“ Certo jelly recipes are developed with fully ripe fruit instead of the under-ripe fruit commonly used in old-fashioned jelly making. They take you a long way toward perfect flavor. And Certo jelly recipes are designed to give best texture at the time the jelly is most apt to be used. They take account of the fact that many jellies grow progressively firmer for a week to a month after they are made. ”

“ The kettle or saucepan should be less than one-half full of sugar and fruit to permit a full rolling boil, a boil which cannot be stirred down. Use hottest flame. If fire is slow, keep kettle covered after sugar is dissolved until mixture comes to a boil. Stir while coming to a boil, and while boiling.
5. Add Certo: For jelly, add Certo as soon as fruit juice and sugar mixture comes to a boil; then bring to a full rolling boil and boil hard for exactly 1⁄2 minute, stirring constantly. For jam, cook fruit and sugar mixture at full rolling boil for exactly 1 minute, stirring constantly ”

“ Prepare Fruit: Select fully ripe fruit. Wash, then prepare exactly as recipe directs. If fruit lacks tartness add 1⁄4 cup lemon juice when adding sugar. For separating juice for jelly, use 1-yard square of Canton flannel, spread over colander. Place prepared fruit in cloth, bring corners together and twist while pressing down on bag. To make jellies from dripped juice, use twice amount of fruit called for in recipe.
2. Prepare Glasses: Wash, scald, and drain the glasses and tin covers needed, and melt paraffin in a small pot over hot water while making jelly or jam. ”