Radish triage: separate your paintable radishes into a few bunches, give them a quick cool rinse and pop them into 3 separate plastic bags, then into the fridge. When ready to paint, (palette scraped and ready, paint laid out, etc.) take out one bag and plop it down and GO. You have about 20 minutes before the radishes bleach out to a cadaverous pink. As soon as the painting is finished, rinse the radishes put them in the bag, then back to the fridge. Take out another of the first set of radishes and start on painting # 2. And so on. If you make it to the second day, your radishes will all be dewy and fresh. Moisture is everything.