Glazing | White Layer | Black Layer | Industrial Process | Assessment

Glazing

To accomplish the manufacturing of this prototype we began with unglazed (bisque) mugs. This allowed us to get a basic mug design that we really liked, rather than a less-designed, more standard mug. We glazed the mugs with a brush-on satin black glaze and had them fired.

Bisque Mug	Glazed Mug

White Layer

We then began testing a variety of inks and application methods. After the Concept Refinement review we had decided on an epoxy based color changing ink for the color changing portion of the product. The epoxy ink changes from colored (in our case black) to translucent. Since we wanted the image on the mug to be white, we then had to find a suitable white ink for the base image.

For the white base image, we initially chose a non toxic enamel paint for both it's non-toxicity and it's durability. We also tried a an epoxy screen printing ink similar to the heat-sensitive ink. Despite trying a number of methods to apply the white layer, including airbrushing, pad printing, rolling, traditional screen printing and a mask/screen application method, we were unable to achieve a satisfactory surface finish. Therefore, we decided to use a white acrylic spray paint for the prototype, despite its being ultimately unsuitable because of durability concerns.
White Spray Painted Layer

Black Layer

For the black epoxy ink top layer, we found the best method to be a mask layer of Frisket, a low tack masking film, underneath a tightly clamped screen printing screen. The Frisket serves as the stencil while the screen meters the ink. Applying the black epoxy ink by rolling, using a Frisket mask, worked as well.

Weeding the Frisket	Clamping on the screen
Applying the Ink	Wiping the Ink

The epoxy ink we used is designed is designed to either air cure for 5-7 days or for 10 minutes at high temperature. We did find the curing process to require high precision (over-curing resulted in a slight yellowing in the translucent (hot) state.

Industrial Processes

Ultimately we found that making these mugs by hand would require significantly more control in the prototyping process. Industry, however, has machines that do it perfectly. There are two main methods industry uses to apply ink to mugs: sublimation and screen printing. Each technology has certain attractive features, but also drawbacks. The sublimation printing process begins by covering the mug with a special coating. When heat is applied, the sublimation ink is transferred from a non absorptive paper that is clamped to the mug. The primary benefit of this method is that there is no raised ink on the mug surface. The screen printing process allows a much wider range of ink options, but limits the number of colors in the design. For printing on the cylindrical surface, the mugs are rotated while simultaneously being translated underneath a flat screen.

Assessment

There are some challenges and clear next steps in the development of these mugs into a real product, most especially working with a manufacturer on design details and industrial printing methods and tradeoffs. Our initial request for a quote indicates that for a run of 100 mugs, the unit price would be approximately $12.00. We believe that for runs in the thousands, the cost would drop significantly making the final product available to the consumer at an attractive and competitive price within the $15 to $20 range.