SAN JOSE -- The emergency room at Valley Medical Center was closed for about an hour Friday morning after a mysterious residue on a patient's clothes prompted a visit from a hazardous materials crew, which found nothing harmful, authorities said.

A man was taken to the hospital around 4:45 a.m. after he claimed that he had been sprayed with an unknown chemical substance. The emergency room staff realized only after he entered that he had not been decontaminated and put him in an isolation room where they applied warm water and soap, hospital spokeswoman Joy Alexiou said.

Out of an "overabundance of caution," a hazmat team from the San Jose Fire Department was summoned at 7:30 a.m. to examine the man's clothing and areas with which he came into contact, Alexiou said.

While the facility was swept, the emergency room was closed to ambulances and patients.

Fire Capt. Cleo Doss said thorough tests turned up no trace of any harmful substance.

"We used every type of meter and testing we have," Doss said.

Doss said the substance could have been something similar to spray paint or a component of the patient's clothes that had broken down. Either way, whatever it was had dissipated, Alexiou said.

No one reported any ill effects during the period in which the unknown substance was thought to have been exposed, Alexiou said. The patient is listed in fair condition.

Contact Robert Salonga at 408-920-5002. Follow him at Twitter.com/robertsalonga.