A (Very Long) Primer on Record Cleaning Fluids Upon urging by some members, I have collected, revised and expanded my recent SH threads on record cleaning fluid (RCF). The information is re-cast here as a primer to provide a basic understanding of how RCFs work. Such chemical information is sadly missing from most discussions on RCF which too often leave us mystified or, far worse, badly misinformed. The alcohol scare is a good example of a resilient myth that is particularly misleading because it contains an element of truth. It is not my intention, however, to vilify or endorse any particular RCF. I only hope that a better understanding of RCF chemistry will enable you to select the best product available and to use it effectively and safely on your own. Finally, a few words about myself. While I make no claim to be an expert on RCF or Vinyl, the discussion below is based on my years of experience working in Surface Chemistry R & D and caring for my own LPs. Note: If you loathe long technical discussions, feel free to proceed directly to the summary at the end. The Vinyl LPs, also known as Vinyls, are made from an eponymous polymer (lower-case vinyl) also known as PVC (polyvinyl chloride). Like many thermoplastic materials, vinyl requires many additives during its manufacturing to give it the desired physical properties. These additives represent only a small portion of the overall formulation. Common additives include stabilizers (metals such as barium, calcium, cadmium, lead, zinc, etc.), colorants (dyes) and plasticizers (softeners). Plasticizers are softening agents that give vinyl its low-temperature flexibility. They are of particular interest in record cleaning because, unlike stabilizers and dyes which are chemically bound to the polymer, plasticizers are simply mixed within the polymer matrix. The most common plasticizers are phthalate esters (derived from naphtha, a polyaromatic fraction of crude oil). Phthalates used in vinyl are large, polar molecules which have no significant vapor pressure (minimal loss by evaporation). They are, however, soluble in alcohol or surfactant solution (!). A loss of plasticizer renders vinyl brittle and susceptible to further mechanical damage. The Contaminants Even a pristine Vinyl still sealed in its jacket is covered with a thin layer of mold release, a lubricant used to ease the removal of the record from its mold after stamping. The chemical composition of this mold release varies but it is traditionally a lubricant of medium molecular weight. Modern mold releases are polytetrafluoroethylene (PTFE or Teflon) in liquid or dry form. Used Vinyls have a host of other contaminants which are less well defined. The most common contaminant is dust, on the Vinyl surface or imbedded in the Vinyl grooves. Dust can be of two origins: skin-cell debris and fine particles of dirt and sand. Other contaminants are finger prints (skin oil), adhesive (label glue), cigarette smoke and materials of unknown and sometimes surprising origins. Ideal Properties for Record-Cleaning Fluids An ideal record cleaning fluid (RCF) must possess the following properties: 1. An RCF must be able to “wet” the Vinyl surface. Wetting ensures intimate contact between RFC and Vinyl without which cleaning is impossible. In Surface Chemistry parlance, the fluid must have a low or zero contact angle on vinyl. In layman terms, the fluid must “spread” on the vinyl surface rather than bead up. Most polar organic solvents such as alcohol and chlorofluoro alkane tend to wet vinyl. Water does not unless it contains a polar organic solvent or a surfactant—familiar surfactants are soap and detergent. 2. An RCF must “penetrate” tight spaces within the Vinyl groove. If an RCF cannot reach the contaminants in those nooks and crannies, it cannot remove them. (Remember how dirt ground into a fabric is far more difficult to launder than surface dirt?) To squeeze through these micron-size spaces within the Vinyl grooves, an RFC must have a low surface tension. The smaller the pore size, the lower the surface tension required. (Think of surface tension as an indicator of how easily a liquid droplet can be deformed and squeezed through tight spaces). Water containing a sufficiently high concentration of an effective surfactant has a low surface tension and can access all areas. Alcohol, pure or diluted in water, has a moderate surface tension and cannot access the smallest pores. Pure water has a high surface tension and is kept out of all tight spaces in the grooves. 3. An RCF must be able to “dissolve” contaminants on contact. Polar solvents like alcohols can; water cannot unless it contains alcohol or surfactant. With alcohol/water mixtures, the amount of dissolved contaminants varies with the type and amount of alcohol that helps disperse them throughout the water. A surfactant removes organic contaminants differently. At concentrations above the cmc (critical micellar concentration), surfactant molecules spontaneously aggregate into small spheres called micelles. Each micelle consists of a few to a few hundred surfactant molecules. Their polar heads are aligned outward to form the spherical surface of the micelle and allow it to be soluble in water; their hydrocarbon tails point inward to form the organic core that acts like a reservoir to “solubilize” a large amount of contaminants. The cmc of a typical surfactant in water ranges roughly from 0.01% to 0.25% by weight. Note: Diluting a commercial RCF below its cmc will yield poor cleaning due to high tension, poor solubilization and low foam. Consult the manufacturer for safe dilution. Below the cmc, a surfactant becomes merely a wetting agent. 