Modern outdoors clothing, shell stuff in particular, works brilliantly, but to carry on doing what it does, it needs to be looked after properly - contamination by dirt, oil, sun cream, expensive grooming products and so on, can lower breathability significantly.
The problem is that 'normal' detergents, the likes of Persil and Ariel, contain additives like optical brighteners and surficants which remain in the fabric and mask the factor water repellent treatment (DWR), once you do that, water no longer beads and runs off the surface of the fabric, which then 'wets out' and mullers breathbility.
The answer has always been to use specialist cleaners or, if you were on a tight budget, pure soap. The trouble with the latter is that it came as soap flakes leading to a bit of a palaver mixing up solutions for washing machine use accompanied by mucho anxiety over bubbling over episodes...
But no more, there's now a product called Liquid Soap Flakes, which is a liquid solution of pure soap, so should be ideal for washing waterproof fabrics, soft shell garments and anything else that's on the delicate side. It retails for around £3.00 per bottle and each bottle should give around 15 washes, which makes it significantly cheaper per wash than technical cleaners, even though they do work well.
We'll give it a go shortly and report back - the instructions on the bottle suggest making sure the drum of the washing machine is at least half full to avoid impromptu Ibiza-like foam parties, otherwise you just follow the care label on the garment as per usual.
One final point - pure soap is great, but bear in mind that some contamination survives contact with it quite happily, so some fabric brands including eVent and Paramo, suggest you may need to - sometimes - wash using normal detergent before either re-washing with a soap product or simply double rinsing to remove all contaminants.
Liquid Soap Flakes are produced by DRi-Pak - www.dri-pak.co.uk - and a 750ml bottle will set you back around £3.00. It's stocked in Tesco and other stores. Laundry verdict to follow.