Wash and scrub 4 of the lemons thoroughly. Cut them lengthwise into quarters from the tip to within 1/2 inch of the stem end, so the quarters stay together at one end. (If you don't have a widemouthed jar, go ahead and separate the quarters.) Juice the remaining 2 lemons.

Put the cut-up lemons in a large bowl with the salt and toss to coat, packing the salt into the cut edges of the lemon. Re-form them into lemon shape, and pack them tightly into the sterilized jar with any extra salt and the cinnamon, cloves, and bay leaf. Pour in the lemon juice and cover the jar. Store in a cool place for 1 week, tipping the jar once a day to mix in the salt. After a week, put the jar in the refrigerator and keep for 3 more weeks before using. Rinse preserved lemons before using to remove excess salt.