There can be a fine line separating good research lab practice and voodoo compulsions. (“Loosely crimping” foil around the mouths of flasks and beakers prior to sterilization is a perfect example.)

But the core problem is one of assumptions.  Specifically, assumptions about the primary sources of contaminants in the lab.

“One of the reasons that the ‘loose foil’ habit seems somewhat futile to me, is that the practice means the user is more paranoid about what might land on their ‘sterile’ items than about whether the items ever became sterile in the first place.”—Philip Berriman, instrumentation technician, California State University (Fullerton)

Philip Berriman, instrumentation technician at California State University (Fullerton) points out that “chemists, biochemists, biologists, are naturally very concerned about the purity of their chemicals and samples.  But one of the things they don’t realize is that the number one contaminant in their experiments is their water.”

Most labs are using standard tap water.  Even in municipalities—or buildings—with excellent water treatments systems, there is a huge variance in the mineral, chemical, and biological content of what’s coming out of specific taps (even within a lab).

There are a wide range of excellent water purification systems available, designed to remove a wide range of contaminants.  But that assumes that the system has been properly installed, properly maintained, and functions as expected to begin with.  It’s best not to make any of these assumptions.