Incorrect Ingredient Measurements

• When you're making candy, proportions are important; never change the proportions in your fudge recipe and always follow ingredient measurements exactly. Don’t double the recipe, because doing so can alter the cooking time and temperature -- and lead to improper crystallization. Don’t substitute a main ingredient, such as using margarine instead of butter, or sugar alternatives instead of granulated white sugar. It's okay to substitute add-ins, such as nuts or fruits.

Crystallization Problem

• Cooling fudge too quickly -- such as placing the pot in the refrigerator -- can cause premature crystallization, which leads to a grainy, separated fudge with a dull appearance. Always cool your fudge syrup at room temperature. When fudge is lukewarm, it promotes crystallization equally. While the fudge syrup is cooling, don’t stir or disturb it, because this can cause the crystals to form all at once, which also can cause a separated, grainy fudge.

Temperature Issues

• Cooking your fudge to a temperature greater than 240 degrees Fahrenheit can result in a crumbled fudge. Use a candy thermometer to monitor the temperature of your fudge syrup. Once it reaches 238 degrees Fahrenheit, remove it from the stove, and pour it into a separate bowl to cool until it cools to 110 to 115 F.

Kneading Issues

• Fudge disturbed before it cools to the 110 to 115 F point can separate and become grainy. Check the temperature of your fudge before you knead it. Once it is at the right temperature, knead it until the shine on the fudge disappears. This prevents premature crystallization and keeps your fudge smooth.

Ignoring Critical Instructions

• Ignoring any of the directions in fudge-making can result in a separated product. Cautions listed in your recipe, such as washing down the sides of the pan with a moist pastry brush or covering your pan early in the cooking process, can result in a grainy, coarse texture. Follow the instructions in your recipe, paying particular attention to all the precautions.

Bad Candy-Making Weather

• Cooking fudge on a humid, hot day can cause the formation of unwanted crystals, resulting in a grainy, separated product. Cool weather is ideal because your fudge syrup will cool quickly at room temperature and not go through premature crystallization. Also, because candy relies on a ratio of moisture to sugar, cooking fudge on days with high humidity can impact your fudge. As fudge cools in humid weather, it can reabsorb excess moisture in the air, keeping your fudge from hardening as it's supposed to. If you can, make your fudge on dry, cool days or keep the temperature at 70 F or below, and don’t cook fudge on a rainy day.