In our house, we have a black ceramic cooktop on which we often place items (that are not dishwasher safe) to dry. One day, I noticed an interesting color display associated with the plastic tube of a turkey baster. This effect is shown in Fig. 1.

It looks very much like a birefringence pattern or perhaps a thin-film interference pattern. So, which is it? After a bit of thought, it was easy to rule out thin-film interference: the tube is too thick and has no thin-film coating. In addition, the colors are only visible in the reflected image on the stovetop. So, this must be birefringence pattern, not unlike that discussed in previous articles in TPT.1,2 Birefringence usually requires that we observe an object between two crossed polarizers, as shown in Fig. 2.

However, Leung and Sagehorn noted a similar effect when observing light reflected by...

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