The 7 Most Common Misconceptions about Carpet Cleaning Chemistry – Part 7 – Wool Carpet

Misconception #7 – Wool carpet is delicate and requires extreme caution to clean

This misconception has always boggled my mind. Maybe it is because my grandmother had a 40 year old wool carpet installed in her living room that we played on every Christmas as children. All of her grandchildren (and there were plenty of us) did everything imaginable to this carpet and it still looked good. Wool carpet is NOT wimpy.

So why are there special formulations for cleaning wool, special directions, stand-alone registry’s and certification programs and more? Well the first thing we have to do here is differentiate between wool fibers in rugs, and wool wall to wall carpet. We are going to be talking about wool wall to wall installed carpet. We will leave the discussion of wool rugs to another misconception series. The second thing we need to do is get a little historical perspective. At one time, most tufted wool carpets used jute backing. Jute is simply raw, less processed cellulosic material. Wool is very absorbent. It holds onto water better than a synthetic (plastic) carpet, so if you overwet it, it takes longer to dry. Well actually, even if you don’t overwet it and you apply airmovers, it still takes slightly longer to dry than a comparable synthetic carpet. Back then, extraction systems were mostly portable. If the carpet was extremely soiled, multiple wet passes were usually required to get the appearance improvement necessary to please the customer. Combine an overwet carpet, poor drying conditions, and jute backing and you were asking for trouble. The carpets would often develop cellulosic browning (from the jute backing, not the wool. Sheep are not a plant). Sometimes, the jute backing would actually shrink (again, the backing not the wool).

Side note: Wool does not likely shrink. Don’t believe me? Soak your wool sweater in a sink full or water. Get it soaking wet. Now throw it in the dryer on the hottest heat setting. Then pull it out. The wool shrank, right? Your XL sweater is now a small. Nope. The wool did not shrink. The weave of the fabric shrunk. You can stretch the sweater back to the old XL size. The wool is all still there. Unfortunately it won’t look very good. It will look stretched out and ruined, but nothing bad actually happened to the wool fiber itself, only the weave. Weigh it before and after your little experiment. It will weigh the same. The wool is all still there. If wool really shrunk when it got wet, why don’t the sheep get smaller after it rains?

So the problem in those carpets was never the wool. It was the jute backing. Most tufted wool carpet today in the United States uses polypropylene backing, hence the fear of and danger of browning or shrinking is greatly reduced or virtually eliminated. (If you are reading this and you clean carpets in Australia, the United Kingdom, or virtually the rest of the world, most of your tufted wool carpets still use jute backing, so be forewarned).

We also know that tufted wool carpet is often the carpet of choice in large Las Vegas casinos. It wears great and does not conduct electricity – important with all of those electronic gambling machines. Some of the higher end casinos in Las Vegas clean some of their wool carpet daily…with hot water extraction. Wool is NOT wimpy.

So what do we know about cleaning procedures, chemistry and cleaning tufted wool carpet. Let’s look at some of the “rules” you may have heard.

