Method and Results of Testing Common Wool Scouring Agents

Power Scour Washed Locks

Now that we have the basics and chemical analysis down from our previous post, let’s go over our testing methods and results. With James’ help, we devised a standardized, scientific procedure for this and I performed the tests. We were very careful to keep everything constant and we only changed one variable at a time. Using the same water and apparatus for each wash, we also ensured that the wool used came from the same South American Meat Merino Ram fleece. This boy was exceptionally fine, dense, sticky, and a bit stinky which made him perfect for putting these scours through their paces.

Evaluating Maximum Wash Potential

One piece of data we needed to carry out this investigation was the mass of grease in the raw wool. We used this as an opportunity to test the maximum cleaning potential of each of the scouring agents. To do this we used a very simple wash method. 1.97oz or 56g fiber was placed into a mesh bag and soaked for 12 hours in cold tap water prior to wash. Water of 140F/60C was added to a basin and 3% (by weight of raw fiber) detergent was added. The mesh bag was added into the basin and this was left for 10 minutes to reduce water cooling effects. The bag was then removed and the wash cycle repeated until no more lanolin was evident in the scour bath, which is evident by clouding or opacity of the bath. The rinses were carried out using the same 140F/60C water in the same way as the washes, but without the addition of any detergent. This method was expanded on and will be detailed in the next post clearly.

Raw vs. Rinsed

To begin, the pre-soaked weight of the fiber was calculated. This was found to be 51g, which represents just a 5g, or 8%, decrease in weight from each of the samples. This decrease would be due to removal of some soluble components of the wool contaminants, being mostly suint and dirt. The remainder of the dirt is likely either “locked” in with the lanolin or is lanolin itself, which represents the need for the scouring agent combined with the hot water as we spoke about in the previous post. This did tell us that dirt removal by cold soaking can be useful, but is not entirely necessary prior to scours. The dirt removal is visible in the photo above, but will likely be removed by direct hot scouring without much more effort. However; if you have an exceptionally dirt-laden fleece, cold soaking is going to be very useful. You will see a larger temperature drop taking wool direct from a cold soak and into a hot bath. This can be mitigated doing a hot plain water bath in-between the cold soak and the scour baths. You can take wool from extreme cold to extreme heat safely without felting occurring. The microscopic scales on the wool surface act as a ventilation system, closing when cold and opening when hot. Felting occurs when the hot, open scales intermesh and then are closed quickly with cold or by too much agitation while wet and you should always handle wet fleece with care.

James tends to scour using a given mass of surfactant calculated as a percent of the mass of wool and we worked on developing an easy method with this. One can more accurately determine the right amount of surfactant for the bath type used with this method. Higher percentage of surfactant will generally clean more than a lower percent, but this increase is not always linear, so 2% may not clean twice as well as 1%. 3% for these tests was determined to be an easy, base measurement to go by across the board for our chosen products so that we could really pit them against each other equally instead of following their bottle instructions. Each portion was weighed on a microgram scale to be as exact as we could.

Dawn Ultra, Raw, and Unicorn Power Scour in comparison

Of the results, in fact, the only sample which demonstrated complete grease and dirt removal was that of the Unicorn Power Scour. The remaining weight after scouring was 35g which constitutes a 37.5% change in mass due to dirt and lanolin. Power Scour was also able to remove the contaminants using the fewest washes and rinses, though Dawn Ultra was a close second. We found Dawn Ultra removed nearly all of the lanolin with a small amount trapped in the very tips of the fiber that could be felt when dry. It did leave noticeable amounts of dirt in the wool, constituting a slightly lower mass change of 30%. It also required more washes and more rinses to get to this point, but not by much. You can see the comparison above to note the trapped matter in the fleece tips. Truly, it is not much and we were impressed with Dawn Ultra’s results.

Orvus Paste Max Scour Test Results

For Orvus Paste, even after 9 washes, the fiber still did not show total grease removal as expected, rather removed 21%. For a very low lanolin fleece, this may perform acceptably for you. By far, the number of washes and rinses was greatest though. Orvus also showed a lot of foam which was very difficult and stubborn to rinse out. This is somewhat unsurprising due to the major component being Sodium Lauryl Sulfate(SLS), which is well known to have a very high foam potential. Due to this excessive numbers of rinses and washes for such a poor removal, we chose to eliminate Orvus altogether from the next regiment of tests since it was performing as expected and the next set of tests was about grease removal percentages per bath. Kookaburra, perhaps most surprisingly, was the poorest on performance and we actually could not seem to give the fleece enough baths to remove appreciable amounts of grease no matter which avenue we approached. You can visibly see the lanolin in water as it is very opaque and milky. This was not visible in the Kookaburra baths and we would have spent an exceptional amount of time trying to net a grease-free fleece. As a result, we omitted these results from this table of maximum grease removal entirely.

