Mike Simpson asks:

Mike,
I guess the best answer I can give you is to bring along a big container to dump the wastewater in and then dump out the water responsibly when you get back home or back to your hotel.

The same goes for cleaning the Palette, by the way. My wife makes me clean out my palette in the shop sink because if I do it in the kitchen, no matter how neat I try to be, a speck of cadmium yellow always shows up in the sink or on the pot scrubber.

Although some pigments such as titanium white are relatively inert in watercolor our gouache, it's hard to know what hazardous materials might be in an actual jar of wastewater. If you use cadmiums or cobalts, etc., there are going to be some toxins in the mix.

Some pigments can also stain a sidewalk, stone, or a ground surface, and that's not good. And appearances matter. Even if you know what you're dumping is innocuous, it may not look like that to someone walking by, or someone organizing the event. One artist in a group who accidentally drops their palette or dumps their wastewater in a sensitive location can wreck it for every other painter who comes later.

Also, some institutions such as colleges have to follow very strict OSHA rules. They get in major trouble unless every artist follows very strict clean-up practices, which involves designated buckets for wastewater. All this is even more important for oil painters who deal with solvents. So it's a good idea to ask around to find out what's OK.

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