Specification III: Appearance

The first article in this series defined performance as “the ability to withstand use and maintenance while retaining physical integrity and minimizing changes in appearance.” In the second article, I discussed the properties that influence appearance retention at the fiber level.

In this installment, I’ll cover the aspects of carpet construction and coloration that have the greatest impact on appearance retention.

Appearance Retention in Two Easy Steps

It is helpful to think of performance in terms of characteristics that, at a minimum, don’t exaggerate appearance changes and, where possible, actively contribute to appearance retention. In other words, the specifier should try to:

• Accentuate the positive — Maximize visual features that change least under traffic.

• Eliminate the negative — Minimize visual features that change most under traffic.

Minimizing Appearance Changes

Regardless how carpet looks when it is new, traffic affects its appearance in some pretty predictable ways. If you’re thinking that the carpet that would show the least change in appearance is one whose appearance has already been changed by traffic, then you’re thinking in the right direction.

Now you might be wondering, “You want me to buy carpet that already looks old? Are you insane?” No, that’s not what I’m suggesting. What I mean is that since traffic is going to cause certain inevitable appearance changes, new carpet that already shares certain visual characteristics with trafficked carpet will show the least change in appearance. Makes sense?

Think about it this way: Compared to unused areas, trafficked pile typically has:

• less tip-definition
• a flatter, less textured surface
• less luster

So which would show the greatest change in appearance: A highly-textured cut-pile style with highly lustrous fibers, or a short, dense, untextured style with finer yarns, less tip definition and delustered fibers? The answer is the latter, because its characteristics differ less from those of trafficked pile.

Continuing with that premise, here are the most important factors to consider to minimize traffic-induced appearance changes:

Pile type — Loop pile carpet outperforms cut pile carpet of similar density and fiber type. Loop-pile constructions also eliminate the problem of twist loss. Additionally, performance characteristics like shading and pile reversal are greatly reduced — virtually eliminated, in fact — in loop-pile styles.

Pile weight — I’m listing pile weight here primarily to call out the fact that its importance is greatly exaggerated in relation to appearance retention. Remember that “total pile yarn weight” is just that — all of the pile yarn in the carpet. In many commercial products, as much as half (and sometimes more) of the yarn is buried in the carpet’s back, where it contributes nothing to the carpet’s performance. Some residential styles like shag might have an awful lot of yarn, but the density is so low that it performs terribly. What’s more interesting than weight is density, described below.

Yarn type — All other things being equal, carpet carpet of continuous-filament (BCF) yarns tends to retain its appearance better than carpet with staple pile yarns. Appearance problems like fuzzing are greatly reduced or completely eliminated with BCF yarns.

Yarn Size — In cut-pile constructions, smaller yarns tend to retain their twist considerably better that larger yarns. Large three– and four–ply yarns, once used in popular residential “cable” styles, are especially susceptible to twist loss. The largest yarns virtually explode under foot traffic and it’s fair to say that those styles are only suitable as decorative floor coverings in untrafficked areas.

Pile fiber — In my previous post in this series, I made light of the “ideal fiber” question by answering without explanation that solution-dyed nylon had the best balance of the Big Six performance properties a carpet fiber needs.

It is true that the suitability of a fiber for a particular application depends upon how well its characteristics match the use conditions, and since use conditions vary from job to job — and even within large installations — it is reasonable to conclude that no single fiber is perfect for all applications. However, nylon has the best balance of properties for the vast majority of uses, so much so that the cases where it is not the best choice are the exceptions rather than the rule.

Solution-dyed nylon is rare in residential styles (the range of colors is too limited), its availability in the contract arena arguably makes it the ideal fiber for commercial applications where the budget allows.

Pile thickness — Pile thickness should balance the desired aesthetics with the performance needed for the application. Generally, the shorter the pile, the better the performance.

Pile density — Density is the mass per volume unit of the carpet’s pile. Generally, the higher the density, the better the carpet performs. However, in cut–pile styles, excessively high density may result in concentration of the effects of traffic on the tips of the tufts, resulting in accelerated flaring and flattening. This rarely is a concern in residential styles, but is sometimes observed in extremely dense commercial styles, particularly with fibers of higher luster.

Tuft (or loop) density — The number of tufts or loops per area, usually expressed in tufts or loops per square inch. Higher tuft density decreases the definition of individual ends; the less tip definition the pile has to begin with, the less definition there is to lose under traffic.

Twist (applies only to cut-pile styles) — Generally, the tighter the twist the better, unless the twist is to the point of imparting texture, in which case it may be more of a detriment than a benefit.

Disguising Appearance Changes

While the characteristics above can be controlled to minimize appearance changes, this second group of characteristics are those that actively disguise the effects of traffic. They do this by confusing the eye — giving it a lot more visual information to process so that the traffic-related changes are only a small part of the carpet’s overall appearance.

Pile texture — Texture can either help or hurt appearance retention, depending on how the texture is created. Textures that depend upon features that will be changed fairly quickly by traffic exaggerate texture change. As a general rule, the less texture there is to begin with, the less there is too lose, and the less texture change will occur between trafficked and untrafficked areas. On the other hand, texture helps disguise the normal shading characteristics of cut-pile styles as well as helping to hide footprints and lines from vacuuming.

Shade — Colors that are too dark tend to show texture change and abrasion more quickly than lighter colors; however, colors that are too light have poor soil hiding characteristics and require a higher level of maintenance. The optimum midrange colors provide a proper balance between being dark enough to minimize soil visibility but not so dark that they emphasize texture changes and shading.

Color — The closer to the color of dirt, the better. Browns, including taupe, darker tans and the like are closest to the color of most soil.

Pattern and Coloration — Generally, the more boldly and busily patterned a carpet is, the better it will disguise changes in appearance, provided that the pattern itself is not dependent on factors that are quickly altered by traffic, like texture. (Patterns created by texture variations may “walk out” quickly under heavy use.) More durable patterns of construction and/or color are better for long-term appearance retention.

Patterns of pre-dyed yarn generally remain more sharp and vibrant than printed patterns. Yarns with heathered (multiple shades of a single color) and tweed (multiple colors) colorations help break up the uniformity of solid-colored styles and are very effective at enhancing appearance–retention. Graphic and random (e.g., floral) patterns are even more effective at hiding changes in appearance.

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