Designing with Porcelain Tile: Get to Know the Product By Patti Fasan

Designing with Porcelain Tile:
Get to Know the Product

By Patti Fasan

Porcelain tile is one of the fastest growing categories in the ceramic tile industry, especially in North America. It has enjoyed such a meteoric rise in popularity that many consumers and designers are narrowing their choices to porcelain tile for every installation. And, although there are many varieties of porcelain tile on the market, which all have different properties, it is often wrongly assumed that all porcelain tiles are identical.

The full range of porcelain tiles is somewhat complex but a clear understanding of the different terms that identify each composition will not only simplify the selection process, it will ensure that the tile chosen is appropriate for the job. Tracking the genesis of porcelain tile production is the easiest way to identify each type and understand where, when and how it should be incorporated into the overall ceramic tile design.

Certainly, some general concepts apply to all porcelain tiles. A standard description would characterize it as having a dense impervious body, usually produced by the dust pressed method, and having extremely low porosity. Twenty-five years ago at the inception of modern porcelain tile, the industry referred to one product only as porcelain tile, since only UNGLAZED porcelain, generally with a natural surface, was in production in the early years. The original terminology required no additional defining adjectives other than salt & pepper, to describe the multi colored or granite-like look or solid describing any single color tile. The term porcelain was simple, easily understood, and the original product quickly established its value in commercial specification.

Porcelain, in that early, unglazed form, was conceived and developed to satisfy the rigors of demanding environments: exterior applications, heavy pedestrian and vehicular trafficked floors, areas subjected to excessive water penetration or temperature fluctuations, and places where damage from aggressive chemicals or acids were likely. In order to create the unique inner microstructure of porcelain, high quality raw materials and specialized production techniques are required. The pore structure is critical to achieving; good color development, mechanical strength, and stain and frost resistance. The design community particularly appreciated the extremely hard, unglazed tile's natural deep abrasion and slip resistance.

To achieve specific technical objectives, initial porcelain production suffered from a lack of aesthetics. The unglazed surface also required a higher level of maintenance and its limited surface patterning offered little soil hiding ability.

Polishing of the unglazed tile was soon adopted into the process as the resulting high gloss finish added sophisticated textures to an otherwise limited design selection. Unfortunately, surface polishing opens the closed pore structure of the porcelain body and polished porcelains are more susceptible to staining because dirt gets trapped in the opened surface pores. For this reason, particular care must be taken when using a contrasting grout color with polished porcelain tile or when selecting a light or lightly patterned tile. Sealants or other pre-surface treatments can prevent this problem as long as routine re-application of the protective treatment is maintained.

Over the past twenty years, many decorating techniques have been developed to add depth, pattern, texture and natural variation to unglazed porcelain tile. All of these treatments are incorporated into the homogeneous body, maintaining the commercial benefits of each tile while improving its visual impact and increasing soil resistance. Soluble salts, double loading and multi-pipe are just a few of the techniques now used to create natural veining effects. Dry powder applications allow granules and flakes to be imbedded into the body, and micronized powder creates intricate travertine-like patterns. Newer hammered and flamed surface textures heighten dimensional interest; more closely mimic natural stone; and enhance slip resistance. All of these decorative effects have increased the application range and added to the visual appeal of unglazed porcelain tile.

In the past five years, the compelling desire for richer patterns and additional designs led to the introduction of glazed porcelain tile. It is only with the thin layer of glaze that the industry is capable of creating the virtually limitless array of design and color familiar in other traditional ceramic tiles. While the application of aesthetic glaze effects on porcelain tile captured the interest of residential designers, it also created dramatic changes in the physical characteristics of the tile. Most notably, the glaze compromises natural slip and deep abrasion resistance of the tile and can reduce its resistance to chemicals and acids.

This new addition to the porcelain family also led to some confusion because it does not necessarily meet the performance requirements for challenging commercial applications and, there, it blurred the previously understood concept of what a porcelain tile was. In glazed porcelain, the glaze hardness or abrasion resistance now determines a tile’s suitability to specific environments and use, and some glazed porcelains should only be used in light or moderate traffic areas. Thus, glazed porcelain tile intended for floor use must be carefully evaluated based on its PEI (Porcelain Enamel Institute) test classification. In many cases, it should also be compared, on a level playing field, with other traditional ceramic-bodied tile. Consumers who insist on using porcelain tile for every application should realize that they may actually add material and installation costs to a project unnecessarily.

When selecting any of the various types of porcelain tile, it is essential to specify the correct installation materials and methods. By ISO definition, glazed and unglazed porcelain must not have more than 0.5% water absorption. This low porosity presents a challenge to bonding and requires a premium two-part acrylic/latex enhanced mortar system. To ensure the ANSI required 80%-95% adhesion (interior-exterior or shower areas, respectively) back buttering is also strongly recommended.

Knowing why porcelain was conceived and how it evolved should encourage us to question its appropriateness for every application and to understand that different types of porcelain tile will perform differently. In fact limiting our choice to any one type of tile will severally restrict other reliable solutions given the tremendous variety of quality ceramic tile products on the market. No single tile is perfect for every job-the key to selecting any type of tile for a project is to match the attributes of the tile to the desired aesthetics, performance, maintenance and budget. Remember; there is a tile for every use and a use for every tile.