A mysterious substance that halted surgeries at the Minneapolis Veterans Medical Center on Wednesday has been identified as “residual cleaning fluid” that posed no threat to patients.

The Minneapolis VA will resume surgeries Friday.

“The safety of our patients is always our number one priority,” the VA Health Care System said in a statement.

An evaluation of the material found in the hospital’s main sterilizers showed it to be residue of a cleaning product that had not been fully rinsed.

The sterilizers have been inspected and certified as ready for use by the manufacturer, the medical center said Thursday. It said it’s reviewing its processes to ensure a full rinse of cleaning products is accomplished according to manufacturer standards.

Dozens of surgeries were postponed or rescheduled on Wednesday after the substance was discovered by staff.

Mark Brunswick