When Life Gives You Lemons...
The past 15 to 20 years have seen an increasing use of plant materials in the cleaning industry, with citrus fueling a generous share of the growth.
The fragrant citrus fruits and their byproducts provide us with solvents (d-limonene) for cleaning and acids (citric acid) for neutralization purposes, as well as for color correction and spot removal. I first encountered "citrus solvents" about 20 years ago in the role of a hand cleaner for mechanics. The 1980s saw an increased presence of citrus solvent-built traffic lane cleaners displacing the more traditional petroleum-based products in the cleaning industry. Not only were these citrus pre-sprays effective, but they smelled good too.
As effective as it is as a solvent, d-limonene can cause problems for the cleaner if it not used properly. I recall being in the office of a major chemical formulator and having the chemist show me four bottles containing four different qualities of raw d-limonene ranging in texture from the color and viscosity of honey to water-clear and just as thin. Unfortunately, by the time a gallon gets onto the truck and into the pre-spray tank, it's sometimes hard to tell if the product is made of "honey" or "water."
A good point to start at would be to follow label directions when preparing the material for use. Dilute according to label directions using a measuring cup, not the "glug" method. After allowing ample time for soil suspension to occur, flush thoroughly to remove loosened soils and pre-spray.
Proper rinsing may be the critical factor in achieving good results when using d-limonene, either as a pre-spray or as a spotting agent (actually, thorough rinsing must be accomplished as part of any cleaning or restoration procedure). Good cleaning sense tells us that we need to remove as much foreign matter from the carpet as possible, including any materials we may have added that could be classified as "villainous residues" contributing to re-soiling problems. This thorough removal of foreign matter requires complete rinsing of the fiber using copious amounts of water.
I had been in the carpet-cleaning business for about 18 years before I encountered citric acid. During that time, acetic acid was the old standby. One of the most common problems encountered in those days was cellulosic browning. I took my first carpet-cleaning class in May 1973. It was there that I was first taught about using acetic acid for correcting cellulosic browning. It didn't take long for the introduction of "browning correction" products into the market (keep in mind that the majority of the carpet we were cleaning then was double jute backed).
Pity the poor cleaner who didn't understand the concept of "pre-spray and rinse," and who tried to clean with just the emulsifier in the tank and lots of wet passes. As the chemistry of browning correction advanced, acetic acid was supplemented or replaced by other organic acids and oxidizing agents. Incidents of browning decreased dramatically in the 1980s with the growth of Action-Bac backings. Then, in the late ‘80s, came the last major change to impact the carpet industry, the introduction of "stain-resistant" nylon.
What a concept: carpet that won't get dirty. But it did, and does, get dirty, and it has to be cleaned. It became increasingly clear that the brains that conceived this "magic" product didn't have much of an idea how the chemistry would perform in the real world. History and personal experience tells us that the material used to impart stain resistance would, in some cases, turn yellow from exposure to UV rays of the sun. And improper cleaning of the carpet would result in a similar yellowish discoloration. Back to the lab: How to correct the discoloration?
The product that works best is citric acid. Such a benign material, used in cooking, carbonated beverages and cosmetics, citric acid was deemed the ideal product for this application. And as knowledge about cleaning these stain-resistant products grew and spread, the legend of citric acid became bigger than life. There are other acids that can be, and are, used, but citric acid is firmly ensconced as the king of color correction.
The downside to citric acid? It is difficult to rinse and could be classified as a "villainous residue." Sound a little like its distant relative, "citrus solvent"? Certainly, both need the same care in use, application, and removal for the best results and to prevent potential problems. The formula for thorough soil removal remains "wash, rinse, dry," and proper attention must be paid to each step to ensure maximum cleaning and restoration. That includes complete removal of all agents used in the cleaning process, whether they are traffic lane cleaners or specialty spotters.
I hope you will take some professional nourishment from all this food for thought. Until next month, see ya!