The Scouring Post by Elaine Benfatto

(Elaine first posted this wonderful information on TechSpin, May 2004)

I've been very busy on some non-fibery work for the past couple of weeks so I haven't had time to check the list. But I just went through the past week or so of digests and have a few observations to clear up. Just to give you some background, I've been working for the past couple of years on cosmetic and body care formulation in addition to my fiber work, which means I've picked up a whole lot of basic biology and physiology, especially regarding skin and hair. This is directly applicable to the protein fibers with which we handspinners work. And I have spoken with several industrial chemists specifically about lanolin and lanolin derivatives, because it's family of ingredients I've been particularly interested in using in my products. First of all, there is only one type of lanolin. Lanolin is lanolin. It is a heavily researched and commercially valuable material that has been in use for centuries. It is defined as the greasy sebum secreted by sheep's skin and absorbed into the fleece as a skin protectant, water proofing agent, anti-weathering agent for the fiber, and such. It is a very complex blend of chemicals consisting of oils, waxes, free fatty acids (i.e. the chemicals that combine together into oils), sterols, and all sorts of other goodies. However, a fleece can contain many more things than just lanolin: suint (i.e. the water-soluble chemicals left after sheep sweat evaporates on the skin and fleece), fecal matter, pesticides (if not raised organically), plant matter, pollen, dirt, dust, and such. These can all combine with the lanolin and make different sorts of chemical soups that need to be cleaned. In addition, each sheep will have a slightly different chemical composition of their lanolin and suint: a different balance of waxes to oils, fatty acids, sterols, etc. So some breeds, like Merino, are notoriously waxy. Others, such as Coopworth, are a little more oily and less solid. So scouring wool is yes, always a challenge. And the issue always comes up around this time of year as the new clips become available and people work with wools they've perhaps never encountered before. So practically speaking, what's the best approach to take this stuff off the fiber you want to work with? Well, you need to consider the water-soluble and the oil-soluble parts of the job. The water-soluble bits are the easiest. Suint rinses out with cold water, as does dirt, fecal matter, and solid plant matter. If you've got a very grubby fleece, or a smelly one, or an old one with tarry tips... try giving it a cold-water soak. You need a container just large enough to hold the amount of wool you want to clean. Cover it with cold water, let soak. The water will turn a ghastly coffee-brown after a few hours. If you're really diligent, you can change the water once or twice. The cold water will not affect the lanolin nor will it remove all of the dirt, really. But it's like presoaking a really crusty frying pan: it'll soften up the gunge to make it easier to clean later on. Btw, fleeces that aren't particularly dirty can benefit from a cold-water soak but it's not essential if you want to save time. The next step is to attack the lanolin itself. You need to find a way to make the lanolin mix with the wash water and rinse away. There are two chemical processes that can do this: saponification and emulsification. "Saponification" means "soap making." If you add an alkali to warm fat, you make soap. Fat turns into soap, soap is water-soluble, so fat rinses away in wash water and incidentally carries dirt with it. It's an ancient process. And you can use this chemical reaction to clean wool. Washing soda (a.k.a. soda ash, sodium carbonate, etc.) is a strong enough alkali to saponify lanolin. So is borax. Baking soda is not. The problem is: protein fibers are damaged in alkali conditions. But since the wool is coated and protected by the lanolin, it won't be damaged by the high pH until the lanolin actually dissolves and leaves the fiber exposed. So! You could use hot, short soaks to saponify the lanolin as long as you get the fleece out of the water quickly enough to avoid damage. Twenty minutes or less is a reasonable amount of time per soak. The risk of damage to the protein fibers is minimal with such short exposures. The second approach to making lanolin water soluble is emulsification. This is the process that turns oils into little globules that can be suspended in water-based liquids. Emulsions are ubiquitous in our lives: milk, mayonaise, lotions, hand creams, salad dressings are just a few common emulsions. We also have emulsifiers all over the place, too: shampoos, dishwashing liquids, floor cleaners. Emulsifiers are also called surfactants. And a special subgroup of surfactants are called detergents, and are used for cleansing and to create foam. Orvus is a surfactant. The ingredients in your shampoo are surfactants. What is the difference between a soap and a surfactant? The soaps we use are always high pH. You can't have a low-pH soap. They clean through a chemical reaction -- by changing the fat into something new. Surfactants can be any pH, depending on the manufacturer's formulation. Most often they are neutral to high-pH. They clean through more of a physical process -- the oils and waxes are encapsulated and pulled away into the water, but they remain oils and waxes. For our purposes, pH is a consideration. It's better to use a neutral-pH than a high-pH product to clean wool, just because it reduces the risk of fiber damage. But! There's another consideration to using surfactants. Many surfactants are lousy at cutting grease. Orvus, for example, is a really lousy grease-cleaning agent. It was formulated to make foam, not to clean. When I tell cosmetic chemists that fiber crafters use Orvus (aka Sodium Lauryl Sulfate) to scour fleece they look aghast: "Does it work? SLS is terrible on grease." And the answer is no. It doesn't work very well. Sorry folks, but it really doesn't. Once you compare its performance to other surfactants, you'd see that it's pretty bad for anything but the lightest coatings of grease on a fiber. When industrial chemists formulate cleaning products with surfactants, they match the grease cutting surfactants (which normally