Ga.Modeler,
not sure which exact windsor & newton cotman colors you are using.
my are supply store seems to have 3 or 4 'grades'.
i get the cheapest and they are 2 to 4 dollars a tube.
i guess whether that is 'cheap' or 'not cheap' depends on your wallet & expectation!
:-)
Martian,
not that you asked me, but i have lamp black, grey, burnt sienna and some kind of ochre
for washes.
blue, green, yellow, red to make filters.
considering how they are used, if there are choices within a color,
i buy the lowest price one!
yeah, DJ, what does the vinegar do?
and is it white vinegar or cider vinegar?
ed.