4. An RCF must be able to “transport” contaminants away from the vinyl surface. Dissolved organic contaminants are transported within the bulk of the liquid itself (by dispersion or solubilization). Dust and other solid contaminants are carried away mostly by froth or foam (a processed called flotation). RCFs that are the best foamers are also the best dust removers. They are, in decreasing order of foamability: surfactant in water (best), alcohol in water and pure water (worst). 5. An RCF must not leave any “solid residue or thin film” behind after vacuuming. It is obvious that RCFs should contain as little solid residue as possible. But beyond that, all liquid components of the RCF should also be easily removed by vacuuming. While the bulk of RCF is vacuumed off the Vinyl surface, a small part of it is usually left behind as an “adsorption” film. How well this very thin film is removed by vacuum depends on it volatility. The Overlooked Role of Adsorption Film Adsorption complicates matters in the removal of RCF from the Vinyl surface. Whenever a liquid (RCF) comes into contact with a solid surface (Vinyl), a fraction of the liquid’s component, be it alcohol, water or surfactant, will “adsorb” onto specific sites on the solid surface via electrostatic attraction and/or hydrogen bonding. So, after the bulk of the liquid has been removed by vacuum, a small fraction of the water, alcohol, surfactant and other RCF additives remains on the vinyl surface as an adsorbed film consisting of several layers of molecules. If the adsorbed material is a highly volatile alcohol then it will quickly evaporate under vacuum before it has time to “leach” any significant amount of plasticizer. Adsorbed water does no harm to the Vinyl or the sound even if it remains on the Vinyl surface for a long time. On the other hand, adsorbed surfactant (with water) left for some time on the Vinyl surface can leach plasticizer. Some adsorbed surfactants can also lead to static noises when dry (same as static on laundered clothes in the dryer). Recommendation: Regardless of RCF used, rinse the freshly cleaned Vinyl surface with distilled water to re-dissolve adsorbed materials and then re-vacuum the Vinyl surface to remove as much residual materials as possible. Specific Record-Cleaning Ingredients and Contaminants It should be clear by now that no single fluid has all the properties of an ideal RCF. Commercial RCFs usually combine different ingredients to maximize cleaning and minimize damage. There are three typical mixtures. 1) Combine several alcohols with water to form a broad-spectrum fluid, which is capable of dissolving a broad range of contaminants. 2) Use surfactant(s) in water to provide deep cleaning (by solubilization and flotation). It should be pointed out here that the ability of a surfactant to solubilize a specific contaminant depends on the molecular weight and molecular structure of the surfactant itself. To tackle a broad range of contaminants, it is often necessary to blend several surfactants. 3) Combines surfactant(s) and alcohol(s) in water to clean a broader range of contaminants than either a surfactant or alcohol alone can. Other components may also be added (lubricant, preservative, static suppressor) but they do not attend to the cleaning process. I will spend the remainder of this primer discussing a few specific contaminants, typical components of RCFs and their potential harm if improperly used. Removing Mold Release As previously stated, modern mold releases for Vinyl are polytetrafluoro-ethylene (PTFE or Teflon), usually in liquid form. The presence of fluorine makes this a tough contaminant to remove. Even pure alcohols have limited effect on mold releases. Organic solvents of the chlorofluorocarbon type (CFC similar to Freon but larger) work best on PTFE: they can quickly dissolve the mold release but not the plasticizer because of large differences in molecular structure and volatility. CFCs such as trichlorotrifluoro ethane were used to remove mold release until they were banned because of their adverse effects on the air and the ozone layer. I am ambivalent about the need to remove mold release. On one hand, any organic material on Vinyl, even an exceedingly thin film, must be considered a contaminant and should be removed. On the other hand, mold releases are PTFE molecules, which are among the softest polymer extant, especially in comparison to vinyl. I seriously doubt that a thin film of such material would much effect on Vinyl sound—I am in the realm of educated guess here. Presently, environmental considerations rule out the use of CFCs, although it’s unclear whether larger and less volatile CFCs are as harmful as Freon. Leaching Plasticizers: How Bad Is Alcohol? This is easily the most confusing and misunderstood topic about RCF. First let’s get one thing straight: old Shellac records are incredibly sensitive to all alcohols and none should be used on these precious old records, period. Vinyl is not at all sensitive to alcohols but the plasticizer within the vinyl matrix is. Alcohols can slowly dissolve a plasticizer out of the vinyl thus rendering it brittle in the long run. This dissolution is, however, a slow process—the alcohol must first “wet” the vinyl surface, “enter” the grooves and finally “diffuse” into the vinyl matrix to dissolve the plasticizer. Each step of this process depends a great deal on the polarity of the alcohol and its concentration. When an alcohol is diluted with a lot of water, it quickly loses its ability (polarity) to dissolve plasticizer. A mixture of 5 to 15% IPA in water has a limited ability if any to leach plasticizer especially when the contact time is restricted to a few minutes or less. There are many legitimate reasons for using alcohol (or alcohol mixtures) as an additive in an RCF. 1) Alcohol leaves no film behind and thus has no sonic signature—this is a very desirable quality to some audiophiles. 