i have this same problem with gardiner brushes. thought it was just me. i have recently started to use gardiner brushes and poles 12 months. my opinion good poles but the brushes are pretty poop they take no real graft always know when we have been bristles everywhere!
It is recommended that any window cleaning brush is replaced regularly. I would personally recommend replacing an every day brush head every 8-12 months. Brushes are a consumable item much like a squeegee rubber is for a traditional window cleaner. Even if a brush looks in good condition the ends of each bristle will become pointed and less effective at cleaning after 12 months of scrubbing. The improvement upon replacement will be much the same as when replacing a worn out squeegee rubber.
alex,
i have tried to post the same pics that i sent to you,but the site wont let me, there is some wear to the stock, but it is not excessive and you are bound to get some wear to the edge of it asthat part will come into contact with walls, but the bristles have not been rubbed along a wall, the red spots on the pics i sent to you are not the remains of worn down bristles, what you can see is whatever holds the bristlees in place, the bristles do not appear to be held in place by epoxy or a strong glue, i can send you dozens of pictures of windows we have cleand with bristles sticking out of the window beading, another contributor to this post has said exactly the same, this cannot be right