Welcome to the wonderful world of ceramic science! This lesson covers all the
chemistry of colouring
promotional
mugs and tumblers. If you’ve ever wondered how we get the reds just right
(or why it costs more to get ceramic products in orange), this is where you’ll
discover the sizzling scientific secrets of ceramics.
If you’ve ever taken a digital stroll through our ceramic mugs page, you might
have noticed red and orange coloured mugs are priced slightly higher than their
mug brethren in more muted or darker colours. Why should coffee drinkers and tea
sippers who prefer to drink from a bright, fiery mug have to pay more? It turns
out the higher cost of red and orange ceramics comes down to chemistry. There’s
a whole complex chemical process involved in producing red and orange ceramics.
First, a History Lesson
Red and orange glazes have been popular for many years. A well-known example is
Fiesta Ware, which was produced by the Homer Laughlin Company. The red Fiesta
dinnerware, along with four other colours, was first offered for sale in 1936.
The red was extremely popular; it was also the most expensive to produce due to
the material costs and the unpredictability of the red glazes when fired in a
kiln.
One of the ingredients in the red glaze was a radioactive material called
uranium oxide. Lead was also often used in creating colours. This was a pretty
common practice before World War II until safer, economical colour-creating
chemicals were discovered. Fear not: no one is using radioactive materials in
the making of mugs these days. Science has helped manufacturers find
alternatives, and laws like Prop 65 and other federal mandates keep toxic
materials from showing up in consumer products at harmful levels.
And Now for a Science Lesson!
Mugs (and all ceramics) are usually made from clay and then forged in a fiery
kiln – an oven for hardening the dry clay. Ceramics usually go through the
firing twice, once to create a durable, hardened product and then again to be
glazed, coloured, and decorated. Using a kiln might sound like an old-fashioned
process used in a small village, but there’s actually science behind using a
kiln to create ceramics. In fact, kiln temperature can have a huge effect on
glaze colours like orange and red.
The firing process to create red and orange glazes requires more expertise and
care than the firing process to create other colours. Reds and oranges are
notoriously fickle colours in the kiln; they need to be fired in a high-oxygen
environment because carbon monoxide is produced when the carbon in the clay has
burned out. This gas can negatively affect the glaze if it isn’t replaced by
oxygen. Ceramics that are glazed with reds or oranges need to be fired at a
lower temperature, such as Cone 04, 05, or 06 (that’s anywhere from 1830 – 1940
degrees Fahrenheit). The length of time the items are fired is also important
because the reds and oranges can burn out, disappear, or change colour at higher
temperatures. This extra care can create extra work and additional cost for
these colours.
Today’s red and orange glazes (as well as many paints, chalks, and other
supplies) are cadmium-based. Cadmium creates rich yellows, reds, and oranges and
is also a stable chemical, unlike the radioactive materials used to create
colours in the past. Because of the rich vivid hues cadmium provides for
products (as well as the safety and stability it offers), it costs a little bit
more.
Orange you glad you came to class today? Creating red and orange ceramic
products takes a special chemical reaction, as well as some expertise with using
a kiln. Whether you’re looking for a bright, sunny mug to warm up the morning or
something in a cooler, darker shade, there are plenty of colours and styles to
choose from in the wide world of ceramics – and we know your logo will look
great on all of them.