The 1910 issue is known for being a very “clean” issue. There are not known design errors in the more than 40,000,000 stamps that were printed. Fortunately, errors like folded paper are known to happen in this issue.
But there were errors in the printing process -and not many-. Some imperforated stamps are known, but the highlights are the folded paper errors when the stamps were being printed.
Here we have an example of the 10 Cts. What happened is that the paper was folded when printing the stamps and when the paper was unfolded, a part of the stamp didn’t have ink on it.