So what's the reason that a laser must cut a hole just prior to insertion
into the can? I don't see any explanation for that. If the other things
you say are true, then the "hole" can be manufactured at the same time
the rest of the widget is - no need for any laser on the filling line.

: Fred:

: Mechansim is quite simple, before the beer is placed in the can (or bottle
: or keg), it is carbonated and nitrogenated to precise levels in a holding
: tank. Here in the USA this tank is known as a bright beer tank. As the
: empty cans/bottles move down the conveyor toward the filler, a special
: machine places a widget in each can/bottle. The widget is esentially a
: hollow plastic sphere or other shape, and other than holding the widget in
: place in the can I don't believe that the shape has any major role. However
: the secret is that just before the widget is placed into the can a laser
: cuts a hole of a precise diameter in the widget. The can is then filled and
: sealed in the conventional manner.

: After sealing, the higher pressure in the can relative to the inside of the
: widget results in the widget filling with the beer until the pressure inside
: the widget reaches an equilibrium with the rest of the can. Things then
: remain stable until the can is opened. When the can is opened, the pressure
: in the bulk of the liquid falls, faster than that of the liquid inside the
: widget. As a result of this differential pressure, the liquid in the widget
: squirts out through the orrifice, this sets up shear forces that strip the
: nitrogen from solution in exactly the same way as the restrictor plate is a
: "stout faucet" does. The nitrogen forms the dense creamy bubbles that give
: the characteristic creamy head.

: As for making all beers taste the same, I believe that this is a side effect
: of the niotrogenation. My experience is that the nitrogen tends to strip
: hop bitterness from the liguid into the head. I know this sounds gross, but
: use your finger to scoop out some of the head and taste it, typically it
: will be bitterer than the liquid, hence the beer will have that same
: relatively bland smooth taste.

: Iechud Da - Cwrw42


: "FredG" wrote in message
: om...
: Greetings all.
:
: How do the plastic inserts (widgets?) in draughtflow cans work? Also
: is it an additional function of these things to make all beers taste
: the same or is it just me?
:
: Thanks.