re adjusting "pH" for whatever...
Reading through today's queue (OK, forget the limerick),
it occurs to me that an old (inexpensive) tool, probably from Light Impressions could probably help, and who knows, maybe by now they've complicated it even better?
That was a "pH pen." You make a mark with it (felt tip) on the dry paper and get a (reasonable, as I recall) reading of the pH, according to the color.