I knew that honey was an "old formula" but wasn't sure whether the paint needed any special consideration, so I emailed M. Graham. This was the response I had from Diana Graham (reprinted with permission):
"Most watercolor formulas have some form of sugar in the binder. The common one would be something like corn syrup. We looked to a time when artists made their own color and found the use of honey. Honey allows high pigment loads and contributes to smooth washes.
"Honey draws moisture from the air so our color always remains moist (sticky) in the watercolor palette even when exposed to open air year around. It does not get rock hard on the palette or in the tube like other brands. Just a spritz of water and they are ready to go.
"The down side is that if you have a very wet palette or are in a very humid place, transporting our color in a palette must be done flat rather than on its side or upside down as the moist color may crawl out of the pan.
"The other thing with our color is that you cannot paint thickly in a layer as it will stay sticky. If you want to do thicker painting or layering, we have a fine art gouache for that."