beardedbruce -

The LOC PAE site lists 5 titles for him: Hortiz search results.

There's also one at Duke: When I Walked Home From School With You.

Glen Emery "credits his songwriting and music abilities to his grandfather, Joseph Hortiz, who made his living in the minstrels in the early 1900's".

References at genealogybank.com suggest he did appear in blackface - the heading is Minstrels at Penn Joe Hortiz and Company of Black-Face Artists Features. Unfortunately, without a subscription, you can only see the headings (some 400+ from newspapers though) and a small piece of the article scan.

Mick