Brewers:
I had been warned about scratching a PET 'boy if I used a plastic bristle brush, so I didn't buy one. Yesterday, I had to rack....was getting late in the primary. After, I have the inch-wide band of brown yeast that even 1-Step wouldn't dissolve. In desperation I stuffed a pad of kleenex in, added water and rubbed the little buggers off the wall with a Swiffer handle. It's all plastic, so should be soft enuf. One improvement would be to use a piece of cotton cloth, as kleenex contains wood products, but cotton is all cellulose. Your mileage may vary.