Espresso Problem Solved

Some time ago — in a post on 20-Dec-2013 — I mentioned trouble with a custom ground coffee, from a specialty coffee shop, clogging the espresso machine. I speculated that the difficulty arose from the custom ground coffee having been ground too finely. I’m pleased that the problem with using the specialty store’s coffee has been resolved, and can report my technique for using it. My speculation regarding grind size is not validated however. So, although I have a solution to the problem, how to enjoy the specialty store’s coffee, my hypothesis about grind particle size is not substantiated by what I’ve observed through the microscope.

First, the method: how to use a coffee grind that clogs the machine. The solution is like what one does with gravel to get good drainage. First put down a layer of coarse gravel — store-bought espresso ground coffee, which does not clog the machine. Then put down a layer of the finer gravel — the specialty store’s coffee. Since my espresso making usually involves coffee for two, that means two scoops, and everything works out easily: one scoop from the standard espresso, tamp it a bit, then the second scoop from the specialty espresso, and tamp a bit further, and then brew. It is excellent to be able to use this great-tasting specialty espresso in my machine.

Now, some microphotographs of the specialty coffee, and of three different standard espresso grinds. These are very crude, as I’m not a good microphotographer. Back lighting in each case. Each of the three standard espressos is a different brand of espresso from the grocery store.

The specialty coffee — the particles look a bit elongated:

And the three grocery store espresso coffees:

Each of the latter three appears to have particles which are uniform in width. So it may be that the difference is not the particle overall dimensions — related to the grinder setting — but rather to the specialty store’s grinder producing long thin particles. Those then could stick end-wise into the filter of the espresso machine.

Whatever. I’m just happy to be able to use the specialty store’s coffee, in a 50-50 mix with grocery coffee.

Best wishes,
Ken Roberts
19-Apr-2014

Brian Johnston Flower Macro-Micro Photography

One of the many excellent web resources is A Flower Garden of Macroscopic Delights, by photographer Brian Johnston. The URL for the index page is http://www.microscopy-uk.org.uk/mag/bj-flowers.html

I have had the pleasure of a detailed review of two of his articles — about white oak, and about single-seed hawthorn — in conjunction with a biology unit I am working through with a home study student. They are excellent. Johnston starts with a photo of the tree or plant, then moves in to examine various aspects of it in detail, using both macro and micro-photography. His explanations are very clear, and when Johnston notices something curious, he tells the reader.

There is a project opportunity in connection with the hawthorn sequence. Not sure if it would be graduate school or science fair — the two levels of investigation are not that far apart, after all. Spring is coming, and if you have access to hawthorn trees, you will want to examine specimens of their flowers. See Johnston’s article for details.

Wherever one looks in nature or science, there is plenty of opportunity for interesting projects. So little has been explored ! So much is beckoning !

Best wishes,
Ken Roberts
10-Mar-2014

Curly Hair and Straight Hair

Yesterday I was sitting with a young man who is interested in forensic work, and we were looking through an atlas of microphotographs — of human hair, animal hair, fabrics, and so on. Fascinating! It’s always a pleasure to look at a lot of examples of some category of object. Induction is a great way to discover relationships.

In this particular case, we realized why black people have curly hair. Among its many photos, the atlas has cross-sections of head hair samples from three racial groups. The Negroid hair sample cross-section is oval, with a length:width ratio of about 13 to 6; such hairs will curl very readily. The Caucasoid hair sample cross-section is also oval, but with a length:width ratio of 13 to 9; such hair will curl, but less readily. The Mongoloid hair sample is almost round, with a length:width ratio of 13 to 12; such hair will not have nearly as much tendency to curl. I don’t know whether the dimensions of these hair samples are typical, but the length:width ratio is at least a preliminary hypothesis for the structural basis for hair to be naturally curly or straight.

The book is “Color Atlas and Manual of Microscopy for Criminalists, Chemists, and Conservators”, by Nicholas Petraco and Thomas Kubic, CRC Press, 2004, and the hair sample microphotos are on page 220. If you have a change to browse through this or a similar book (this copy came via an academic library), I’m sure you will find it interesting.

Best wishes,
Ken Roberts
03-Mar-2014