Hope the following might help:
- When you have your icing to the correct consistency, squeeze it through some muslin.
- Or if you don’t have any muslin, then try squeezing the icing through one (parchment) piping bag into another, making sure the first piping bag only has a very small hole (no need for a tube/tip in the first one).
- Failing that, you can try ‘flattening’ out any bubbles or sugar grains with a palette knife on a board – keep flattening it down, scraping up the sides regularly, so none of it has a chance to dry out. This last method is the method taught to me on a course by Peggy Porschen.
- If all the above fail, then soak the PME tube/tip in boiling water for just a few minutes. Use a new (or one used specifically for food) paint-brush to clean out the tip. Even the slightest bit of dried icing sugar will affect the flow of icing.
- Lastly (sorry, I do go on a bit) make sure that in-between piping, you don’t let the piping bag sit – push the tip gently into a barely damp cloth (not wet otherwise it will make the icing in the tip runny).