In the world of fiber optics, there only are two truly critical precision cleaning operations.The first is “prep” before fusion splice.The other is “end-face cleaning.” Both are essential to deployment of reliable, high-capacity networks.But as new and advanced as modern fiber networks might be, most technicians still are cleaning them with the same fluid used in the 1960s: isopropyl alcohol, also called IPA.
    So here’s the headline: to get the most from your investment in advanced fiber equipment, companies must update their cleaning processes and stop using IPA.Over the last 20 years, the precision cleaning industry has developed high performance products that cost less, are safer to use and perform better than traditional alcohol cleaners. Let’s take a look:
Why Clean?
    The basic answer is as simple as a stain on your shirt.In fiber optics, this is not merely acosmetic issue. Stains and debris on an optical surface will degrade the transmission of the signal. “Clean” directly equates to more reliable transmissions and mechanically stronger splices.Optical fibermust be pristine to transmit reliably and to splice properly.
    The existing standard for end-face cleaning is confusing. IEC 61300-3-35 clearly states that IPA is no longer acceptable for end-face cleaning. But IPA commonly is packaged and promoted for fusion splice prep. Far too often splicers and end-face cleaners forget to send each other “the memo:” do not use this chemical for every fiber cleaning application!
    Throughout the 1990’s numerous new solvent choices evolved to replace ozone-depleting chemicals, and some of those experiments migrated into the fiber optic industry. Some companies used alcohol in different mixtures. Precision hydrocarbons were tried and “tweaked” to minimize environmental issues. New chemicals such as hydrofluoroethers (HFE) and hydrofluorocarbons (HFC) entered the market.I even have seen companies using unconventional cleaning fluids, such as dish-washing detergent and SimpleGreen®. It was a crazy time.
    Most of the exotic (and ineffective) practices died outdue to economic, environmental, performance or worker safety concerns. Today the list has been abbreviated to just a few, proven choices. Amazingly, more as a nod to ‘tradition’ than ‘effectiveness’IPA remains on the list.There is another reason: IPA is inexpensive and often purchased from a drug store.
    I recall training an important fiber optic distributorand I gently suggested to the owner that IPA was not “best choice” for cleaning fiber. Coolly, he advised me that he and his Mom had started their massive international business transferring IPA from 55 gallon drums into small bottles.Their highly successful enterprise exists to this day and “we’re not going to change.”
    But one has to ask, Why not?Why have perceptions of IPA remained unchanged while everything else in the industry has evolved at a furious rate?
What Don’t We Understand?
    Isopropyl alcohol has many names. On safety data sheets it may be called isopropanol, rubbing alcohol, propan-2-ol, 2-propanol, dimethyl carbinol or just IPA. It is an organic compound with the chemical formula C3H7OH. No matter what the name, on the safety data sheet it will carry the official “CAS number” of 67-63-0. It is a colorless, flammable compound with a strong odor. It has a wide variety of medical, industrial and household uses but it has many flaws, as well.
    For a start, IPA is neither a very effective nor very versatile cleaner. IPA’s cleaning ability is limited to human body oil and ionic salts but not much more. IPA is not effective on mineral oils and most hand lotions. IPA does not clean oils and greases very well. Since fiber optics has now expanded into mining, oil fields, as well as telecom networks and data centers… selecting ‘the right stuff’ becomes an essential ‘best practice.’
    Drying-speed is another issue with IPA. Slow-drying IPA can be trapped inside a fiber optic connector. This once-pure liquidmay leach out inconveniently and contaminate an end-face. A familiar characteristic of any liquid is its boiling point; the lower the boiling point the faster a liquid will evaporate. Water boils at 100˚C and dries slowly; alcohol boils at 78˚C so it dries slowly as well. Many companies have introduced new cleaning choices that boil near room temperature. These cleaners will‘flash-dry” and will not leave contamination or moisture trapped on the fiber.
    IPA has another unexpected characteristic: it is hygroscopic which means it attracts moisture to itself.Studies of 99.9% IPA reveal that a bottle of IPA in an open container will lose 7% of its strength in as little as 15 minutes. IPA continues to absorb moisture until it reaches equilibrium at about 65%. This is why the “rubbing alcohol” purchased at a local store is about 30% water. The manner in whichthe cleaner is packaged is critical to its performance.
