Baking · Oct 2026
Icing Sugar Guide: How to Make Smooth Buttercream, Royal Icing and Glaze
A simple guide to icing sugar: what it is, how to use it for buttercream, royal icing, glaze and fondant, and how to keep it lump-free.
Sift the icing sugar first, then add liquid a little at a time for smooth buttercream. Illustrative image, made with AI.
The short answer
Icing sugar is sugar ground to a very fine powder, so it melts into buttercream, royal icing, glazes and fondant without any grainy bite. Sift it first, add liquid a little at a time, and keep the pack closed in a cool, dry place so it stays lump-free.
What is icing sugar?
Icing sugar is ordinary sugar milled into a soft, fine powder. In some countries it is called powdered sugar or confectioners' sugar. Because the grains are so small, it dissolves almost instantly, which is why bakers reach for it whenever a topping, frosting or glaze has to be perfectly smooth.
Some icing sugars include a small amount of starch to help stop clumping, so check the pack if you need to know exactly what is in it. Kenafric describes its own Icing Sugar as an extra-fine powdered sugar that dissolves into buttercream, royal icing and fondant without graininess or lumps.
Why not just use ordinary sugar?
Ordinary (granulated) sugar is made of crystals, and in a cold mixture such as buttercream those crystals do not fully dissolve. You end up with a gritty frosting. The fine powder of icing sugar blends in smoothly, so the texture stays silky. That is the whole reason it exists.
How to make smooth buttercream
- Beat soft butter until it is pale and creamy.
- Sift the icing sugar, then add it a little at a time, beating well after each addition.
- Loosen it with a splash of milk or cream, one teaspoon at a time, because it thins quickly.
- Taste it. If it is too soft, beat in more sifted icing sugar. If it is too stiff, add a little more milk.
A common starting point is about twice as much icing sugar as butter by weight. Then adjust to taste and to the weather: warm kitchens make buttercream softer, so chill it briefly if it slips on the cake.
Royal icing for piping and decorating
Royal icing is icing sugar beaten with egg white or meringue powder and a few drops of lemon juice. Beat it until it holds stiff peaks for piping fine details, or loosen it with a few drops of water to flood the top of biscuits. It dries hard, so keep the bowl covered with a damp cloth while you work. If you would rather not use raw egg white, meringue powder is the usual alternative.
A quick glaze
For a shiny glaze, stir a few drops of water, milk or lemon juice into icing sugar until it is thick but still pourable. Drizzle it over cakes, buns or doughnuts while they are still slightly warm. Add the liquid very slowly: a few extra drops turn a glaze from glossy to runny.
Fondant and dusting
Icing sugar is also the base of rolled fondant, the smooth icing used to cover celebration cakes, and it is often used to dust the work surface so the fondant does not stick. Many bakers buy fondant ready-made. For a simple finish, a light dusting of icing sugar over pastries and desserts looks elegant and takes seconds.
How to keep icing sugar lump-free
- Sift it. A fine sieve removes small lumps before they reach your mixture.
- Keep it dry. Moisture is what makes icing sugar clump, so close the pack after every use.
- Store it cool. Kenafric's storage advice is to keep it in a cool, dry place to prevent clumping.
Choosing a pack size
Kenafric Icing Sugar is listed in three sizes: 500g for retail, 5kg for bakeries and 15kg for bulk and commercial kitchens. A 500g pack suits the home baker. The larger packs suit bakeries and caterers who use it every day.
Source: Kenafric Icing Sugar product page, kenafricind.com, read 1 October 2026.
Key takeaways
- Icing sugar is very finely powdered sugar, so it dissolves into buttercream, royal icing, glaze and fondant without graininess.
- Always sift it, and add liquid a little at a time.
- For buttercream, about twice as much icing sugar as butter by weight is a common starting point. Adjust to taste.
- Moisture causes lumps, so keep the pack closed and store it somewhere cool and dry.
- Kenafric Icing Sugar comes in 500g, 5kg and 15kg packs.
Questions people ask about icing sugar
Why is my buttercream grainy?
Usually the icing sugar was not sifted, or ordinary granulated sugar was used instead. Use icing sugar, sift it, and beat well. A teaspoon of milk can also help any remaining sugar dissolve.
Can I make icing sugar at home?
You can blitz granulated sugar in a high-speed blender until it becomes a powder, then sift it. The result is usually coarser than shop-bought extra-fine icing sugar, so it can leave a slight grit in very smooth frostings.
What is the difference between icing sugar and caster sugar?
Caster sugar is finely ground but still made of small crystals, which suits cake batters and meringues. Icing sugar is milled to a powder, which suits frostings, icings and glazes.
How do I stop icing sugar from clumping?
Keep it away from moisture. Close the pack tightly after each use, store it in a cool, dry place, and sift it before you use it.
What sizes does Kenafric Icing Sugar come in?
500g for retail, 5kg for bakeries and 15kg for bulk and commercial use.
What is icing sugar used for?
Buttercream, royal icing, glazes and fondant, and for dusting pastries and desserts.
See Kenafric Icing Sugar
Extra-fine, bakery-grade icing sugar for home bakers and commercial kitchens.
View the product