"What do you want, brick?" -- Louis Kahn
A discussion of materials and integrity usually begins with how a material is used. We first try to understand the nature of a material, and then we deploy the material in such a way that it harmonizes with its nature, or possibly subvert or extend these properties in a knowing way.
But I would like to think for a moment about why certain materials feel more "right" than others. This is quite a questionable assumption that you might not share. One might just as easily start with a presumption that all materials have equal weight and are equally likely or possible to use. But my belief is that most of us don't think this, that we think that certain materials are "better" than others.
Stone. Wood. Brick. Concrete. Glass. Steel.
These are the building blocks of architecture. There are many other materials -- ceramic, tile, terra cotta, plastic, fabrics of all kinds, and so, so much more -- but architects keep coming back to these. Why?
It is possible, even probable, that the primary reason is some combination of economics, availability, and suitability. In other words, we use these materials primarily because they work best.
Yet I am going to propose three other reasons for why we might prefer certain materials. The first is phenomenological and perhaps fairly intuitive, the other two less so.
The Qualities of the Material Itself. I cannot discount the possibility that certain materials are pleasing in and of themselves. It is of course hard, if not impossible, to categorically state that one material is more pleasing than another, as this is an apples to oranges comparison. But perhaps there is another way to think about it.
In our day and age we have gotten pretty good at making materials that mimic other materials, or even "improves" them by increasing their durability, longevity, or strength. However, when we compare these materials to the original, we almost always prefer the original.
It could be simply a matter of integrity, stemming from the knowledge that the copy is not the original, but I think it also has to do with the fact that we mostly mimic only two properties, color and texture. The copy does not have the cellular structure of the material. The cellular structure provides other visual qualities (the opacity of the material, the depth and resonance of the color) and other haptic qualities (grain, grittiness, moisture content) that are equally important. Further, we never even attempt to capture the smell of the original material, or its thermal properties, or its sound absorption/reflection properties. So matters of integrity aside, the mimicking material is different in a very real and perceptible way.
This segue into the discussion of mimicry points perhaps to why certain materials don't seem as good as other materials. Perhaps they don't have as rich a range of properties, or properties that we desire as much. If a material like plastic doesn't engender the same emotion as other materials, perhaps it is lacking something in the depth of its color, or in its haptic qualities, to make us desire it less in spite of its many other favorable qualities.
Or maybe it is something else that makes us desire certain materials less.
The Amount of Processing. Some materials you see in nature and you can imagine using them straight away. I can pick up a stone and stack it, I can fell a tree trunk and post it. These are simple, elemental gestures, and I think these materials resonate deeply because the distance between their natural state and their used state is so short.
Other materials are each just a little less elemental. The adobe brick is pretty straight forward -- mold something from wet earth, dry it out. With a brick, we accelerate and intensify the drying process with firing. Concrete is trickier -- a calcifying or hardening agent, in ancient times quicklime, needed to be found and added to aggregates in the right proportion. Steel is trickier yet -- a metal, iron, needed to be found and carbon added to it in the right proportion, all done under tremendous heat.
One can find examples that show that each of these materials was less accepted, at least initially, than the one before it. Perhaps this was because each one required additional steps to produce. The stone was found raw, or hacked from the earth. The tree needed to be felled and stripped of branches. The brick needed to be molded, and fired. To this day, brick and wood structures are not as prized as those made of stone. Similarly concrete was originally only used for engineering projects in Rome, or at least masked with stone when used in other structures.
In our day, new materials are even harder to trace to their natural state. Many plastics, for instance, come from a viscous material, petroleum, and needs to be substantially processed. There is even a hierarchy to certain materials such as wood. The "ancient" wood is really rough hewn timber. Dimensioned lumber such as the 2x4 is a later invention, processed and standardized in a mill. Plywood is wood improved into a sheet less likely to warp or split, but with slicing and sandwiching and gluing to make. With each step, one is further and further from the original raw material, and so the material itself is less intuitively understood.
The Ancientness of the Material. Similarly, the sociological age of a material and its use matters. I think some materials may be more suspect simply because we have not lived with them long enough. Concrete was almost certainly feared initially, it was not until it was reinforced with steel many centuries later that its use really took off. We needed to live with it, improve it, try it out. Same with steel. We originally built with cast iron, but it was too brittle and melted too quickly in a fire.
With each new material, we need time to get used to it, to ensure it works, to use it best. Until then, there is some doubt. The oldest materials represent stability, a quality obviously prized in architecture.
I think these are some reasons we might feel certain materials are more "right" -- the richness of their properties, the distance from their original state or the number of steps to process them, and how long we have been using them. But I don't know why this should inherently be so, and I question it. Why should we prefer things that are natural to ones that we had a hand in making? Why do we not find joy in a new technological innovation as a celebration of a god-like ability to create? Are we skeptical of ourselves or our creations? Is all this just prejudice stemming from a conservative viewpoint, a product of how we view things at this moment in time, while another age might see materials differently?