Sealing wax? - maybe he didn't like the result so he just glued the pages together?
In some parts, Beethoven pays little heed to spacing out the notes in a measure, extending the five-line staves with wobbly lines in his own hand. High notes soar above the staff. The handwriting grows agitated to match the music. His clefs are ill formed. In one place, he pastes an entire half-page over a botched section with red sealing wax."
And other fancy stuff.