First, make sure to follow these precautions! http://www.vingle.net/posts/455129
1. Select a large stainless-steel pot tall enough to cover pretzels by at least 3 inches, and at least 3 inches wider than the pretzels as well.
2. Fill the pot with 6 cups (1.4L) of water.
3. Wearing gloves, add the lye 1 tbsp at a time (the amount will depend on the recipe).
4. With the hood vent on, warm the lye solution over high heat just until you see wisps of steam, and then remove the pot from the heat and cool the water until the steam subsides (usually about 5 minutes).
If you dip the pretzels while the lye is very hot, you will get a darker brown color on the final product. If you dip after it is more lukewarm (or, if you make the solution with lukewarm water instead of heating it) you will get a caramel color instead.