run the risk of devitrification (a visible clouding of the glass surface due to crystallization).

                                Fast Cooling (1500°F to 1100°F range) 
                                After the finished look has been achieved, it’s important to cool the inside of the kiln and the glass as quickly as possible to stop the firing action so that it “freezes”. During the fast cooling stage, the surface of the glass is cooler and it has contracted more than the heated center which remains expanded, thus introducing stress into the glass piece.

                                Annealing (1100°F to 700°F range)
                                At the beginning of the annealing stage, it’s necessary to heat soak the glass for an extended period of time to allow the glass to equalize in temperature throughout and release the stress that’s in the glass. This makes the glass more stable. Then the glass is slowly cooled through the annealing temperature range to better ensure the glass piece is free of internal stresses and is physically stronger. NEVER OPEN THE KILN DURING THIS STAGE! I repeat... NEVER OPEN THE KILN DURING THIS STAGE!

                                Cooling to Room Temperature (700°F to room temperature range) 
                                After the glass temperature has cooled below the annealing temperature zone, the kiln can be turned off to allow it to cool at its own pace to around 150°F – 200°F. Again, to avoid thermal shock, do not open the kiln until it has cooled down to at least 200°F. Even at this temperature, the glass is very hot, so do not attempt to pick it up in your bare hands. It may look cool but, it's hot! Simply open up the lid of your kiln and allow the glass and the kiln shelf to cool down to room temperature.
                                Together they comprise a single firing cycle (room temp to room temp).

                                The Bullseye Glass TechNotes 4 is also a very helpful resource for the explanation of Heat & Glass, as understanding the behavior of glass within these different temperature ranges will ultimately be the key to your success!

                                17 June 2018

                                When the Kiln Lid Flakes...

                                Great information about kiln lid flakes from our friends at Paragon...

                                At Paragon, they coat the inner lid surface of all kilns to reduce brick dust. Sometimes the refractory coating is too thick so, it will blister and flake off when the kiln is fired. An especially thick coating looks like a network of peeling cracks similar to a dried mud puddle. This cracking is due to the difference in expansion between the firebricks and the coating. Conversely, correctly applied kiln coating will look like it disappeared after the kiln has been fired.

                                The good news is that cracked lid coating is easy to repair. Just lightly remove the blistering coating with sandpaper and apply a new coat of Liquid Kiln Coating. Keep in mind that the natural tendency is to apply too much lid coating because it just looks better than a thin layer.  If done correctly, you should still be able to see the firebrick pores under the coating!

                                First, shake the container very well! Then, pour some of the coating into a bowl. Make sure to stir it just before you apply it to the firebricks. Apply the coating with a large, soft sponge. Moisten the sponge with water; then squeeze out the excess... this is a very important step! Dip the sponge into the bowl of kiln coating. Wipe the coating over the lid surface.

                                Do not let excess coating run into the element grooves of the kiln. Applying a light coat will prevent this from happening. If the coating drips along the edges of the grooves, remove by wiping a cotton swab or rag along the groove.

                                Many people have asked us... "What is the difference between kiln cement and Liquid Kiln Coating? Can a lid be coated with a thin mixture of kiln cement?" The answer is YES! Kiln cement thinned with water will work as a lid coating. Liquid Kiln Coating is simply a mixture of kiln cement, fine brick dust, a gumming agent, and water.

                                The great news is that lid coating lasts for several years. So, it's not something you need to worry about on a daily basis.  But, if you start getting kiln brick dust on your work, maybe it's time to re-apply.