How Does Aspirin Find a Headache? (20 page)

Will
Super Glue Stick to Teflon?

We were wary of contacting Loctite and Teflon about this almost metaphysical Imponderable, for it would be like prying a confession from the immovable object (Teflon) and the unstoppable force (Super Glue) that one of their reputations was seriously exaggerated. But we are worldly wise in such matters. After all, we had already cracked the centuries-old conundrum about “If nothing sticks to Teflon, how do they get Teflon to stick to the pan?” in
Why Do Clocks Run Clockwise?
We were ready for a new challenge.

So first we contacted Du Pont, the chemical giant that markets Teflon, a registered trademark for polytetrafluoroethylene (which, for obvious reasons, we’ll call ptfe). As we expected, Kenneth Leavell, research supervisor for Du Pont’s Teflon/Silverstone division, took a hard line. He firmly holds the conviction that Super Glue won’t stick to Teflon, at least “not very well and certainly not reliably.” Here are some of the reasons why not:

And then he lays down the gauntlet:

So, the immovable object claims near invincibility. How would the unstoppable force react? We contacted Loctite’s Richard Palin, technical service adviser. And he folded like a newly cleaned shirt. Yes, Palin admitted, Teflon lacks the cracks necessary for Super Glue to enter in order to bond properly; there would be nowhere for the glue to get into the pan. Yes, he confessed, the critical surface tension is too low for the adhesive to wet the surface. Yes, he broke down in sobs, Super Glue would probably just bead up if applied to a Teflon pan.

Just kidding, actually. Palin didn’t seem upset at all about Super Glue’s inability to stick to Teflon. By all accounts, there doesn’t seem to be much demand for the task.

Why
Do Many Women’s Fingernails Turn Yellow After Repeated Use of Nail Polish?

Chances are, the culprit is one of two types of ingredients contained in all nail polish:

But don’t assume that yellow nails are necessarily caused by the chemicals in nail-care products (or other, noncosmetic chemicals, such as inks, shoe polishes, and dyes, which can also stain nails yellow). Many heavy smokers, for example, have yellow nails. Even the ingredients in some orally administered pharmaceuticals can stain nails.

Physicians often examine fingernails to help determine the general health of patients, for many illnesses are betrayed by yellowing. The most common noncosmetics cause of yellowed nails is a yeast or other type of fungus infection underneath the nail plate. But many other, more serious illnesses can occasionally be diagnosed when a physician spots yellow nails, including diseases of the lymphatic system, thyroid, chronic respiratory disease, diabetes, and certain liver and kidney diseases.

Other maladies are tipped off by different-colored nails. If the normal Caucasian nail looks pink, because of the ample blood supply to the nail bed underneath the nail plate, it can turn white when a person is anemic, and blue if the patient is suffering from heart or lung disease and insufficient oxygen is sent to the nail bed.

Now that we’ve scared you sufficiently, we’ll remind you that nail polish is much more likely to cause the discoloration than the illnesses we’ve chronicled above.

Why
Are Most Corrugated Boxes from Japan Yellow?

Unless it is bleached, the color of a box will be the color of its main material source—the wood that is turned into pulp fiber. In Japan (and China), the most plentiful source of fiber is straw, which has a yellow color, whereas North America’s main source for pulp is tannish trees.

Robert H. Gray, vice-president of the corrugated division of Old Dominion Box Company, told
Imponderables
that demand for paper is so great that most countries turn to local fiber sources that can be “easily grown and harvested in volume.” Corrugated boxes often contain recycled fibers besides wood, and Japanese boxes tend to have a higher percentage of recycled material in their pulp, both for ecological reasons and because straw fibers are weaker than wood fibers and bond less effectively.

As a result, the natural shade of Japanese boxes is more variable than our reliably colored kraft tan boxes. We don’t know whether the yellowish tinge of straw is what motivated Japanese boxmakers to dye their boxes yellow, but that is indeed what they do, as James F. Nolan, vice-president of the Fibre Box Association, explains:

Not that American boxes are beyond dye jobs. Although tan boxes are not dyed, liner-board white boxes are, according to Jim Boldt, of corrugated container giant Great Northern.

One glimpse of what undyed paper might look like was supplied by Karl Torjussen, of Westvaco. He asked us if we could think of the color of the cardboard backing on legal pads. “Sure,” we responded, “sort of a dishwater gray.”

That gray is the
natural
, undyed color of newsprint that has
not
been de-inked. No one cares too much what the back of a legal pad looks like, but we might find a stack of gray boxes utterly depressing—which is why, if boxes are made out of mostly recycled material, we dye them white and Asians dye them yellow.

Why
Are Covered Bridges Covered?

We have driven by stretches of rivers where, it seemed, about every third bridge we passed was a covered bridge. Why is one covered when the next two are topless?

The most obvious advantage to a covered bridge is that it blocks “the elements,” particularly snow. Accumulated snow can render a bridge impassable, and it is true that covered bridges are found most often in cold climates. Of course, one could argue that engineers should design covers for all roadways. But as we learned in
Do Penguins Have Knees?
(ah, but have we retained it?), bridges remain frozen long after adjacent road surfaces, primarily because bridge surfaces are exposed to the elements from all sides, the bottom as well as the top.

But then some folks believe that covered wooden bridges were originally constructed to ease the fears of horses, who were skittish about crossing bridges, particularly if they saw torrents of water gushing below. The fact that covered bridges resembled wooden barns supposedly also allayed the horses’ anxiety.

This question is reminiscent of one of our chestnut-Imponderables: Why do ranchers hang boots upside-down on fenceposts? The most likely answer is the same for both: to save wood from rotting. Alternate cycles of rain and sun play havoc on the wood. According to Stanley Gordon, of the Federal Highway Administration’s Bridge Division, an uncovered wooden bridge might last twenty years, while a covered bridge can last a century or longer.

How
Do Waiters and Waitresses Get Their Tip Money When the Gratuity Is Placed on a Credit Card?

Let’s look at the life cycle of a credit card transaction at a restaurant:

This is the point at which many diners have no idea what to do. For some reason, the myth persists that waiters do not want you to charge their gratuity. Walter Sanders, director of corporate affairs for Citicorp Diners Club (Citicorp bought Diners Club in 1980), phrased the dilemma so charmingly that we are allowing him a blatant plug: