Vallien's studio glass was now developing more towards a metaphorical world with themes such as liberty and captivity, warmth and coldness. A new method of glassblowing in sand gave him the freedom to control the artistic process.

Bertil built up a large network of contacts in Sweden and the US through his many exhibitions. By now he had acquired an international reputation and was invited to participate in various workshops at the American glass studios. In the early 70s, he came into contact with a new technique. At the Kent State University in Ohio, glass artist Henry Harlem demonstrated how to blow glass bowls and bottles in a sand mould. This technique allowed a closer contact with the working process at the furnace. Bertil took up this method and adapted it to the requirements of the Åfors factory. The mid 70s saw the production of a number of a-symmetrical bowls and bottles in underlay technique with iridescent surfaces produced by various oxides. Every object being quite unique due to the inconsistency of the sand-moulds.

He continued with the sandblasting technique but discontinued the whorl and scroll motifs from the 60s. The decorative gave way to a new kind of imagery - waterfalls and reindeer, flying men and lightning flashes. In contrast to the sparkling extroversion of the sandblasted objects from the 80s, the style was now enigmatic and introspective. Gunnar Lindqvist, Bertil's biographer, sees the introduction of imagery as a further move away from the functional (aspect): "...where the rich imagery takes precedence over material function - or rather one should say: the unchanged function of the vessel as receptacle unites with symbolic imagery which may be at variance with the contents of the vessel. The bowl begins to carry a visual expression of its own."

In the sandblasted bowls from the latter part of the 70s imagery and form are perfectly wedded. Looking at them one perceives them not as patterned bowls but as a hybrid of painted canvas and sculpture. The effect is stunning. With a few symbols he has freed the otherwise so alluring glass surface. The upper sandblasted area is in strong contrast to the lower darkened base. It is a complex world that presents itself. The figures are solitary, transfixed and mute, the environment cold and melancholy. We cannot tell if this is the realm of death or the nightmare world of some forgotten culture. The public saw these bowls for the first time in 1975 at an NK exhibition in Stockholm. A critic from Form magazine found an element of hopefulness in that these enigmatic themes provoked reflection and suggestion.

The same questing approach characterises Vallien's sand-cast sculptures through the 70s. But there is no clear-cut theme, as in the ships from the 80s. The piece known as 'Untitled' from 1971, is a free moulded sculpture. With its unyielding weight, and absence of visible imprint, this sculpture defies interpretation. A closer look, however, reveals a number of small figures that resemble rock carvings.
The massive "Indian" from 1973 is more lucid (distinctive) and is his first effort at a sculpted head. The following year he produced "Celestial Journey's End" which links up with the mystical theme of wagons from the 60s. It is an evocative creation that silently asks questions of us: is this the anticipated goal? Is it the end of the journey? What is death? What is life?

At the end of the 70s Vallien began using simple forms for sand-casting. By attaching two cubes to a glass sphere with angled coloured rods he sought to make use of a variety of contrasting shapes. He was to cultivate/refine the thematic use of shape throughout the next decade.

The 70s may be seen as a long maturing process for Vallien's artistry. It is now that he discovers his world of metaphor and the first seeds of the thematic formal world which he would later so masterly refine during the 1980s. His sandblasted bowls from the 70s are among his very best work. The sand-cast sculptures are,with few exceptions,more sketchy, lacking the focus and cogency that characterises his later work. However, this sketchiness is interesting as we follow his explorations??, but it is not until he has thoroughly worked out a theme based on a firm intellectual footing that BV is at his best.
Clarity and mysteriousness are the two opposing words that summarize Vallien's artistry.

Untitled, 1971. Photo: Ola Terje.

Kultplats, sand - casted sculpture from 1972.
Photo: Ola Terje.

Indian, sand - casted sculpture, 1973. Photo: Ola Terje.

Celestial Journey´s End, 1974. Photo: Ola Terje.




Sand - blasted bowl from 1976. Photo: Ola Terje.





Sand - blown vase, 1976. Photo: Sten Robért.