Harvest seaweed from a site that you trust for cleanliness. Steer clear of locations that are known to be contaminated with human waste or chemicals.
Wash the seaweed, taking particular care to remove visible debris. Washing with detergent is unnecessary; simply rinsing under plain running water with slight agitation will be sufficient to loosen impurities.
Dehydrate at a high enough temperature to evaporate water quickly to avoid mold growth, but low enough temperature to avoid the seaweed being "cooked" instead of dried. Seaweed should dry in six to 16 hours, and should be leathery when done. If using an electric dehydrator, set it on the same setting that you use for other vegetables. If using a solar dehydrator, temperature and humidity are going to be important to your ability to dehydrate. Typically you need three to four days of temperatures higher than 100 degrees F to dehydrate successfully, and very low humidity. This is also true when using a drying rack, with the added need for adequate ventilation for the seaweed on all sides, in order to dehydrate evenly and completely.
Read more: How to Dry Seaweed | eHow.co.uk http://ping.fm/teYbG