If using the screw-top jars, such as the Mason, screw down with the thumb and little finger, not using force but stopping when the cover catches.
If using vacuum-seal jars put the cover on and the spring in place. The spring will give enough to allow the steam to escape.
In using glass-top jars with the patent wire snap, put the cover in place, the wire over the top and leave the clamp up.
The cover on a glass jar must not be tight while the product is cooking, because the air will expand when heated, and if the cover is not loose enough to allow the steam to escape the pressure may blow the rubber out or break the jar.
The product is now ready for the canner.
STERILIZING
If you are using the homemade outfit, such as wash-boiler or garbage pail, all berries and soft fruits are sterilized sixteen minutes; in all commercial hot-water-bath outfits and in condensed steam, sixteen minutes; in the water-seal, twelve minutes; in the steam pressure under five pounds of steam, ten minutes; and in the pressure cooker under ten pounds of steam, five minutes. Do not allow the pressure to run above ten pounds for soft fruits; fifteen pounds makes them mushy.
If you use any type of hot-water-bath outfit be sure the water is boiling when the fruit is lowered into the canner, and keep it boiling vigorously for the entire sixteen minutes. At the end of the sterilizing time, immediately remove the jars from the canner.
In taking canned goods from boiling water care is needed to see that they are protected from drafts. If necessary close the windows and doors while lifting the jars out, as a sudden draft might break them.
Examine rubbers to see that they are in place. Sometimes if a cover is screwed down too tight the pressure of the steam from the inside causes the rubber to bulge out. Simply loosen the cover a thread or two, push the rubber back into place and then tighten.