Can civilisation survive flip-top tartar sauce?

Probably.  But the processes of engineering ethics analysis can be applied to small things as well as big ones, as the following story shows.

I happen to like tartar sauce on fish, an inclination I share with many other residents of English-heritage countries, according to Wikipedia.  In France, where it was invented, it’s called sauce tartare, but even Wikipedia doesn’t say what it has to do with Tartars, an umbrella term for peoples of north and central Asian region called Tartary.

Whatever.  In the US, tartar sauce is basically mayonnaise with some chopped sweet pickles and other stuff mixed in with it.  The mixture is rather thick, and for easy dispensing, in the last decade or so it typically comes in a plastic flip-top squeeze bottle. 

If you think about it, a flip-top squeeze bottle is a considerable feat of engineering.  It has to be flat enough so it doesn’t kink if you squeeze it, like a round cross-section would.  And the clever little hinge on the side of the flip-top toggles to let you either close it or open it at a fixed angle. Some of the most anonymous engineers of our anonymous profession have to be food-packaging engineers. 

When the bottle is full, the stuff comes right out when you squeeze it.  But as it empties, even if you store it top down (which the maker intends you to do), the sauce is so thick that a lot of it sticks to the sides.  Last Friday we had fish, and I noticed the tartar sauce was low.  Thereupon I strayed into a region of use that was, all things considered, probably not recommended by the manufacturer.

My wife, who is famous for getting the last three ounces of anything out of a bottle, would have unscrewed the cap and gone after the last little dabs with a knife or something.  But, physicist that I like to think myself as being, I decided to apply a little physics to the situation:  centrifugal force.

Of course, there is no such thing as centrifugal force, although it’s colloquially called that.  It’s really just inertia applied to a circular motion.  The point is, if you force a container to traverse a circular path, the acceleration of the curved path will produce a force on the contents that appears to be directed radially outward, although it’s really just the mass inside continually trying to go in a straight line, and you’re continually keeping it from doing so. 

So I picked up the squeeze bottle from the kitchen table where we were sitting and prepared to give it the old centrifuge treatment.  I’d used this many times before with ketchup squeeze bottles, and it had proved to be both safe and effective.  But there are some subtleties involved, such as not squeezing the bottle so hard when you swing it that the top pops open.

I’m still not sure exactly what happened.  It had been a long day, I was tired, and maybe I wasn’t paying the attention I should have brought to the situation.  In any event, I gave one mighty swing on the tartar-sauce bottle. 

Judging by the aftereffects, the top popped open just at the beginning of the swing, because the stuff radiated over a 210-degree arc that extended from the stainless-steel front of the refrigerator behind me, across the floor where evenly spaced streaks recorded the fact that a stream of rapidly extruded tartar sauce separates into shorter globs, across a few books lying on an unused chair, up the gray kitchen-window curtains, and as a subsequent investigation by my wife revealed, some even made it to a few spots on the ceiling. 

Supper was suspended as we got out the paper towels and spray cleaner to remedy the worst damage.  The curtains, which needed washing anyway, turned out to be washable in an ordinary washer, and the books suffered no permanent damage.  I think I got most of the spots off the ceiling, and the stainless-steel refrigerator (which is anything but, actually, and you have to use a special cleaner to get it looking only streaky instead of like a bunch of third-graders with sticky hands have been at it) looks about as good as it ever does.  

So as engineering disasters go, this was definitely on the mild side.  Still, I wish it hadn’t happened.

As with many such incidents, the root cause can be laid to human error.  At least two precautions are needed before one attempts to centrifuge a squeeze bottle.  The first is not to squeeze so hard on the thing that the top pops open.  I’m sure there are various pressure ratings for different tops, and maybe I was used to using the more robust ketchup-bottle tops, which would take quite a squeeze to open.  But the tartar sauce top is smaller, the little plastic catches that keep it closed aren’t as strong, and I suppose some mechanical engineering senior design project could investigate the question of what pressure blows the top of different squeeze bottles, but it’s probably a waste of time.

I could have also held my fingers over the top when I was swinging the bottle.  And if I’d been more alert I might have thought to do that.  But I didn’t.  Sins of omission can get you in trouble in engineering just as much as sins of commission. 

In the Big Freeze we had here in Texas in mid-February, the power to a water plant that supplies about half of Austin’s water failed.  The engineers who designed the plant some five decades ago knew that this might happen, so they installed auxiliary generators and a “gear switch” (a term the Austin American-Statesman used) to change the power over from the external utility to the auxiliary on-site generators.  But when the workers at the plant went to switch over the power to the emergency generators, nobody on site knew how to operate the switch.  As water usage soared due to people running faucets and water main breaks, the water supply dwindled and caused multiple-day outages to many thousands of people in Austin.

One hopes that the managers of Austin’s water system are planning to institute better training of their operators.  And one (at least my wife) hopes I won’t try to get the last tartar sauce out of the jar the same way I did last Friday.  We have all learned lessons, but that will help only as long as we remember them and use them the next time. 

PS: I thank my wife for putting up with a husband who now and then does things like centrifuging tartar-sauce bottles.

Karl D. Stephan

Karl D. Stephan received the B. S. in Engineering from the California Institute of Technology in 1976. Following a year of graduate study at Cornell, he received the Master of Engineering degree in 1977...