1. Wool should not be cleaned with carpet cleaning formulations that contain optical brighteners. Not a worry. Optical brighteners have not been used by reputable formulators in carpet cleaning solutions since the late 1980’s. The only reason you need to worry about this is if you are buying an el cheapo chemical from the big box store, the home improvement center, or the local jan-san house.
2. Wool can be damaged by prolonged exposure to oxidizing bleaches. So can Nylon. How long is prolonged and how strong does the oxidizer have to be? The large majority of carpet cleaning solutions do not contain oxidizing agents (presprays, extraction detergents, acid neutralizing rinses) so that is not a huge concern. No reputable chemical formulator adds strong oxidizing bleach like chlorine bleach to any carpet cleaning solution because of the effect it could have on nylon carpets also. Cleaning or stain removal products that contain hydrogen peroxide are usually identified as that. Does a peroxide based stain removing mixture allowed to dwell on the wool carpet for a few minutes actually damage the wool fiber itself? What is worse – the unsightly stain or the slight effect on the fiber?
3. Wool smells really bad when exposed to reducing bleaches. True, it does unless you like wet dog/decaying egg smell. But once it is cleaned out, did it damage the wool fiber itself?
4. Both reducing agents and oxidizing agents in a carpet cleaning solution can cause bleaching or alteration of carpet colors. Same as the discussion above for damage to the fiber. The large majority of carpet cleaning solutions do not contain oxidizing or reducing agents (presprays, extraction detergents, acid neutralizing rinses) so that is not a huge concern. Cleaning or stain removal products that contain hydrogen peroxide or a reducing agent are usually identified as that. Does a peroxide based stain removing mixture or a reducing agent based stain removing mixture allowed to dwell on the wool carpet for a few minutes usually cause color loss, reduction or bleaching of colors? The same can be said for residential nylon carpet. When using a reducing or oxidizing stain removal mixture, there is always a potential for some color loss. What is worse – the unsightly stain or the slight risk of color loss on the fiber?
5. Wool should not be cleaned with a total alkalinity that is too alkaline. This is again true for nylon, especially residential stain resistant nylon carpet.
6. Wool exposed to high alkalinity over an extended period of time or repeated applications can damage the skin (epidermis) of the wool fiber. It can result in “felting.” The Las Vegas casino wool carpets do not appear to be disintegrating right before our eyes. How long? How many times?
7. Wool should not be cleaned with temperatures greater than 160 degrees Fahrenheit. Are they talking about the temperature of the water striking the carpet or the temperature of the wool fiber itself? Testing by DuPont in the late 1980’s proved it is practically impossible to raise the temperature of the fiber itself above 150 degrees Fahrenheit, even with a fire breathing dragon of a truckmount. What happens bad if you clean a tufted wool carpet with your truckmount set at 200-220 degrees Fahrenheit? No one has answered that question with any demonstrated measurements that I am aware of.
8. The carpet cleaning solution should not alter or affect the flammability rating of the carpet. One of the best things about wool carpet is that it is naturally flame resistant, without the addition of any kind of flame retardant. Water based carpet cleaning solutions are not going to make a wool carpet more flammable. They are not going to remove the flame retardant because there was not any applied. The only thing that could potentially alter the flammability of a wool carpet would be the use of a solvent cleaning solution that was non-volatile (it did not evaporate after use). Your favorite presprays, extraction detergents, and neutralizing rinses do not contain any kind of solution which could cause this issue.
9. The carpet cleaning solution should not contain any agents which lead to rapid re-soiling of the carpet after cleaning because they leave behind some sticky or soil attracting residue. The same holds true for all synthetic carpets too. Sticky residues left in any carpet can cause rapid re-soiling.

The purpose of our discussion here today is not to disparage any organization or agency which provides cleaning advice or information on how to safely and effectively clean wool carpeting. Certainly there is value in having a product independently tested for its cleaning effectiveness and its propensity to contribute to rapid re-soiling. The problem is how the testing protocol is implemented. Does “lab soil” emulate properly the characteristics of real soil? Why does one testing organization not accept the findings of another testing organization?  If you review the cleaning rules above, most apply to nylon and wool carpeting. In a small industry like the professional carpet cleaning industry who ultimately pays for all of this testing? The carpet cleaner that purchases the tested product that is who.Wool is a fabulous carpet fiber. It is soft. It wears well. It is naturally flame resistant. It is sustainable and renewable. It cleans up effectively when properly maintained on a periodic basis. It is NOT wimpy, or delicate, or hard to clean. A trained and thoughtful cleaning professional always practices reasonable caution when cleaning any carpet. Don’t be afraid of wool carpet! Embrace it as the high end carpet that it is. Clean it with confidence.

For residential wool carpet that is being properly maintained on a periodic basis, use  WoolMaster Rug and Fabric Cleaner as your prespray and Clearwater Rinse as your neutralizing detergent. If it has not been cleaned in more than two years, use  FastBreak HD as your prespray, and HydraClean as your carpet extraction detergent. For commercial wool carpet, use FastBreak HD as your prespray, and HydraClean as your carpet extraction detergent. It is always a good idea to use airmovers to assist in rapid drying of any wool carpet.