Intaglio glass blocks are the little cousins of the Sculpted Glass Module. Manufacturer Pittsburgh Corning described them in a 1960s catalog as “all-glass units in four distinct patterns featuring a recessed antiqued glass area…outlined with textured gray-colored frit fused into the surface of the glass unit itself” which could be used “to produce dimensional walls with strong textural effects…combining dramatic surface patterns with the richness and beauty of light.”
The catalog photo shows the 6 available models – 2 blank infills and four standard patterns.
And Chicago designers loved ’em. Not quite as much as the Sculptured Glass Modules, but still quite a bit.
They even came in totally clear versions, apparently. This three flat near Bryn Mawr and California is the only instance I’ve found so far.
Their distinctive appearance made them a great advertisement for the local glass block distributors; both the Hardy Glass Block Company and Imperial Glass Block used them in the design of their buildings.
Intaglio blocks could really let a designer go nuts, if he was so inclined.
Intaglios, for whatever reason, aren’t as regionally restricted as the glass module blocks; I’ve seen them in Davenport, Iowa and in Hoboken, New Jersey. And my friends Michael and Lynn located a most impressive example in Trenton, IL.