2) Though inferior to surfactant, alcohol is still a good cleaner and will work adequately with new or moderately dirty records. It cannot remove deeply imbedded dirt or very sticky materials but it can handle a broader range of contaminants than a surfactant. 3) As long as the concentration of alcohol is low and the applied liquid quickly removed from the Vinyl surface with a powerful vacuum, an alcohol/water cleaner is perfectly safe. Are All Water-Based RCFs (with Surfactant) Equally Effective? No. Let’s first review the likely surfactants used in water-based RCF. Though surfactants are generally effective cleaners, this effectiveness varies a great deal with the surfactant type (head), its molecular size and structure (tail), and the type of contaminant. Nonionic and anionic surfactants are typical surfactants used in RCF. Common nonionic surfactants are alkyl phenol ethoxylated alcohols. They naturally come as a broad mixture (Poisson distribution) of molecular weights and, for this reason, can accommodate a wide range of contaminants. For the same reason, they—more specifically one fraction of the nonionic mixture—can readily remove the plasticizer as well. Nonionic surfactants also tend to adsorb more on Vinyl surface. Common anionic surfactants are alkyl sulfates, alkyl or alkyl aryl ethoxy sulfonates and alpha-olefin sulfonates in increasing order of detergency. Alkyl sulfates are traditional laundry detergents, which tend to lose their effectiveness in cold water and in the presence of hardness (calcium). This shortcoming is rectified in the newer alkyl ethoxy sulfates. Alkyl or alky aryl ethoxy sulfonates are powerful synthetic surfactants. However, the length and branching of their tails must be tailored to the contaminants. For record cleaning, these ethoxylated sulfonates are more effective as a broad mixture. Alpha-olefin sulfonates are one of the most powerful and flexible commercial surfactants available. They work well at all temperatures and even in hard water. They can accommodate a wide range of contaminants and are excellent foamers as well. Their effect on the plasticizer may be minimized with a careful selection of the molecular size. Finally, cationic surfactants traditionally used as fabric softener and hair conditioner may also be used as a static suppressor. Note: The effectiveness and safety of commercial RCFs vary vastly depending on the surfactant(s) used. But unless their compositions are revealed, evaluation is difficult and speculative. Are Water-Based (Alcohol-Free) RCFs Completely Safe for Vinyl? Not necessarily. The ability of all surfactants to leach plasticizer from Vinyl has been grossly overlooked. As discussed above, surfactant molecules aggregate into small micelles that are capable of solubilizing plasticizers in their hydrocarbon cores. This ability is enhanced by the lower surface tension which allows the surfactant solution to completely wet the Vinyl surface, penetrate deeply into the Vinyl grooves and diffuse into the vinyl matrix to contact the plasticizer. So, even without alcohol, an RCF containing surfactant—possibly all commercial RCFs—is quite capable of leaching plasticizer out of your Vinyl if the RCF is left on the record long enough. (I found in an unrelated work, that surfactant solutions in water can leach out plasticizer from rubber and PVC sleeves. I switched to Teflon sleeves to circumvent this problem). Recommendation: With ALL RFCs, it is of paramount importance to remove the cleaning liquid from the Vinyl surface a quickly and as thoroughly as possible with a powerful vacuum. When Is A Preservative Not A Preservative? Preservative is one confusing term in RCF! It may refer to a compound in the RCF intended for “preserving the Vinyl” or to a compound in the RCF used to “preserve the RCF” itself (e.g. EDTA, which as we will see later is strictly not a preservative). What a mess! The term Vinyl preservative is a misnomer. Vinyl is an extremely inert polymer that needs no protection from chemical or biological degradation. Like many polymers, however, it is susceptible to UV degradation with long-term exposure to sun light. But unless you intend to play your LPs in a convertible roadster, the UV effect is irrelevant. The term Vinyl “preservative” may refer to other functions: 1) to minimize the loss of plasticizer, 2) to replace the lost plasticizer, 3) to lubricate or protect the Vinyl grooves, and 4) to change the sonic character of the Vinyl grooves. Should You Use A Lubricant Or Preservative For Vinyl? I am intrigued by the benefits of such treatment but also concerned about its deleterious effects. First, with the proper RCF and cleaning procedure, plasticizer leaching is not a problem and requires no remedy. Second, it is very difficult to choose a lubricant or preservative without a sonic signature. Third, a