Clear Jel is a modified cornstarch that is used as a thickener for canning, especially for pie fillings, because it can withstand the heat of canning and doesnt lose its thickening power after extended heating. It is chemically modified to create bonds between the water molecules and the starch molecules, which continue to expand as they are heated, thickening the mixture. Clear Jel is recommended for canning because it is more effective than regular cornstarch, which starts to break down at high heat and doesn't thicken high-acid liquids well. Clear Jel is used just like flour or cornstarch, and produces excellent sauce consistency even after fillings are canned and baked.