All right, it is that time of year when all things are HOT! If you have seen the heat map of the US in the last week, red is everywhere! So let's get some basic principles down and see how we can apply them to the materials in your dental lab.
First, hot air rises. Everyone remembers that one from the first time we understood Hot Air Balloons. If you have forgotten, and live in a two story home and your kids reside upstairs, they will remind you. If you have a basement, you have undoubtedly retreated there to watch TV and recognize that it is at least 15°F cooler than the next floor up. Once again, Kids on the top floor will remind you.
Next, cooler air sinks.
I learned this early in life as my grandparents lived in a modest single floor house. However when my dad was about 12 or 13, he and Grandpa dug a basement under the house. It was a two-bedroom house and in the summer, the grandparents would move down to the bed in the basement where it was definitely cooler than upstairs. No air-conditioner…just physics.
We now live in a world where air conditioning is nearly everywhere. In general, it is capable of bringing the inside air to about 20-30°F lower than the outside. Most of your thermostats (same as a thermocouple in your burnout, porcelain or sintering furnace) are set to 72° or so (some are at 68° ...you energy grabbers!). Is that a variance from the general operating temperature of your lab? What was it in the winter…78°F? What about the temperature of the water coming from your tap? Is it colder or hotter in the winter versus the summer? Even if you do heat the space in the winter, if you reduce the temperature at night and return it to normal in the morning to save energy, it will take longer for the solids in the lab, like furniture, benches, gypsum, investment, porcelain furnaces, to return to the air temperature you walk into in the morning. Physics.
Now let's talk Chemistry. Generally, if you add a cold material to a cold material, it will take longer to complete its reaction than a warm material to a warm material. If you add a cold material (like water) to a warm material, like stone, the two materials will try to equalize temperatures. Will it speed up the chemistry? The answer is …sort of. However, nothing like combining two warm materials. Which heats up faster a liquid or a solid? Well actually, it is not a fast rule but generally the liquids we work with heat up faster than the solids we work with. The solids have more mass or density so it takes more energy to heat them…or cool them.
What is your air conditioner doing to the physics and chemistry in your lab? Especially right under the vent? Are you mixing investments there? Are the bowls stored there? Is the plaster bin or the investment drawer there?
At Whip Mix Corporation, we conduct all of our tests in a stable environment. Room temperature, humidity, machines, even the same people. So we can, with confidence, publish performance numbers for our materials. However if you are not doing the same things that we are doing in protecting the chemistry and the physics, you cannot expect the same results.
Recently a customer of ours was having an issue with the setting speed of an investment and was quite upset with us, because they were nowhere near our published number. In the end, we discovered that they were using a home mixer (baking type) which rotates faster than a standard dental mixing machine. More friction energy into the mix…faster set time. Physics and Chemistry.
Changing the parameters of the physics or the chemistry changes your result, just like changing the parameters of your pressing or fired ceramics changes the result.
You should expect to see seasonal changes and heat or cold variant changes. If you are having trouble adjusting for these changes then call us, or e-mail us in technical support and we will help walk you through the tests to get back on track. We do this every day and the only ‘dumb question’ is the one you already know the answer to. Let us help.