You are so focus on your coffee that you never pay attention to less important thing. The stain it creates. Ohh! There are few instances. The moments it accidentally spilled on your clothes. I bet it was so annoying. It happened to me several times so I know well how it feels. There is always an option to change clothe if where you live is comfortably near or you have an extra. A cowboy style, always ready! On the other hand, the only choice is dry it patiently in front of electric fan, or, better yet, a freezing cold air con. It is ugly while still wet and ugly still after drying. It leaves a shade with prominent border. Often looks like a roughly drawn map.
Those annoying memories came back when I noticed this stained coffee filter. There must be a way to treat this filter clean.
Okay! We will not talk about cleaning. We will talk about the less important thing. The stain pattern. Notice that it always create a ring on your shirt?
Let us go back to coffee filter for a bit. In a normal drip process. Coffee grounds is place on filter then water is pass though it to extract. The filter is conical and the direction of the liquid is toward gravity. More particles pass trough the lowest point (the tip) so more stains are trapped in the end.
In white and poorly coated mug. The stain tends to get darker toward the bottom. Coffee is often drink like wine, sip by sip. The upper part, near the brim is less exposed while lower is more. More often than not, there is a bit of liquid left to dry after. That where the darkest stain shade lies.
Things get different when it spilled accidentally on table. Whatever the shape of the stain is, it always has distinct, darker shade border. Assuming the suspended particles are equally distributed and the dome shape of spilled liquid. The dome center should have the most particles. The center must also be darker when it dries out.
Coffee stain formation has interesting law of physics. The thinner part of the dome dries first. However, as it dries, the suspended particles flow toward the edge, making it darker. Thanks to livescience.com for pointing out. This coffee behavior is attributed to its rounded molecules. On the other hand, oblong and other molecule shapes holds to each other more strongly leaving a more uniform color upon drying.
Is this important? Maybe or maybe not! In any case you want to print your edible wrapper with edible ink, coffee derived pigments may not be a wise choice.
Marvin is the lead chocolate maker of Ben and Lyn Chocolate Inc. Has strong background in food research and development. Occasionally conducts training and lectures. Lecturer of Cocoa Foundation of the Philippines. Do coaching and consultancy services on his free time.