Spray one side of plate with our highly visible penetrant—the other side with developer. If a pinhole exists, a bright colored spot will appear on the developed side. Bothproducts are water-washable and safe to use. Penetrant will cover 50 to 100 sq. ft. Approximately 2 cans of developer will be needed for every can of penetrant. Options: Also available in gallons, pails or drums for use with commercial sprayers.