Many American recipes involve diluting vinegar with water and then processing the jars. Dilution reduces vinegar's acidity, necessitating the jars to be processed to prevent bacterial growth. However, in this recipe, we use undiluted 5% vinegar, boiled with spices, and poured over cucumbers - no water involved. This makes the pickles more sour (which pairs well with winter roasts) and keeps bacteria at bay. The pickles need 3-6 weeks to be ready, and since the vinegar is not diluted, there's no need for processing. In short, if the acidity of pickle juice drops below 3%, a water bath is needed. If the acidity stays around 5%, it isn't necessary.