Percentage Based Scour Method by Fossil Fibers and LongDrawJames

Now that we have spoken in depth about common scouring agents and methods by which they can be tested, we can present our method! We are very excited to share this with you. This method is based on using a percentage of scour to raw wool weight to strip the layers of contaminants off of the fleece. After testing the scours at 3% of their weight, we knew we wanted a little more power at the beginning of the wash process. This method uses 2 baths at 5% to do the bulk of the cleaning and then 3% until your water achieves a correct transparency that denotes the lanolin to be removed. This method does work with any setup preference you may have, be it baskets, bags, or washing loose in the water. Your main factors here will be soap choice, water temperature, water volume, and being able to monitor the appearance of your water. We have done extensive testing with the help of several other wool workers and many of our own fleeces over the past few months.

For myself, I use large sports laundry bags with an open mesh to wash a pound at a time in 3 gallon tubs and the slotted spoon shown to push the wool into the water so that it is submerged in the new bath. If I am doing something like sorted locks of a fine wool fleece destined for combing, I will put them in small lingerie washing bags or stacking mesh baskets that allow them to lay flat and contained instead of my large mesh bags. In between baths, I gently squeeze some of the excess water out so that less carries over into the new bath. You really do not want to squeeze too much or too hard so as not to cause felting. No other manipulation of the wool is done in my process and I have not come across felting problems in any grade of fleece. We are letting the soap and water do all of the work here. The photos below are all taken after this gentle squeeze.

Bath Progression from Cold Soak and Scour Baths 1-7

You can clearly see in photo one the dirt removal done by cold soaking a fleece. Again, we found this to only be a necessary step in fleece that is quite saturated with dirt and this can be skipped based on your own preferences. For baths 1 and 2, there is a strong opaque milky look to the water. This is something you really want to see in your scour baths as that appearance is the lanolin leaving the fleece and staying behind in your water. As the baths continue, the water regains its transparency and becomes quite comparable to the look of the water with soap only. I generally find 5-6 total scour baths using Unicorn Power Scour and then 2-3 rinses will be sufficient for most breeds. By now, I’ve learned to easily tell when I’m close to the end of my scour baths based on water appearance.

Soap Only, First Scour, Last Scour

It is really important to keep note of what this soap only look is for your wool wash to determine when is best to stop. It is entirely possible to damage, or “fry,” your fleece with excessive soap use. The clouding left in our last scour is not milky or opaque in appearance, but simply leftover dirt. I worry less about dirt leftover since it will fall out in all stages of processing, but you can continue to rinse your fleece after soap use is over to remove more dirt. This method of watching your water helps you respond to your individual fleece and use only the soap required to reach the results you want. Some may harbor more lanolin than others. Camelids do not harbor lanolin in their fibers, so a more mild approach can be taken for them. They could use a less powerful soap and less scour baths to achieve desired results. For instance, knowing from our test results that Kookaburra did not remove lanolin as we desired, but still removed dirt in an acceptable manner, our leftover Kookaburra will likely be our choice for washing our Camelids. Do note, higher temperatures can still help certain soap formulations perform at their best for cleaning these fibers. The method detailed below primarily pertains to sheep’s wool and oily goat’s fibers, such as Mohair. Knowing how to scour your own wool to desired results can be useful not just in your own processing, but in preparing your fibers for milling as well. Small mills typically charge a wash rate since it takes a significant amount of time to do so, and this can save you some cost there as well.

I’ve also found that in a small home operation, 1 pound per tub is a really manageable size. On fleeces with lighter lanolin content, I have gone up to 1.5lb per 3 gallon tub without error, but I wouldn’t do much more than this at a time. This keeps my water tubs light enough to carry easily and makes the amount of water needed to reach desired temperature is manageable as well. To reach temperature, my own tap water does not go much more above 120F, so I alter my water with 3 pots of water brought to a near boil on my stove. The number of which was determined by use of a thermometer and practice.

A spin dryer can be of assistance in reducing drying times at the end of washing. Truly, we use ours all of the time for everything from wet handspun to our fleeces. If using bags to wash, you can toss the full bag in the spin dryer, or unload it depending on preference. After running the fleece through the spin dryer, we lay it out flat in a well-ventilated room on an accordion rack that has window screens on it. This setup works for us, as we can collapse it and store it flat elsewhere until needed. Cotton bags make an excellent long term storage for washed fleece to give them breathability. You can even use old t-shirts with the arms and neck sewn up or old pillowcases. Improper wash or storage can lead to discoloration of your fleeces, particularly those that are white.

Our hope is that this eases any fears about learning to scour wool and helps improve the skills of others that already do. This method development was a long process that taught us so much about how our scour formulas work with our fleeces and water. I’m so happy we joined forces with James and were able to improve the end results of our washes. Since we sell washed fleece, this has helped us produce the best expression of every fleece we offer. The ability to customize our washes to each project and fleece was sorely needed! I knew there had to be a way that was not a strict blanket-coverage answer.