have terrible foam) with foaming surfactants (like Orvus), and add other thing to make the product meet whatever goals the company envisioned. There are plenty of very efficient, neutral-pH, safe industrial surfactants out there that would do a nice job on scouring wool. The problem is that they're not available in anything less than 50-gallon drums. So we consumers are left with pretty pathetic choices when it comes to using surfactants to clean scour lanolin off wool: -- Shampoo isn't strong enough for the job. No way, no how. If you had a shampoo that could clean lanolin from a fleece, it would leave your hair so dry that you wouldn't be able to comb it. -- Dishwashing detergents can have some good grease cutters, but they can get expensive and they also contain a lot of foaming agents added because consumers equate foam with cleaning abilities. So they can be a devil to wash out. -- Automatic dishwashing detergents often contain bleach, which make them completely unsuitable for washing wool. -- Laundry detergents run the gamut. Some are based on surfactants, particularly the liquid ones. Laundry powders are more often based on alkalis and soaps rather than surfactants. Many laundry products are mixtures of both surfactants and alkalis, and also some ethylated alcohols. I spent some time going through the MSDS (materials data safety sheets) of something around 100 laundry detergents, because it is the only way to get some idea of the ingredients used in their formulations. (Manufacturers are not required to disclose ingredients of household products, but they do need to list substances on the MSDS to conform to OSHA regulations. And the National Libraries of Medicine maintains a huge database of MSDS by product and brand, to aid poison centers treat accidental ingestions. All this info is available online at http://householdproducts.nlm.nih.gov/) I found out that only high-end laundry detergents contain the "optical whiteners" that many spinners are afraid to expose their wool to. I did some research on just what these proprietary whiteners are at the manufacturers' web sites and it turns out they aren't anything particularly awful. They are kind of like white dyes, but they aren't washfast and rinse away the next time you wash the wool in regular old soap and water. But I also found out that many laundry detergents contain blends of enzymes to attack protein-based stains on cellulose fibers. These could be more problematic for protein fibers (enzymes seeing the fiber as a stain and starting to eat it!) so it would be best to avoid them if possible. Although, again, short exposures to such substances -- like the time needed to scour lanolin off wool -- isn't too problematic. I looked around for the most "surfactant-containing" detergents, so that pH wouldn't be such a problem and the cleaner would work by emulsification, not saponification. I have to say that the MSDS information was sketchy at best for most laundry products I saw, so I can't really say that I found solid results. But among laundry detergents, the most promising candidates for a good surfactant wool scour were: -Gain liquid -Bold liquid -Cheer powder -Cheer liquid -Era liquid -Ivory Snow liquid Now, I'm not endorsing these products because I still don't really know what's in them, nor have I had time to try them myself. But according to their MSDS (for what that's worth) they contained mostly surfactants and the least number of alkali or enzyme additives. If someone is systematically minded, they might want to do some tests, check the pH of a solution of the detergent and water, see how well they cut grease at which temps and concentrations, etc. Okay, okay, I've blithered for a long time and your eyes have all glazed over. Let me summarize: Lanolin is lanolin. There is only one lanolin that comes out of a sheep. It needs to be cleaned off by melting it in hot water and either saponifying it (turning it into soap) or emulsifying it (with a surfactant/detergent). Waxy lanolins are harder to clean and will need more heat and cleaners than oily lanolins. You can clean via saponification with use of an alkaline, like washing soda, borax, or laundry powder. Just take care to minimize the wool's exposure to the high-pH scouring water once the lanolin has dissolved from the wool. Bath temps at 140ºF, 15-20 minute soaks until the wool is clean. (Usually twice is enough.) Btw, the commercial washing sodas that I examined were 100% sodium carbonate with no bleach added. But you should look yours up in the database I cite above just to be sure. You can clean via emulsification with use of a surfactant, but we consumers have little choice of good ones for this purpose. You can try one of the brands of laundry products recommended above or dishwashing liquid. PH will most likely be less damaging, so you don't have to be so manic about the soak times. But they won't do an exceptional job and might take quite an effort to rinse out. Save your jug of Orvus for doing routine washing of your handmade wool items -- it's not a good wool scour. You can clean using both methods at once, with most of the regular laundry detergents out of there since they contain both surfactants and alkali. Whatever you use for clothing would work for wool scouring. But always assume it is quite alkaline and use short soak times. Even if there are optical brighteners and/or enzymes, they won't do damage to the wool until the lanolin is removed and can no longer protect the fiber. The final category of cleaners I haven't had time to explore yet in much detail. I'm beginning to see specialized scouring solutions marketed to spinners by companies like Louet. They appear to be surfactant-based and balanced pH. They are more expensive than the options above, but if they are more efficient and do a better job, they might be worth the savings in time and/or possible fiber damage. And for the truly adventurous (or those involved in large-scale production) you could approach textile manufacturing firms and ask about purchasing commercial wool scours used in industrial settings. So, I hope this is helpful. There's a lot of mythology out there in the land of handspinning, and I always find it interesting when I can actually research the science beneath and find out information that is truly relevant to our work. Happy scouring! Elaine