We all know that base layers have a tendency to get a bit stinky after a while. Even after washing they can have a slight hum to them, especially synthetic types. The problem is that ordinary washing liquids actually stop the synthetic material from wicking properly, which just exacerbates the issue.
Nikwax have a really good solution, in the form of Basewash and Basefresh. Basewash is designed to be used as a replacement for ordinary washing liquid for a load of baselayers, and it works really well, cleaning, deodorising, and revitalising the wicking properties of any baselayer. For a whole load of baselayers this is the product to use.
However, if you are adding baselayers to a load of other washing, use Basefresh instead of fabric conditioner, alongside your ordinary washing liquid to get the same results.
There’s a nifty little video here that explains all: https://www.youtube.com/watch?v=CmyqFDGeFXo
Or visit the Nikwax website for more details and other cleaning products: http://www.nikwax.co.uk/en-gb/productselector/cleaning.php