What is “a stick of blue Keel”?

What is “a stick of blue Keel”?

Help!

January 3, 1910, my grandfather, Will Hobby, wrote Cousin Mabel about a New Year’s Party with a “hard times” theme:

“You should have been here to see our hard-times ball New Years Eve—I made a suit out of two gunny sacks——then I had a black and a white shoe with sox to not match—my collar was studded with nails—to keep them from throwing me out—The one pocket in the trousers was large enough to hold …deck of cards, dice, forty or fifty Panamanian nickels, a large stick of blue Keel and other junk. The keel was fine for marking [dance] programs except that I couldn’t read anything written with it and sometimes had to hunt for a number that matched mine—”

Does anyone have any idea what a stick of Keel could be?  Does capital K indicate a brand name? Is the work mis-spelled?  A hundred years ago, would you and I have known what he was talking about?

By the way, the image below is NOT blue keel, since I can’t find a picture of something I can’t describe.  Can you guess what this is?

Been Here? Done That? Tell Me About It!