How to tell if your jam or jelly is set Always making runny fruit sauce instead of jam or jelly? These tips from The Canadian Living Test Kitchen will help you jar a solid batch of preserves. By The Canadian Living Test Kitchen Gel stage test Chill 2 or 3 small plates in freezer. Remove jam from heat while doing test. Place 1 tsp (5 mL) hot jelly or jam on plate and freeze for 1 minute. Remove from freezer. Surface should wrinkle when edge is pushed with finer, as seen in image at left. If not, continue cooking your jam or jelly and repeat test every few minutes. How full should my jar be? The space between the top of the food and the top of the jar is called headspace. Using a gauge - seen in the image at left - takes out any guesswork. • Pickles, fruit, relishes, chutneys and condiments require 1/2-inch (1 cm) headspace. • Soft spreads (jams, jellies, conserves and marmalades) require 1/4-inch (5 mm) headspace. This article is part of our best-ever online guide to home preserving. Find recipes for jams, jellies, relishes, salsas, chutneys, pickles, marmalades and more.