For Consistency

• Piping icing should be thick enough to hold its shape when it lands on the cookie, similar to outlining icing. This thicker royal icing is perfect for the final decorations that sit on top of a cookie and make it so much fun. 
• You might notice that the humidity in the room affects the consistency of the icing. Your recipe should be adjusted accordingly. It might be tricky at first, but don’t get discouraged! Once you get the hang of it, you’ll even develop your own preferences for thicker or thinner icing.
• For example, you’ll probably want thicker icing for outlining. For flooding (filling in the entire cookie), you’ll want your icing on the thinner side. This allows it to blend in seamlessly on top of your cookie—it looks so nice and professional!

For Coloring

• Personally, I recommend dividing your icing into several “work bowls” so you can color them individually. Work with one container at a time, keeping the others tightly covered with plastic wrap so they don’t dry out.
• Using a toothpick, add food coloring a little at a time, mixing well after each addition. I love using gel food coloring as opposed to liquid coloring—you’ll get more vibrant colors and it’s easier to control the consistency. Remember to mix it really well, or you might see streaks of color on top of your cookies later.

For Decorating - Bordering

• Icing at this consistency is used to outline the edge of a cookie. The outline creates a border or dam so that the rest of the cookie can be easily flooded (filled) with a thinner icing. This step keeps the flooding icing from flowing over the edge of the cookie and making a big mess!
• Outlining-consistency icing should squeeze easily out of a #2 pastry tip, stay in place, and hold its shape on the cookie when it lands. If the icing is too stiff, it will be hard to squeeze. If it is too loose, it will spread a little when it lands on the cookie—this won’t help when you start flooding. 
• Try to pipe around the shape of the cookie in one unbroken line. Get the icing as close to the edge as possible without it falling off. When the end of your outline meets the spot where you started, lift the bag to end your line. Make sure the ends meet and the outline is closed!
• You can use a spray bottle filled with water to fine-tune your icing consistency. With your icing in a bowl, spray water a little at a time, mixing thoroughly after each addition, until you get the consistency you are looking for. The icing needs to flow smoothly through a tube and curve without breakage, but it should still be stiff enough to hold its shape. 
• Test the icing before you put it on a cookie! Put a little bit of icing into a pastry tip and push it through with your thumb. Make a few practice loops on some waxed paper. The loops should stay intact, not run together.

For Decorating - Flooding

• After a cookie is outlined, a thinner version of the same icing is used to fill in the outlined area. The icing should flow until it fills the entire cookie. When you squeeze the icing on the cookie, it should immediately flow toward the piped borders. If it is too thin, coverage will be too transparent and you’ll need a thicker consistency.
• Remember that each flooded cookie should be completely dry before you start to decorate with piping icing. If it’s not dry, your piped decorations will bleed into the thinner icing.
• Squeeze the flood icing from a pastry bag or squeeze bottle into the middle of the shape. It should flow toward the outline dam. Use a small offset spatula or a toothpick to coax the icing into the corners and edges of the shape. If you see any air bubbles on the surface of the cookie, use the tip of a toothpick to puncture them.
• Fill in the gaps! I like to pipe my flooding icing about ¼-inch in from the edge of the cookie. While I flood my cookies, I hold my scribe tool (you can find plenty of options on Amazon) or a toothpick like a pencil. Using a swirling motion, I push the icing toward the edge of the cookie, filling in any gaps along the way. Continue pushing the icing out until you have about 1/8-inch of space all the way around the edge of the cookies. Keep in mind that the icing will start to crust over within about 5 minutes so work quickly. Tap the cookie on the table a few times to smooth out any bubbles or bumps and move the flooded icing to the edge.

For Decorating - Finishing

• Now it’s time to decorate with colorful sugars, candy, and nuts! These all stick readily to wet, flooded icing. Sanding sugar can be sprinkled directly onto the wet icing, too. I recommend using tweezers to place dragées and nonpareils precisely on the cookie. You can still attach decorations after the flood icing has dried—just use a dab of the same color icing to affix the decoration.
• Add your sprinkles, sanding sugar, and nonpareils BEFORE your royal icing dries!You can add finishing touches after the icing dries on your first coat.

For Storing

• Dry and store your decorated cookies. After flooding, cookies need to dry for about 4 hours and a full 24 hours before storing. Do not cover the cookies while they are drying. Once they are completely dried, I like to place each cookie in a zip-lock bag and then store them in an airtight container.