Randy G. wrote:I think that brushing the shower screen is overrated, and can easily be more detrimental than helpful. Flush some water through after removing the portafilter then just wipe with a towel. Using a brush is just as likely to shove coffee into the screen as removing it. I have a set of towel I us for coffee and I wet the corner and throw it over my shoulder before beginning a session. It is used to wipe the steam wand after the milk jug is removed, I wipe the shower screen with it, and also run it around in the group to clean the gasket after brushing. So, IMO, the fins on brushes are not necessary. On the other hand, cleaning of the gasket is very important. It helps maintain a good seal with a minimum of tightening of the portafilter, and it extends its like.
I have to disagree with a couple of things.
1. I've never had a group brush force coffee up into the screen.
2. I like to use separate towels, one for wiping milk / wand and one for wiping group / portafilter.
3. The purpose of the fins, like Chris said, is to prevent hot water from running down the handle and burning your hand. I think it's an essential feature, unless you completely avoid running the pump and brushing at the same time.
But you do make a good point that one shouldn't neglect cleaning the gasket.