Unlike standard wool garments, Esker foundations utilize felted wool. This is a non-woven technical textile created by interlocking wool fibres into a dense, multi-directional matrix. This process results in a material that is structurally resilient, naturally dampening, and—crucially—will not fray when trimmed to fit your footwear.
However, because felted wool is a "live" protein-based material, it remains reactive to its environment. In this Field Note, we examine how to maintain the calibrated density of your insoles without triggering further, unwanted structural changes.
1. Preventing "Over-Felting" (The Shrinkage Risk)
Your Esker insoles have already undergone a controlled felting process to achieve their specific density. However, exposing them to high-velocity agitation and high-heat in a domestic washing machine can trigger over-felting. This is where the fibres continue to interlock and tighten, causing the insole to shrink, harden, and lose its ability to thermoregulate.
The Field Observation: Always prioritise a gentle hand-wash in cold water. By avoiding the mechanical stress of a machine cycle, you preserve the precise thickness and "breathability" of the felted matrix.
2. PH-Neutrality and Lanolin Preservation
The strength of felted wool lies in the health of the individual fibres. Wool is naturally coated in lanolin, which provides both antimicrobial properties and water resistance. Aggressive, high-alkaline detergents break down these natural waxes.
The Field Observation: Use a PH-neutral liquid detergent. This removes surface salts and dirt while leaving the lanolin intact, ensuring your insoles remain soft and effective at managing odour for the long term.
3. Thermal Stability of the Latex-Infused Core
The felted wool in an Esker insole is bonded to a latex-infused arch core. While felted wool is incredibly heat-resistant, the adhesives and natural latex used for support are thermally sensitive.
The Field Observation: Never utilise a tumble dryer. Intense heat can cause the latex core to become brittle or warp, compromising the anatomical support of the longitudinal arch. Air drying is the only way to ensure the insole's "memory" remains intact.
The Field Maintenance Protocol:
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Extraction: Remove the insoles from your footwear.
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Surface Clean: Use a soft-bristled brush to remove dried mud or grit from the felted surface.
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Submerge: Submerge in cold water with a small amount of neutral wool-safe detergent.
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Compression: Gently press the water through the felted matrix. Do not wring or twist, as this can distort the internal arch support.
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Reset & Dry: Rinse in cold water. Lay the insoles flat on a towel to air dry at room temperature.
The Verdict
Felted wool is a masterpiece of natural engineering—dense enough for high-torque performance, yet porous enough for total thermoregulation. By following a technical care protocol, you ensure that the "active" properties of the fibres continue to perform through every season.