Special thanks to James Perry (LongDrawJames) whose assistance writing and in deciphering these scours was invaluable. And to our method testers Felecia Marottoli (one.wip.wonder) and Alissa Kuehl (foxysfiberwares). Your contributions and input have been so appreciated.

Scour Tools

Percentage Based Scour Method in Lab Protocol Format

Materials & Reagents:

2 plastic, or other material capable of withstanding high heat, tubs with enough room to hold a volume of water that is at least 3 gallons


Thermometer (a simple meat thermometer will do)

Measuring spoons

Dishwashing gloves

Scour of choice

Screen or mesh material for drying

Optional: Serving spoon for gently manipulating wool in hot water

Optional: Pans to heat water to specified temperatures

Optional: Mesh laundry bags or baskets to hold the wool with sufficient space for the wool to lie mostly flat

Optional: Spin dryer or fan. Spin dryer will greatly reduce dry times.


Day 1 if implementing a cold soak method

  1. Weigh your raw fleece.

Note: This will be important for determining how much scour to use.

  • Fill one tub with cold water.
  • Carefully place fleece into the mesh bags or basket and submerge in cold water overnight.

Day 2

  • Scours 1:
    • Fill the next tub with a volume of hot water (130-140 °F/55-60 °C) that is at least 3 gallons per pound of wool to be washed.Add 5% scour (based on the weight of your wool – See Table 1) to the hot water and mix with serving spoon. Alternatively, you can add the scour first and pour the hot water in second and allow the water to mix it as it fills.Carefully lift fleece out of its current tub and very gently squeeze out some excess
    • water without over-agitating the fleece. You may want to skip this for some fine wools. Be incredibly careful not to burn yourself!
    • Submerge fleece in the scour bath you just prepared for 10-12 minutes.

Note: Lanolin dissolves at temperatures above 120 °F/50 °C. Make sure your water temperature does not drop below this value. Your tap water may not reach desired temperatures, use pans heated on a stove to alter the water to the correct temperature.

Note: You may alter measurements from Table 1 into standard measurements by rounding up. i.e. 5% scour to 16oz of wool is 1.6tbsp. You may use 2tbsp in this easier.

IMPORTANT: It is important to keep the temperature consistent once your wool is in hot water as wild temperature swings from hot to cold will cause your wool to felt.

  • Repeat steps for Scour 1 once to complete Scour 2.
  • Scours 3+:
    • Fill the next tub with a volume of hot water (130-140 °F/55-60 °C) that is at least 3 gallons per pound of wool to be washed. Add 3% scour (based on the weight of your wool – See Table 1) to the hot water and mix with serving spoon. Alternatively, you can add the scour first and pour the hot water in second and allow the water to mix it as it fills.Carefully lift fleece out of its current tub and very gently squeeze out some excess
        water without over-agitating the fleece. You may want to skip this for some fine wools. Be incredibly careful not to burn yourself!
      Submerge fleece in the scour bath you just prepared for 10-12 minutes.
    • Repeat steps above for Scour 3+ until the water looks transparent as noted by the photos above in Bath Progression and no longer has a milky appearance from the lanolin.

Note: Then number of 3% scours will vary depending on how heavy the lanolin is in your fleece.

Note: Dirt will also come out in the scouring of your fleece, sometimes past your lanolin.

  • Rinses:
    • Fill the next tub with a volume of hot water (130-140 °F/55-60 °C) that is at least 3 gallons per pound of wool to be washed.Carefully lift fleece out of its current tub and very gently squeeze out some excess
        water without over-agitating the fleece. You may want to skip this for some fine wools. Be incredibly careful not to burn yourself!
      Submerge fleece in the rinse bath you just prepared for 10-12 minutes.
    • Repeat steps for Rinses until the water looks clear and the soap foam is gone.

Note: If for some reason you are unable to complete the whole process in one go, finish all scouring and move fleece into the first rinse. When you return, continue the subsequent rinses at the same temperature the first rinse has cooled to.

Note: If more dirt removal is sought after lanolin removal, continue with rinses until satisfied or pursue removal during your future processing steps. It is possible to over-scour your fleece and damage it. We are only seeking to use the scour to remove the lanolin.

  • Carefully lift fleece out of its current tub and very gently squeeze out excess water.
  • Optional: Place fleece in a spin dryer to remove further water.
  • Lay wool flat on a screen or mesh to dry. Alternatively, you can dry on towels, making sure to flip wool periodically.
  • Leave to dry for a 24-48 hour period.
  • Store dried fleece in a breathable fabric bag for best long terms results. Preferably cotton material.

Table 1. Scour volumes based on wool weight and % scour.

Wool Weight5% Scour3% Scour
8 (1/2 pound)0.82.411.
16 (1 pound)1.64.823.712.914.2
Lab Protocol Format contributed by Felecia of @one.wip.wonder on Instagram.

