The directions for my tomato sauce are as follows:
About 40-60 tomatoes
1 Tbs. lemon juice per pint jar
1/2 tsp. canning salt per pint jar
To blanch clean tomatoes, put in a pot of boiling water for 1 minute and immediately place in ice water bowl for 1 minute to cool. Remove skin and place in blender, blend into a liquid and strain as your pouring it into a large pot. Once pot is 3/4 th full,(it will boil over if you overfill) turn stove on med-high heat uncovered stirring occasionally till it comes to a rolling boil, then decrease to med. heat. After about 1 hour the froth will disappear. At this stage it is tomato juice. Cook for approx. 1/2 hour longer to make tomato sauce, if cooked longer you will get tomato paste. In the water bath canner your jars should have been boiling approx. 20 minutes, lids have been in very hot but not boiling water. Get jars out of canner and set on towel on counter and place canning salt and lemon juice in each jar, then funnel in tomato sauce leaving 1/4 th inch head space. Wipe top of jars with a damp cloth and put on lid. Place ring on only hand tight so air can escape during processing. Process for 30 minutes, start timing after it has come to a rolling boil. Let stand in canner for 15 minutes, remove and place on towel on counter, careful not to turn jar over. Should hear the lid "Pop" sound when it is sealed. Let sit in the counter untouched for 24 hours. Label and date each jar.
As a side note: Roma tomatoes are meatier, other tomatoes that are juicier may require more cooking time to turn into sauce, it's usually done when the pot is 1/2 the amount of liquid that you started with.