>>Given that everyone who has responded has used something different, and
>>it all seems to work, I'm gonna use chewing gum. Beemans or Cloves, I
>>haven't decided.

Hi List and Rocket J Squirrel,
Fibergum is an asphalt caulking reinforced with fibers of cellulose (they used asbestos fibers before they were banned).  "Fibergum" was the brand name used by Domtar when they were still in the roofing business.  There are lots of similar products used by roofers to seal asphalt shingles and metal flashings.  Most lumber yards or roofing supply businesses sell this product in tubes for caulking guns or in pails.  Other names include asphalt plastic cement, roof patch, and Black Jack (there are many other names).  These products make great water barriers but do not last long if they are exposed to direct sun light.  I used Black Jack when I replaced my sky light a few years ago and it is still water tight.
George,
'85 Westfalia