film of lubricant or preservative in the grooves may be bad for the record in the long run. The electrostatic attraction or hydrogen bond holding this film to Vinyl is probably not strong enough to survive the tremendous stress of the needle against the grooves: the adsorbed film (a few molecules thick) could be quickly shredded into contaminants clogging the grooves. The study of thin lubrication film is a difficult and highly specialized area of Science (tribology) that I am not terribly familiar with so I leave it up to you to make your own decision. For me, without more information, the safest treatment for Vinyl is simply to clean it and leave nothing behind. If studies of the long-term effect of lubricant or preservative exist, RCF manufacturers should make them available to customers to ease their concern. After all, we each own hundreds if not thousands of LPs, many of which are valuable or irreplaceable and some of us are understandably reluctant to use mystery chemicals whose short- and long-term effects on Vinyl must be taken on faith. Is EDTA A Preservative? EDTA has also been called a preservative, i.e., a compound that preserves the integrity of the RCF itself. EDTA is a chelating agent: it preferentially binds with polyvalent cations such as calcium, magnesium, and iron and keeps them from interacting with other active ingredients in the RCF, interactions that can cause solid precipitation. EDTA is generally used in complex mixtures such as hand lotion, hair shampoo, toothpaste, etc. where interactions with even minute amounts of calcium (from hard water, for example), can cause undesirable precipitation. EDTA may be loosely called a preservative only in this chemical sense, though the term chelating agent is far more accurate. EDTA is not a preservative in the sense of being a biocide or an oxygen scavenger such as sodium benzoate, ascorbic acid or sodium bisulfite. It looks like we have another unfortunate misnomer here. Summary Basic Concepts in Vinyl Cleaning Record cleaning is simple in theory but complicated in practice. Some basic concepts, chemistry and useful hints are summarized below to help you better understand the process and use RCFs effectively and safely: 1. To be effective, a record cleaning fluid must possess many properties some of which are mutually exclusive. An ideal RCF must be able to “wet” the Vinyl surface (alcohol or surfactant), “penetrate” deeply into the Vinyl groove (surfactant), and “dissolve” or “solubilize” contaminants on contact. It must also be able to “transport” (foam) solid contaminants away from the Vinyl surface and leave behind after vacuuming no residual film that may affect plasticizer and sound. A good RCF must not leach plasticizer from Vinyl during cleaning either, a side effect that can render Vinyl grooves brittle and susceptible to damage. 2. No single fluid can offer all desirable properties above. While water is the safest fluid to use, effective cleaning is not possible with water without additives. Most commercial RCFs include several cleaning agents—typically alcohol(s) or surfactant(s) or both—in water that provide the balance between deep cleaning and minimal harm to Vinyl. 3. All cleaning agents (additives) have their advantages and disadvantages. Alcohols (in water) evaporate easily and completely under vacuum, can remove a wide range of contaminants (by dissolution) but are not very effective at deep cleaning. Surfactants (in water) can provide exceptional cleaning (by solubilization). This effectiveness, however, strongly depends on the surfactant type, molecular structure and concentration and can be contaminant-specific. Just like alcohols, surfactants can also extract plasticizer from Vinyl with prolonged contact. Unlike alcohols, surfactants can leave a sonic signature if the residual surfactant film is not completely removed. 4. A carefully tailored mixture of several surfactants, or several alcohols or several surfactants and alcohols in water can offer a broad and deep cleaning without additional risk. When a minimal amount of surfactant is used (below its cmc), it serves only as a wetting agent, not as a detergent. 5. The contact time between RFC and Vinyl should always be minimized to reduce plasticizer leaching from Vinyl by either alcohol or surfactant. 6. All RCF ingredients adsorb on the Vinyl surface as a thin film that can be difficult to remove with vacuum. Unlike alcohols, adsorbed ingredients like surfactants are non-volatile and should be removed thoroughly with additional water rinse and vacuuming to avoid static and sonic changes. 7. Proceed cautiously with Vinyl lubricant, preservative and additives other than surfactants and alcohols. While they may offer sonic benefits, their long-term effects—sonic and otherwise—are difficult to predict and seldom studied or documented. 8. It is difficult to evaluate an RCF with unknown composition. Whenever possible, request a Material Safety Data Sheet (MSDS) for any RCF or household cleaner before using it. This is a good way to obtain the list of all the ingredients (active and inactive) and their potential hazards. Parting Shot It is my fervent hope this primer will provide you with the basic understanding to undertake the task of cleaning your treasured LPs with confidence and safety. As this piece was put together with some haste, your questions and help in pointing out the unavoidable deficiencies and errors will be greatly appreciated. Thank you for your time.