Can I make the icing stiffer by adding more icing sugar? I need to make roses and the icing sugar is too soft. Will I ruin it by adding more icing sugar?

thanks!

What type of icing?

If you're using royal icing you can certainly add more sugar until you get the correct consistency

Sorry, should have mentioned that. It's Wilton class buttercream.

With buttercream, you can also add more icing sugar until you have the right consistency. In fact, you should.

Thank you!

You can also add cornstrach to thicken it up.