Water hardness may have been a factor for Kookaburra’s performance problems as it should have net some results based on its chemical make up and this may not have shown it justice. It does take to note, that if you do have exceptionally hard water as the testing water was, this brand may not be the one to go with. Water hardness is well known to influence the performance of many surfactants, especially anionics such as SLS like Orvus Paste uses. Above are the 16 point basic home water testing kit results for the water in these tests. We found that the calcium carbonate level of the well water was 180ppm. In general, water with less than 60ppm can be considered soft, water with 60-120ppm is moderately hard, and water with greater than 120ppm is hard. This could be one potential reason for the poorer performance of Kookaburra and Orvus since they do not contain any softening or chelating agents which would improve their performance under these conditions, whereas Dawn Ultra and Unicorn Power Scour do.

Cleaning Potential Per Wash

Kookaburra Tests

After carrying out the evaluation of maximum grease removal, we chose to investigate the correlation between grease removal and number of washes. To do this, we followed the same procedure as for the washing tests, but removed the surfactant factor after the designated bath number, rinsed as normal, and dried them so that we were able to see the effect of each wash on grease removal. We tested this over 4 different 56g portions per product. Doing this yourself, you may be able to dial in an exact percentage of grease you want to see left in each fleece if your goal is to have some lanolin left in your wools. The below table could also be a good starting point to see those results as well. You can always wash dried fleece with higher lanolin from such tests additional times, so doing this should not net you wasted wool.

The results of the grease removal per scour bath were calculated based on the max scour weight from the Unicorn Power Scour sample in figure 1 (35g). This was most likely as close to totally de-greased as we were able to calculate without lab testing. The grease removal for each sample was then calculated as a percentage of this value.

Instantly from the data, we see that Unicorn Power Scour overall removed the largest amount of grease. It also was able to remove more grease in the first wash than either of the other scouring agents were at approx. 54% removed in the first wash. This is almost comparable in first wash terms to Dawn Ultra which removed 50%. As we discussed, our Kookaburra under performed likely based on our water and you can see it was able to only remove 24% of the grease in the first wash.

Where Power Scour really shows strong performance is in the second wash where it removed a further 30% of the grease compared to Dawn Ultra which did not show a significant increase in grease removal and plateaus quickly. Kookaburra was able to remove only an additional 5% of the grease.

After the second wash, all three formulations showed a small increase in grease removal, and were all relatively comparative. Overall, Power Scour removed a total of 84% of the total grease in 4 washes compared to Dawn Ultra which removed 54% and Kookaburra which removed 37%. This data clearly shows a strong outperformance by Power Scour relative to the other formulations and translates well into the Max Scour Data above. When water usage is in question, Power Scour shows we are using less to accomplish more and when we wash as much fleece as we do here, it is a huge deciding factor. Again, Dawn Ultra showed to be a close second in the Max Scour Data. Below, you can see each sample easily compared between our two main competitors. The 1st, 2nd, and 3rd samples remain quite sticky in each. By the 3rd in Power Scour, we have markedly noticeable difference in feel, and by the 4th in Dawn Ultra.

Power Scour Tests
Dawn Ultra Tests

Speaking of the water usage, we also tested at a later date from these, just how far down we could go in water to wool volume and still maintain the results with Power Scour. Initially, we would wash fleece in nine gallon tubs to one pound of wool. This was of course, physically taxing and having this be easy and accessible is important. Our waste water with Power Scour, since it is largely biodegradable, goes directly into a flower garden as fertilizer and we have questionable plumbing that may take offense to the lanolin being poured down the drain. This is not something we could do with Dawn Ultra, which has environmental toxins. We have seen exceptional results in blooms since we wash so many fleeces. One lily plant went from producing an average of 4 blooms in a year to 18 blooms which was wild and unexpected! However; hauling around heavy nine gallon bins wasn’t the best. Playing with water volume, we found we could reduce it down to three gallons per one pound of fleece with no interruptions to scour performance and it has greatly eased the taxing effort of washing our fleeces.

