Stop at the permanent color change.

Can someone please give me insight regarding the end
> >> point color I should be watching for? A red will gradually turn to a
> >> reddish-gray,

The Europeans use 7 as the endpoint, North Americans use 8.2. I have
noted it's not that big a difference just as Greg mentioned, the PH
really takes off around 7. I use 8.2


> > using a ph meter to check for the end point takes all the guess work
> > out of the end point. many on the board have said that the endpoint is
> > when you measure a ph of 8.2, however, my bottle of blueing solution
> > says to measure to 7.0 so that's what i do.
>

....> Using a pH meter to titrate would be a
> preferred method with reds. Generally we titrate to pH 8.2 because that is
> the pH at which phenolphthalein changes color. Thus, it would be consistent
> with colorimetric titrations. I think the difference between pH 7 and 8.2
> during the titration is a matter of just a few drops anyway (the titration
> curve is very very steep at the point of neutralization of the acids).