Why does coffee creamer sometimes create a film over coffee?

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When I put my (powder) creamer in my coffee and stir it for the first time, it’ll dissolve. I always make sure I stir it A LOT. After a minute or so, there will be a white film over the top of my coffee, and it’s just creamer. I can try stirring it more after that appears, but all it does is break up the film and make it float around. It stays there until I’m at the very last of my mug, and there’s no point in trying to drink it because it just tastes like you’re drinking liquid creamer straight out of the bottle.

In: Chemistry

Coffee with creamer is not a solution (in which case all the parts of the fluid are mixed evenly and are very hard to separate, like with salt water or soda) but rather a suspension (in which the parts are not perfectly mixed, and can be physically separated out more easily, like straining the fat out of milk).

Powdered creamer is fairly light, so when it randomly happens to hit the upper surface it tends to stay there, which means that a film quickly develops on the top of your cup. Also, it has a rough texture which tends to create tiny little pockets that can hold air bubbles, which both make those particular particles lighter and less soluble.

Depends what’s in the creamer. They’re often just “corn syrup solids” (basically sugar) and “vegetable oil solids” (basically powdered oil) with some emulsifiers – it could simply be that the emulsifiers aren’t holding on tightly enough to all of the oil solids, resulting in some of the oil separating out and forming a permanent slick on top of the coffee. It could also be that you’re not making the coffee hot enough to fully integrate the creamer.