White runners yellow for three reasons. Detergent residue. Oxidation from drying in direct sunlight. Dye transfer from a coloured wash bag.
You can solve all three.
Residue. Use a small dose of liquid detergent for delicates. Half what you would use for a load of clothes. No bleach. No powder.
Oxidation. Dry your runners indoors, in indirect light. Direct sun is the fastest way to yellow white textiles. A 24-hour indoor dry is worth more than a 4-hour sun dry.
Dye transfer. The wash bag matters as much as the wash. A yellow or dark green polyester pouch will transfer dye onto white shoes over multiple cycles. The Shoe Wash Kit is built chalk inside and out, tested to ISO 105-C06 grade 4 colour fastness, so this third source is closed off.
Full method in our Care Guide. Launching July 2026.