Michigan State University Extension
Preserving Food Safely - 01600949


     Follow these steps for successful pressure canning:    

     1.  Put 2 to 3 inches of hot water in the canner.      
         Place filled jars on the rack, using a jar         
         lifter.  Fasten canner lid securely.               
     2.  Leave weight off vent port or open petcock.  Heat  
         at the highest setting until steam flows from the  
         petcock or vent port.                              
     3.  Maintain high heat setting, exhaust steam 10       
         minutes, and then place weight on vent port or     
         close petcock.  The canner will pressurize during  
         the next 3 to 5 minutes.                           
     4.  Start timing the process when the pressure reading 
         on the dial gauge indicates that the recommended   
         pressure has been reached, or when the weighted    
         gauge begins to jiggle or rock.                    
     5.  Regulate heat under the canner to maintain a       
         steady pressure at or slightly above the correct   
         gauge pressure.  Quick and large pressure          
         variations during processing may cause unnecessary 
         liquid losses from jars.  Weighted gauges on Mirro 
         canners should jiggle about 2 or 3 times per       
         minute.  On Presto canners, they should rock       
         slowly throughout the process.                     
     6.  When the timed process is completed, turn off the  
         heat, remove the canner from heat if possible, and 
         let the canner depressurize.  DO NOT FORCE-COOL    
         THE CANNER.  If you cool it with cold running      
         water in a sink, or open the vent port before the  
         canner depressurizes by itself, liquid will spurt  
         from jars, causing low liquid levels and jar seal  
         failures.  Force-cooling may also warp the canner  
         lid of older model canners, causing steam leaks.   
         Depressurization of older models should be timed.  
         Standard size heavy-walled canners require about   
         30 minutes when loaded with pints and 45 minutes   
         with quarts.  Newer thin-walled canners cool more  
         rapidly and are equipped with vent locks. These    
         canners are depressurized when their vent lock     
         piston drops to a normal position.                 
     7.  After the vent port or petcock has been open for 2 
         minutes, unfasten the lid and remove it            
         carefully.  Lift the lid away from you so that the 
         steam does not burn your face.                     
     8.  Remove jars with a lifter, and place on towel or   
         cooling rack, if desired.                          

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