During most cotton production seasons enclosed storage facilities will not hold all the cottonseed and cottonseed hulls and therefore it is necessary to store some of thes these materials outside in unprotected piles. Although these cottonseed and hull piles can be covered with tarps, it is expensive and time consuming. A simpler and inexpensive method of covering these products is needed. Hydro-Tect has been sprayed on hay bales, grain sorghum, and cotton modules to protect these materials from the environment while stored outside. Hydro-Tect is a water soluble material formulated from psyllium seed husk and carboxmethyl cellose gum(CMC). Previous studies have found the material to be somewhat effective on seedcotton stored in modules. The material protected some of the module but the uneven top surface of the module did not allow adequate coverage and, therefore, there were areas where the water penetrated the module and the cottonseed became excessively wet and the seed and lint deteriorated. From these studies it was felt that the high angle of repose for cottonseed, 45 , would make this material more feasible for this type of cover. Tests were conducted at 3 locations, Casa Grande Cotton Oil Mills in Lamesa, TX and Casa Grande, AZ and Anderson-Clayton Oil Mill in Phoenix, AZ. Only cottonseed was tested at Lamesa while cottonseed and cottonseed hulls were teste at both locations in Arizona. The size of the cottonseed pile at Lamesa was such that only a 20 ft band was sprayed at the bottom, on two sides and one end of the pile. The untreated areas at the bottom of the pile adjacent to the treated sides were used as a check. The two Arizona tests utilized seed and hull piles that were 48 ft long, 10 ft high and 20 ft wide, which included approximately 43 tons of seed and 20 tons of hulls. The piles were sprayed with a spray boom mounted on a pickup. The boom consisted of 1½ in dia pvc pipe manifold equipped with number 15 wide angle flat spray nozzles mounted on 20 inch centers. Alternate nozzles were offset 2 inches to prevent the spray patterns from adjacent nozzles hitting and distorting the coverage area. The spray boom was operated at 40 psi with an output of 3 gpm per nozzle. This modification of the spray boom provided more even spray coverage due to improved pressure and spray volume at the nozzles. The Lamesa site was treated on March 23, 1995 and the last seed samples were collected on September 6, 1995 while the Arizona sites were treated on March 28, 1995 and last sampled on August 20, 1995. Each site was also sampled during July, 1995. The limiting factor for a successful test at all 3 sites was lack of rainfall. Casa Grande, AZ, Phoenix, AZ, and Lamesa, TX received 1.5 in, 2.5 in, and 6.3 in of rainfall, respectively. Lamesa, TX was the only site that received adequate rainfall to determine the effectiveness of the treatment. No differences were noted in cottonseed moisture or cottonseed hull moisture at Phoenix, AZ or Casa Grande, AZ. The cottonseed moisture at Lamesa, TX went in at 5.1 moisture and was removed at 5.8% moisture content for the untreated area while the final moisture content in the treated area was 5.2%. Other advantages of treating cottonseed hull piles were noted at the Phoenix, Az site. Blowing cottonseed hull dust was greatly reduced for the treated hull pile. A storm at the same location resulted in the untreated hull pile being severely damaged while no significant damage was noted for the treated pile.