Discussion of Results

Power Scour at Max

As discussed, Power Scour was able to remove the greatest percentage of total grease followed by Dawn and lastly, Kookaburra. Power Scour’s excellent performance is somewhat expected based on our experiences with this blend, and its formulation. It is mostly non-ionic based, which is very effective at grease removal, and with the addition of anti-deposition agents, which prevent re-adhesion of lanolin to the fibers, it makes sense that more lanolin remains in the water relative to the fibers. Power Scour is also quoted at operating at lower temperatures than the other detergents, hence it is likely that the temperature used corresponds to the optimum temperature for this surfactant blend. Despite being familiar with the product prior to these tests, we were still impressed by how white and soft this very saturated Merino came out and are sure that is evident in how we have been writing about it.

Dawn Ultra at Max

Dawn Ultra is not optimized for wool, but is optimized for grease removal and specifically plant oils and animal fats which contain some of the same component waxes and oils as lanolin. It is unsurprising that the formulation does work to degrease wool, but does not contain the same blend of non-ionic surfactant and rather a higher proportion of amphoteric and anionic. These are shown to not work quite as well in hard water and with the lack of anti-deposition agents it is possible that some of the grease may have re-deposited or some of the surfactant was occupied in chelation with calcium ions in the water. This may explain some of the lanolin feel in the fleece tips. It is also worth noting that the Dawn Ultra example did feel mostly grease-free in the hand despite the lower grease removal percentage. It is possible that the sample of wool used either didn’t contain as much grease, or it is possible some of the grease re-deposited to form a microfilm over the fibers. This is not entirely clear and is very hard to analyze without access to a lab and some different solvents for testing. Overall, this was a very nice and acceptable resulting fiber and a close second to our Power Scour results.

Kookaburra Comparison at 4 scours

Kookaburra, whilst optimized for de-greasing wool, seemingly does not perform nearly as well as Power Scour or Dawn in very hard water. The surfactants used in this formulation are alkyl glycosides, fatty alcohols derived from fatty acids, predominantly. These are well known personal care surfactants and are known to be very mild. However, it is possible that this mildness hinders the cleaning potential. Likely, hard water should have marginal effect on these surfactants due to their non-ionic nature, but we cannot be sure ours did not. It may also be that this surfactant just is not capable of removing higher amounts of wax components, sterols, from wools such as the Merino wool used in this study. We will likely test this again on a fleece that is easier to scour since Merino can be more difficult to scour and we would like to puzzle out the answers here.

Orvus Paste at Max

Orvus Paste definitely performed as anticipated based on its formula with a really decent amount of dirt removal and low grease removal. As stated in our previous post, this formulation is used to wash animals prior to shows, and it does that job well. You don’t want to remove the lanolin off of the live animal as it may cause skin, fleece, and health damage.

As a cost for product analysis between the two products that worked best for us on lanolin removal, at the time of this article, Power Scour comes in at $1.23/fl. oz and Dawn Ultra at $1.71/fl. oz. At max scour by the results here and in the method detailed in the next post, we would have used 4.5fl. oz for one pound of fleece in Power Scour and 5fl. oz of Dawn Ultra. Making Power Scour $5.53 per pound washed and Dawn Ultra $8.55 per pound. A tablespoon, which is the closest standard measurement we will be using, is .5fl. oz, which makes this easy to calculate for your own as well.

In closing, we determined Power Scour is the right product for us, but we hope this data lends some clarity for your own reviews and tests as well. We know that everyone finds a product that they hold dear and works best for them and their home water. We encourage you to do the same methods of experimenting and investigation of your ingredients if you are looking to learn more about your products or scour methods that pertain to wools. This taught us so much and was really invaluable information for how to carry on with our future washing. Finding a way to wash fleece that was effective and easily modified to preference while also taking the scary out of washing wool was so important and I am beyond happy we carried this project through and are able to publish it freely for your use as well. This is the type of skill-sharing our wool communities are so good at and need to grow together. In the next post, we will be sharing the wash method we developed in detail and with plenty of helpful photos to go by. Thank you so much for following along!

7 thoughts on “Method and Results of Testing Common Wool Scouring Agents

    • Oh gosh yes! Mine is terrible. I commiserate! Likely those with softer water will note they require less washing than we do. Our soaps get bound up in attaching to the calcium instead of being able to do their job.


      • I was told once I would never get my fleece free of lanolin. Mine does usually ends up sticky on fine fleece. I have only used Dawn. I will probably need to try Power Scour. Thanks again 😎

        Liked by 1 person

  1. It’s still the Planet dish soap for me. Non enzyme, and biodegradable. I am not a fan of Unicorn, for various personal reasons. Planet exceeds Unicorn.


    • Completely fair! Everyone has their own preferences and different products will work best in different water types. That’s why we set out to make the testing methods public as well so people can figure out what works best in their homes and customize their scour as well.


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