9 thoughts on “Percentage Based Scour Method by Fossil Fibers and LongDrawJames

  1. Thanks for all this info! I have some questions and suggestions.

    1) I would love to see your method compared side-by-side to the method recommended by Unicorn (for merino, 1 lb fleece, 2 gal water, 1 Tbsp scour).

    2) If the 12-hour cold water soak was fairly effective at getting dirt out, and you have a problem with dirt remaining even after lanolin, why not try longer initial soaks? I start mine in hot water and let it all sit for at least 24 hours. I’m not talking about suint fermentation here, just comparing 12, 24, 36, 48 hours. Soaks are so low-effort it would be great if it can be used to minimize rinsing.

    3) Any thoughts on why your results show a need for 7 scours when common wisdom is generally 2-4 scours for merino? I mean doubling is a significant difference! It’s not just because people prefer to retain more lanolin — experienced people are getting the same gorgeous results as shown in your last pic. Mynameisinigo on ravelry and Instagram is a great example.

    4) I’d also be interested in more information on comparing water amounts. Common wisdom and iirc some other tests suggest that more water is helpful, although less convenient!

    Thanks again for your research — I don’t mean to criticize, just to suggest other areas to investigate!

    Liked by 1 person

    • For sure! Let me respond to each of these numbered the same.

      1) This is the method that left me unhappy and seeking more information. I was always left with more grease than desired in moderate to high grease fleeces or odd “pockets” of concentrated grease in areas.

      2) I can definitely add info for longer soaks, but wouldn’t seek to do additional soak changes since we are also trying to reduce our water use where we can. I have left fleece up to 48hr and after that it absolutely begins to ferment. I have not seen a noticeable change in dirt removal for longer, but have not dried and weighed such results. I’d be more than happy to do so and add that in! At a 5% change for a 12hr soak, it is not quite as much dirt removal as I would hope and doesn’t take away too much of the load that the soap has to handle. I still prefer to cold soak because it IS helpful, but it might not be as necessary as it seems.

      3) This may be our water hardness also! Our results are purely based on what it took this hard well water to aid the soap in removing it. Likely if you have softer water, you will need less scours as well. Some of the soap becomes caught up in attaching with the calcium in my water, rather than attaching to the grease or dirt to roll it off the fleece. This is why we developed in a way that you can monitor your water relative to what it looks like is happening. Both so that you can customize what is left behind and get comfortable visibly seeing what lanolin looks like in water and what it looks like when it has left your fleece so that you know when to stop.

      4) I did not have any difference in scour counts between 9 gallons per bath and 3 gallons per bath per pound. We touched on the reasoning for the reduction in the testing methods post prior to this one. And 3 gallons was definitely preferable in hauling around such heavy buckets and in the sense of us seeking to reduce water use. If I went down to 2 gallons per pound, it started to add an additional bath to my process, so that is where we determined our barrier was. This can also be related to our hard water, I am sure, and you might find different results!


  2. Thank you so much for this amazingly well thought out and scientific method of scouring wool. I have in my own wool scouring journey come to many of the same conclusions. I just had none of the science to back it up. I always stopped short at the 2 to 3 scours with my super greasy wool. Much still has grease in it which has been making me crazy. I now know I should have kept going.


    • It really helps to have the visual representation of what lanolin looks like leaving the fleece and I found that so lacking before. That was a game changer in learning how to get comfortable in what I was working towards and not leaving it up to chance. I’m so glad this is helpful to you as well!


  3. Wonderful information in this series of posts; many thanks for doing this and sharing the results! I too have come to the conclusion that Power Scour works the best for me, although I didn’t have the rigorously derived data to support it. I do have a question that has been bothering me for some time and have tried to research it but didn’t have access to the information to answer it. I have heard it said a number of times by different spinning teachers (some of them quite well-known) that once lanolin is re-deposited back on the fleece during the washing process its chemical composition has been changed such that it is impossible to remove. Is there any science to back up this assertion? (Asking for a friend, because certainly this calamity has never befallen me in all my years of fleece washing 😉


    • I have also heard this and directed the question on to James, though he is quite busy and may not have time to answer. Personally, I would not think it chemically changed, but perhaps lodged more securely to the fibers because the act of the hot water means the microscopic scales are very open and let it settle in there. I could be entirely wrong and this is just speculation on why that may be. I do not have a background in chemicals or access to a lab to determine. I definitely want to let a sample cool in a bath with it’s lanolin and see what happens. The samples we ended up with here that were still sticky, did not incur a redeposit, they were just simply stopped earlier in the process. So they would work well to compare a cooled sample and the stopped samples against normal, unwashed fleece. So I do not have clear answers on how this works, just the same wonderings!


  4. Pingback: Identifying and Tackling Fleece Imperfections | Fossil Fibers

  5. Boiling water on the stove is a pain in my opinion. Based on someone else’s suggestion, I bought a water immersion heater to warm up the extra water for the next batch. It works great!


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