Glen Duff wrote in message ...
Don,

That is the test although the titrettor normally used with the vial is
not shown. It is a holder that is purchased separately and has a
lever-type action on the side and the cost is somewhere around $7 or $8.
I have never used the titrettes without this in the manner that is
shown in the picture. Perhaps others have done so.

I have never used a holder for the test. Pushing on the small ball
valve will suck wine in.

You break the lower end of the vial that is under a fine vinyl tube
always keeping the tip immersed in the wine once it is broken.

Not really required. If the little ball valve is not squeezed, nothing
will enter at least short term. I've never left one overnight to see
if the vacum is preserved.

A quick
release of the lever allows a small amount of the wine to mix with the
starch solution. You do this until there is a permanent colour change
from blue to a dark-grey or black.

Or to clear in the case of some white wines.

The level of SO2 in ppm's is
calibrated on the side of the vial and the more wine required to reverse
the colour the higher the SO2 level. Instructions come with the vials.

The more wine required to reverse the initial color change, the lower
the ppm of SO2.

Andy