Preheat the oven to 400°. While wearing latex gloves, long sleeves and safety goggles, fill a large, deep ceramic, plastic or glass bowl with the lukewarm water. Carefully add the lye (always be sure to add lye to water, never the other way around) and, taking care not to splash, stir the solution occasionally until all the beads have fully dissolved, about 5 minutes. Using a slotted spatula, gently lower a pretzel into the solution for 15 seconds. Carefully turn the pretzel over and soak it for another 15 seconds. With the spatula, remove the pretzel from the lye solution and return it to the baking sheets.