SBRStL Mad Science Series - vol. 1

As is the case with my most of my strokes of genius, they are a product of the combined forces of my immediate environment and twisted imagination.  It often results in my attempt to apply an over-looked but obvious solution to a universal problem.  The project-at-hand was inspired by a burning, bathroom candle.  Subject matter: bicycle tire flats and the associated cost of tube replacement.  Most of us would agree that patching a tube for re-use is futile at best and doesn't instill a high degree of confidence when blasting down a hill on one at 45 mph.  Typically, we opt to simply replace the offending tube ($ cha-ching) and move on.  It's clean, it's simple,  but over the course of a season (lifetime) it can be expensive.  However, what if we patched the tube with it's own substance?  Not simply apply a glued-on appliqué that we pray adheres, but rather use actual molten inner-tube?  The brain is truly nature's computer.

The SBRStL R&D department is operating on an elastic race lace budget these days, but that doesn't deter us from engaging in what we consider legitimate science.  Housed temporarily in a west-county condo, our laboratory may lack many of the advanced tools and budget of larger research facilities, but not the pioneering spirit.

Needing to properly stabilize the subject, we discovered two sufficiently hefty objects (no offense to Tom Clancy) close at hand and proceeded with a project that would soon send the bicycle inner-tube cartel reeling.

The next step required securing raw materials with which to produce the liquid sealing mixture. We actually already possessed a cache of solid butyl rubber.  Also known as polyisobutylene, this synthetic elastomer was first developed in the 1940’s by German chemists.  Of particular irony was the old-school patch still evident on our sample.  The substance was then severed and prepared into strips to facilitate the conversion process from solid to liquid.

The methodology here involved raising the temperature of the butyl to just below its flashpoint by dangling it above a heat source and then applying the resultant drops of liquid rubber to the puncture area.  This straight-forward technique obviously lacked big-budget-lab glamour but after numerous attempts it lacked results as well.  The substance tended to transform immediately to a gaseous state.  However, our crack research staff, ever thinking on their feet, easily switched gears.

First, we further reduced the butyl strips into smaller bits by cross-cutting.   Once completed, a heat-conductive platform was used to the raise the temperature without exposure to a direct flame.  A brief time and numerous drug-reference jokes later, the heated rubber produced the same effect as the open-flame test.  It soon vaporized. This was proving challenging.  Once again, our staff found alternative means.

Microwaves possess wavelengths that can be measured in centimeters. The longer microwaves, those closer to a foot in length, are the waves used in ovens.  The rubber bits were next 

positioned in a container capable of safely withstanding microwave bombardment.  Unfortunately, this only resulted in our subsequent cup of Chai tea possessing a butyl bouquet.

Sometimes the solution to a problem already exists beyond the myopia of well-intentioned researchers.  The melted inner-tube concept was doomed, but here was the solution in a convenient tube applicator.  After an initial expenditure of $3.49, this was all that stood between me and the giddy excitement of freedom from ever having to purchase tubes again.  Just 2-ounces of this product could easily cover dozens of punctures with double-applications of its sealing properties.  The initial investment would be recouped after just one use.

At right is a close-up of the sealing agent as it cures over a pinch-flat area.  After it was given 24 hours to completely harden, the tube was then inflated to 110 psi without mishap.  The same process was subsequently applied to a half-dozen similarly affected tubes.

The project's ultimate success hinges on a final road test to be staged in the spring.  Taking these prototypes to the street is not without  inherent risks.  With that in mind, the R&D department made modest contingency plans.