Sunday 28 April 2013

Be Sharp!



Ah, notes. We are taught to keep notes in grade school, starting with a pencil so we can correct mistakes. Later, we make notes in ink so we cannot correct mistakes. Not that we should ignore errors, just that we should not try to hide them. Lab notes should be recorded as experiments happen, not from hazy memories. Many labs demand ink notes kept in hardback notebooks, signed and dated every day by the experimenter, signed and dated by the supervisor. This used to be critical for patent purposes, when discovery dates were legally established with such documents. A major adjustment to the computer world was maintaining proof of the discovery chain in a legally acceptable way, as note keeping entered the digital realm.

But there is another dimension to this. Objects in labs need to be labelled so we can keep track of them, and this is where we really get into trouble. Every scientific neophyte learns to pay attention to the labels on the shafts of felt tip pens. 'Water soluble' is definitely something to avoid (who buys these pens for labs?), as is 'temporary' or the euphemistic 'semipermanent'. No matter how carefully you craft your handwriting on Petri dishes or flasks with such pens, you will find mirror images of the lettering in green ink on your fingers, and unintelligible smears on glass. Even if you succeed in labelling your test tubes, two or three weeks later the ink will have faded away to a ghost.

So, permanent pens are a must. They still leave ink on your fingers, which takes a lot of soap and rubbing to remove. They leak in your pockets. Most white lab coats have black, red and blue splotches of permanent ink, the trophies of productivity and absent mindedness. Next, you learn to check the actual tip of the pen before writing too much. Sometimes the felt nib is frayed or flattened as if it has been hammered against the bench top in a stippling frenzy. If you write large enough for the letters to be legible with those pens, almost the whole surface of a test tube will be covered with ink. Then there is the problem of writing on cold surfaces misted with condensation after removal from the freezer. You can buy very expensive pens to do that.

Once the reliability of a lab pen has been established by experimentation, strong feelings of ownership arise. People will label their personal pens with other 'permanent' markers, in a usually futile attempt to keep them from wandering. Others will hide their special pens in drawers, or place them in pen holders with conspicuous 'DO NOT REMOVE!!!!' signs. As the senior lab member, I usually don't respect these claims of ownership, feeling that my grant money has bought it all and everything is actually mine. But don't take my pen!

Permanent inks may not be washable with water, but many can be removed with ethanol. It helps to know this in advance. I once had a student who wiped a bunch of tubes with ethanol to sterilize them before opening, only to find that he had erased all the labelling telling him what was in the tubes. This was an aspect of the famous Patchwork Mouse episode in the mid 1970s, when a clever grad student enhanced mouse skin symptoms with a felt tip pen, only to have the diagnostic symptoms washed off with ethanol by suspicious technicians.

What solvents won't erase, time will. Because I procrastinate a lot and don't like to throw things away, I am often trying to read lab labels that are several years old. My own handwriting is bad enough even when fresh. Other people's handwriting is worse. You find these old things with the faintest outline of a permanent label visible. Dissecting microscopes can help. You tilt the surface at different angles to catch the right angle of light, and take the finest tipped permanent marker you can find, and try to reconstruct the writing. Sometimes it works, sometimes the result makes sense, but often you can't make any sense of it at all.

More and more, we use printed labels, graduating from thermally printed plastic labels to two dimensional barcodes with adhesives guaranteed to survive a nuclear holocaust and lettering guaranteed to remain legible even if sent crashing into the surface of the sun. Or at least until the database necessary to interpret them crashes, becomes obsolete, or the universe comes to an end.

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