Graals were innovated by Knut Bergqvist technically and Simon Gates artistically in 1916, both of Orrefors Glassworks, Sweden. The Swedish word "graal" comes from the Latin "gradalis" meaning bowl or cup. There are many variations on this process including the use of paints and air-trap patterns. I begin each graal with a "blank" that has a layer of concentrated color on the outside. Blanks are blown on the pipe with the dimensions and design of the final piece in mind, then "annealed" - slowly cooled in a kiln. If glass is not properly annealed it will shatter. Once cool, there are a variety of possible techniques to grind away the exterior color and create a pattern. I choose to carve my blanks with diamond bits in a handheld rotary tool. Once the pattern is complete, the blank is put back in the annealer and brought slowly up to about 1100 degrees. It can then get picked up again on a pipe and be blown into its final form.
A detail of Gaia Graal blank with completed carving.
Here, the Gaia blank has just been picked up from the annealer. Grooves from the grinding process have not been melted in yet.
As the piece is heated, stretched, and blown out, the pattern is incorporated into the form. .
The graal is nearly completed. All that remains is to transfer it onto a "punty" (preheated steel rod with a small bit of glass at the tip) so that the top of the vessel can be opened and shaped.
to view the completed piece.
for another example
for a third example