To get a clear notion of what some viruses actually look like, I downloaded verbal descriptions from the Internet, adapted drawings from a medical textbook and consulted electron microscope photographs. Oddly, virus shapes are more often geometric than biomorphic. She mixes sodium carbonate and sodium bicarbonate with the silica and adds colorants so the final work is chartreuse instead of the natural pale pink-beige. Mostly, it's been press molded to make beads or statuettes. As Egyptian Paste dries, salts leach from within to the surface by evaporation, covering the surface with crystals that create the glaze during firing.
Crystal growth disrupts the surface, obscuring the artist's touch and distancing the maker.
The salt crystals leach unpredictably to the surface, which means that each jar is uniquely patterned and toned, often with curiously shaped islands of salt-grain white. Whitehead used wax molds to make the virus shapes. Herpesviridae, for example, is a cutaway, whose outer sphere looks like a rubber ball with cloves stuck in it. The models vary widely in size. Whitehead placed some directly on the lids, but others were too long for this, so she had to fold them over.