    Water doesn’t just dilute IPA’s already feeble cleaning power. It also will add residues carried in the air. Those contaminants fromthe air — and others from those cheap plastic bottles — will be left behind when the IPA dries. This is the source of the “haze” that IPA leaves after cleaning. The haze may interfere with transmission of light (increased insertion loss) and also may affect the transmission of one wave length verses another wave length, which can be very troubling in DWDM systems.
    No matter how pure the IPA may be when purchased, it will become contaminated when it is poured into a pump bottle, dispenser or an uncovered container. Guaranteed. Each time a drop of IPA is squeezed out of a traditional pump-bottle, air enters. This is reality… not just sometime, not just maybe… but each time it is dispensed. IPA out; water and contamination in. For optimalresults, the packaging should be hermetically sealed.
    There is another concern: the “headroom” in the drum or pail of IPA will have air that contains moisture. This exposure continues hygroscopic deterioration. There is no practical way a technician can estimate the purity of IPA that has been opened or improperly stored. The best practice is not to use IPA at all.
    Can companies buy pure IPA and solve the haze problem? Many try, but I believe that the purchase of 99.9% “reagent grade IPA” is a waste of money and effort. Here’sthe‘little secret’ about reagent-grade IPA: since it is the most pure it is the most hygroscopic. 99.9% “reagent-grade IPA” will reduce itself to “drug-store” purity long before the container is emptied. Unless the techs are buying reagent-grade IPA in a hermetically-sealed container and using it under very controlled conditions (such as protecting it with a nitrogen blanket to control moisture absorption) your company is just wasting money.
    Storage and packaging is a problem that is rarely discussed but is crucial in this environment. IPA is a hazardous liquid because it is flammable. All flammables should receive special storage and handling. These characteristics also make it difficult and expensive to ship IPA, and IPA certainly cannot be carried on to airplanes because of numerous TSA, DOT, FAA and IATA (International Air Transport Association) regulations. As a result, it often is difficult for techs in remote locations to have the proper cleaning fluid on hand. A better choice would be to select a nonflammable, non-aerosol, nonhazardous liquid which are easy to ship anywhere.
    Environmentally, IPA is a Volatile Organic Compound (“VOC”).This means it contributes to local smog.Now, tiny bottles of IPA aren’t going to do much damage. But many locales — such as California and New Jersey — have implemented clean air legislationthat make it very difficult to legally use VOCs in such containers. Emerging nationssuch as China also have considered the VOC problem to become a better global neighbor. So while a technician may be able to get IPA it may not be legal to use it.Single-use penalties can be as high as five figures and include incarceration! Yes, we live in a new legislative environment… and one of “best practice” performance!
    For fusion splice prep there is one last concern: the residual moisture in the IPA will corrode the electrodes on expensive fusion splicing equipment. As the high-intensity arc fuses the fibers the heat not only evaporates remaining IPA but also the moisture embedded in the IPA. Yes, you can replace the electrodes, but would it not be better-practice to select a chemical that does not hasten their demise? This is the reason many major fusion splice producers have gravitated away from IPA for splice preppingand now market application-specific products in unique packages.
What Is the Answer?
    The point is simple: there have been many important advances in the science of cleaning over the past three decades. The essential reality is IPA has been surpassed and replaced by safer and more effective chemicals.
    Fiber optics need fast, consistent and reliable contamination removal,as well as a drysurface.The selection of a fluid for cleaningfiber optics is a complex trade-off of many attributes: cost, storage, handling, purity, actual cleaning ability, drying time and worker safety to name a few. Modern, nonflammable fluids—along withthe appropriate non-cellulose wipers(no paper cosmetic-like nose-tissues!) — are the best choiceto ensure a clean surface that is optimized forultra-high speed and ultra-capacity fiber optics.The best choices are ultra-pure, fast-evaporating, nonflammable cleaners in non-refillable, hermetically-sealed containers. When choosing a wiper, I prefer hydroentangled non-woven polyester/cellulose cloth, not cheap paper wipes. These are readily available. Just ask!
    Look for better products: they are on the same catalogue page as IPA! Remember, by the time that expensive “reagent grade” IPAis used it will have lost almost all its cleaning ability, wasting time and money...compromising the performance of your network.
About the Author
    Ed Forrest has a long career in the fiber optic industry, including patents, products in production and patents pending. He is an expert on the 3-D nature of connectors, contamination, cleaning and the implications for network design and performance. Contact Ed at edforrest@fiberopticprecisoncleaning.com