Originally Posted by
Logistics
There are some videos showing members lathering. If you watch carefully you can see when they add water when it's too thick.
Thick lather that needs water has little to no suds or foam in the bowl when lathering. If you advance to applying that lather to your face it will be easy to figure out as the lather will dry before you are half done. If the lather is drying on your face you needed more water while lathering in the bowl. In a sense the lather will make your face look like the Mona Lisa before you're half done shaving.
Thin lather, watered down, generally has a itty bitty pool of water at the bottom of the bowl. If you pay attention to the lather it will also have larger bubbles and when you get a little peak (think meringue pie peaks) and it folds over, this means you need to lather it more. Just keep going swirling the brush making lather but do not add more cream/soap. Also, if you advance to applying the lather to your face the lather will make a sound like Rice Crispies (popping of the bubbles) and can be a little translucent.
Ideally you want the lather to be thick-ish. Think meringue pie peaks except the peak will not fold over if the brush is held vertical. The lather doesn't dry up quickly when shaving leaving you with a crust like appearance. You cannot see through the lather and doesn't make the Rice Crispies (bubble popping sound).
When I mentored a friend I recommended he practice lathering frequently even if he wasn't going to shave. Use a cream that isn't super expensive such as Proraso or CO Bigelow. Lathering is somewhere between a science and art.
This is just my experience and I'm sure others will have more information. :)