• What is Texture?

Getting The Right Feel … The Riddle Of Texture

By Michael Kaplan

Imagine eating a peach that tastes like a peach and is peach-pink, but is shiny and hard. Imagine an apple that has all an apple’s refreshing flavor, yet is soft and fuzzy. Biting into either would be a surprising experience – and maybe not a pleasant one. Texture matters; which is why people still willingly pay more for leather rather than vinyl car seats and wood floors rather than linoleum.

Designers know, however, that modern materials are almost infinitely adaptable. Sophisticated coatings and surface treatments can give versatile, lightweight, inexpensive plastics and composites the same textures we associate with nature’s work. Whether you want chrome, cowhide, granite or walnut, there is a process available to provide the satisfying feel of these natural materials without their high financial (and often environmental) cost.

Creative textures:

The problem for designers is specification: establishing standards for texture that are understood and maintained all the way through the development and manufacturing process, from initial inspiration to mass production. When dealing with color, we have RGB ratios or Pantone numbers; sound can be summarized by frequency and amplitude; even flavor has only five parameters, while fragrance has a well-established common language based on natural ingredients. Texture, however, is different, yet essential. Think of, say, the clinging, slightly damp, elastic yet silky feel of the inner skin of an onion: how would you describe that to a process engineer?

This is the problem that interests Dr. Hengfeng Zuo, Research Fellow in Product Design at Southampton Solent University in the United Kingdom. “There is an increasingly wide range of materials available,” he says, “but little understanding of how users perceive and respond to them, either physiologically through their senses or psychologically and culturally. We know these responses are strong, but we haven’t yet given them dimensions.”

In its simplest form, texture is the shape of an object at various scales, from macroscopic – where we can say a surface is bumpy or rough or smooth – to microscopic, which provides attributes like “glassy” or “matte”. Even at this simple level, though, Dr. Zuo points out that we have to go beyond geometrical dimensions to define texture in the way we actually perceive it: “the physico-chemical qualities are equally basic – qualities like moisture retention, thermal conduction, temperature, or hardness. Our experience of texture includes all these aspects.”

Etched micro-textures:

Ni-Cu alloy

bronze

Al-Cu alloy

Al-Si alloy

cast iron

This is an essential point in Dr. Zuo’s work: the subjective feeling of texture is inseparable from its objective reality. Recent brain-imaging studies have revealed that we imagine sensations using the same neural pathways with which we actually sense; we anticipate all those physico-chemical qualities when we see a texture – which is what makes a soft apple or hard peach so unsettling.

To help designers develop a consistent vocabulary to describe texture, Dr. Zuo and his colleagues have defined four dimensions that cover both its objective and subjective qualities: the geometrical, the physico-chemical, the emotional and the associative. Within each dimension they have identified paired opposites: words that suggest extremes of a particular quality and therefore create a range between those extremes. “For the geometrical dimension, for example,” explains Dr. Zuo, “you could use descriptive opposites like plain – bumpy, regular – irregular, repetitive – non-repetitive, and line-scattered – dot-scattered. It’s not a complete list, but it shows the type of words that have only a geometrical significance.”

Simulated "virtual" textures:

silk

rain drops

foil

concrete

pearl

Words for the physico-chemical dimension cover the objective tactile qualities that go beyond geometry:  warm – cold, hard – soft, moist – dry, sticky – non-sticky. These are all distinctions that people can recognize in texture and, more importantly, identify consistently in tests when presented with contrasting materials.

The emotional dimension describes subjective impressions. You might think that this is entering the indefinable realms of individual taste, but Dr. Zuo disagrees: “pairs like comfortable – uncomfortable, lively – dull, elegant – ugly, modern – traditional still show consistent responses over many test subjects, although they often need visual as well as tactile contact with the object.”

The associative dimension draws on the vocabulary we all use when trying to describe a new texture: “what’s it like?” Feathery, honeycomb-like, oily, silky – even intangible associations like Zen – provide a reference to other subjective experiences that will help define the texture in a way everyone can understand.

Associative descriptions:

feather-like

honeycomb-like

oily

silky

buddhist

This four-dimensional descriptive lexicon is an important achievement. It brings texture studies up to the level of fragrance studies: a discipline with consistent words for objective and subjective qualities. But what Dr. Zuo and his colleagues now want to discover is the relationship between the objective and the subjective: exactly what physical properties create which perceptions? This can be a complex business: in acoustics, for instance, the perception of loudness is not necessarily correlated with the intensity of sound. As any stimulus becomes stronger, we tend to pay less attention to it. We can also create perception, for example seeing color when, in reality, there is only a moving pattern of black and white. Psychophysics remains a difficult subject.

So where does this leave the designer? “Designers create textures based on many inspirations,” says Dr. Zuo. “In some situations, the inspiration is nature, whether in direct imitation of a natural texture or in the subjective perception of nature – so you can have a wave-like pattern without necessarily having a wet or a sandy surface.” Nature-inspired patterns, he says, add a special quality in that they seem less “designed” and more harmonious.

Natural textures:

water drops

desert

leaf

zebra

wood

Now, though, consumers have such wide-ranging experiences, both real and virtual, that designers can expect emotional and associative responses to textures not found in nature: computer-generated textures, microscopic textures, technological and scientific textures and the free, fantasy textures of abstract art.

Designers can isolate the associations of particular textures just as they specify color families for emotional impact. Understanding how people are likely to respond to particular textures/surface finishes both at a visible and subconscious level will help designers to specify products with particular material texture to maximize positive user experience. The key, though, is to define each texture using a consistent, shared vocabulary. Some day we may have the equivalent of a Pantone number for the feel of a peach – but until then, Dr. Zuo and his colleagues can help. Further information will be available at the website www.material-sense.com, to be launched end-July 2007.

New technology textures:

photo-etching

silicon elastomer

in-mold coating

in-mold decoration

3D pattern finish

This article is based with kind permission on the work of Dr Hengfeng Zuo and Mark Jones of the Faculty of Technology, Southampton Solent University, UK, in their paper “Exploration into formal aesthetics in design: (material) texture”.