The addition of ethanol, which is fully miscible in water yet, less polar than Water reduces its solubility. This reduction of solubility results in precipitation of least soluble salts first or the salt which is not soluble in solvents less polar than water.
Pole pockets on banners are something that can cause a bit of confusion. This is compounded by the fact that some companies do things differently when producing banners with pole pockets.
The 'Cadillac' of power poles is made by a company that goes by that very name - 'Power-Pole'. Their slogan is great, Swift and Secure. This $1,600 model is the one used by well financed sport fishermen and, believe me, none of them would be without one of these devices on their boats.