Raw Fleece Scouring Yield Calculator
Enter your fleece weight and breed to find out how much clean wool you will have after washing, how much water and detergent you need, and how many yards of yarn you can expect to spin. Everything runs in your browser - nothing uploaded.
Scouring Results
Scouring Steps
- 1 Fill a basin or tub with the calculated water volume at 60-65 C (140-150 F). Hot water is essential - it dissolves lanolin. Do not use boiling water as it can felt fine wools.
- 2 Add the detergent and stir gently to dissolve before adding fibre. Power Scour and Unicorn Fibre Wash are both low-suds, fast-rinsing formulas ideal for wool.
- 3 Submerge the fleece and press gently to saturate. Do not agitate or scrub - movement plus heat plus soap causes felting. Leave to soak for 20-30 minutes.
- 4 Lift the fleece out without wringing. Drain the basin, refill with water at the same temperature, and rinse the fleece by soaking again for 10-15 minutes. Repeat once more if the water still looks very dirty.
- 5 Gently squeeze out excess water, roll in a towel, and press to remove moisture. Lay flat or hang in a mesh bag to air dry. The scoured weight shown above is what you should expect once fully dry.
Fleece yield, scouring loss, and yarn calculations
How breed yield percentage affects scoured weight
Raw fleece from sheep contains grease, dirt, and vegetable matter that wash away during scouring. Each breed retains a different percentage of its raw weight after cleaning. Merino fleece is approximately 30-40% yield, meaning 5 pounds of greasy Merino becomes 1.5 to 2 pounds of clean wool. Romney, with coarser fibers that trap less lanolin, typically yields 50-60%. The calculator uses standard breed yield percentages from industry sources. For example, 2 pounds of greasy Corriedale (60% yield) becomes 1.2 pounds of scoured fleece ready to spin.
Water and detergent scaling based on fleece weight
The amount of water needed for scouring scales proportionally with fleece weight - roughly 200 liters of water per 100 grams of raw fleece. Detergent concentration stays constant at 3 mL per liter of water when using Power Scour or Unicorn Fibre Wash. This ratio ensures that soap molecules can dissolve lanolin without over-sudding or under-cleaning. Under-dosing leaves grease in the wool; over-dosing wastes detergent and requires more rinsing. Always prepare water at 60-65 Celsius (140-150 Fahrenheit) before adding detergent - hot water is critical for dissolving lanolin, but boiling water risks felting fine fibers.
FAQ
Why do different breeds have different yield percentages?
Coarser, shorter-staple breeds like Jacob and Shetland shed dirt and lanolin more easily during scouring and retain 55-65% of their weight. Finer, longer-staple breeds like Merino have dense lanolin and trap more dirt, yielding only 30-40%. The difference reflects the breed's natural fiber structure and the amount of grease the sheep produces - not a failure of washing, but a real material property.
Can I scour fleece with less water or less detergent to save time and money?
Reducing water shortens time but leaves grease in the wool, which causes sticky, unpleasant texture and poor dye uptake. Reducing detergent similarly fails to dissolve lanolin evenly. For reliably clean fleece, follow the calculated amounts. If cost is a concern, consider smaller batches using the same proportions, or accept that leftover detergent is a sunk cost of the process.
How accurate is the yarn yardage estimate?
The estimate assumes even, consistent spin at your chosen WPI (wraps per inch). Real-world yardage varies based on how tightly you spin, whether you double or ply the yarn, and how much the yarn felts during washing. Many spinners get 10-20% more or less yardage than the calculator predicts. Use it as a rough guide, not a guarantee.