So I never really thought about this before but it seems that group gaskets get a "memory" for different types of baskets. I just switched from the La Marzocco precision basket (basically non polished VST), to a VST 18g and low and behold the portafilter will not seal, you get drips.

The gasket isn't worn out by any means, portafilter locks in tight well before 6 o'clock, etc, but no matter how tight you lock it, you just can't get a seal with the new basket. I witnessed the same thing on my E61 machine.

Everyone else notice this over the years as well?

If the gasket is EPDM or NBR (black color) it will take a permanant set and any change in basket etc will usualy result in a leak. This is why the Silicone gaskets last so much longer as the black gaskets are being exposed to temperatures that reach or exceed the maximum allowed temperature for any long service life.

I do have a rubber gasket in, but I have a silicone in the drawer as well. I was at least mildly surprised that I ran into this since there is only tension on the gasket pulling a shot, between shots the portafilter is only in enough to not fall out, zero compression.

The black ones have minimal resiliency when fresh. Once cooked several times they take a set.

sluflyer06 wrote:I do have a rubber gasket in, but I have a silicone in the drawer as well. I was at least mildly surprised that I ran into this since there is only tension on the gasket pulling a shot, between shots the portafilter is only in enough to not fall out, zero compression.

I've often wondered whether it is best for the life of the gasket to keep the portafilter locked in for hours when the machine is hot or to remove it. I never thought of the option of keeping it in, but loose.

Matt

Maybe this is why our old espresso tech used to say 'baskets & gaskets,' that is- when it's time to replace your baskets, replace the gaskets at the same time.

That was on a 2 group La Pavoni in my old shop.

I would *think* the silicone gaskets would be better at not doing this, but I have only used them at home.

Also- if you're not a shop then go ahead and leave the PF out of the group. Put it in when you turn the machine on. If your machine is on a timer, well... I guess you can't really do that. My shop left the PFs in the groups during business hours, but overnight it's not necessary.

At this point in time, if silicone gaskets are available for your machine, it is just plain silly not to use them.