We had our results, but John deserved that chance to redeem himself. Again, he braved the Kool-Aid powder and prepared to drink from another glass of water.

This time, when the sour powder kicked his saliva glands into full speed, he spit out his mouthful of red.

With a lot less liquid in his mouth, it was easier to cut off the saliva out-flow.

This glass was a vast improvement, but the red coloring had make its mark. Some backwash was still evident.

The backwash experiments were complete. 

We had expected to discover that certain containers were more susceptible to backwash than others. There was some evidence supporting that, with the aluminum can and drinking straw coming to light as the worst offenders.

More significant, it turns out, is the attention and skill of the drinker. If the courteous drinker is actively working to limit his or her backwash, spit transfer can be held to an absolute minimum. 

As for the drunks and the babies, well, you might as well just kiss them and get it over with.