USING A PIPING BAG
Disposable piping bags are ideal because they pose no hygiene problems. You can use a piping bag without a piping nozzle to fill a tart case cleanly, pass from one dessert piece to another or pipe fine lines with icing. Cut the end of the bag to the desired size, fill it, then pinch the end between your thumb and index finger to control the flow.
There are several types of nozzle (plastic or stainless steel) for decorating and filling neatly: Mont Blanc or grass nozzle, St Honoré tip (slit on one side) and so on. The shapes obtained depend on how the bag is held, upright or on a slope. The nozzles are named according to the diameter of their opening in millimetres: a no. 10 nozzle has a 10 mm opening.
Pipe onto a metal baking tray lined with baking paper, directly onto a nonstick metal baking tray or onto a silicone mat – except for choux pastry.
To obtain evenness with piping, use a template. Trace circles in staggered rows on a large piece of paper using a drinking glass or a biscuit cutter. Place the template on the baking tray and cover it with a sheet of baking paper (that way you can reuse the template, but you could also trace the circles directly onto baking paper, then turn it over before piping). To keep the paper on the tray, put some weights (a knife or a glass) on it then gradually move them as you pipe.
Put the chosen nozzle in the bag. Mark or nick the end of the bag where the nozzle sits correctly. Lift the nozzle and cut along the mark. Put the nozzle in place, twist the bag just above it and push the twisted part into the bottom of the nozzle so the mixture doesn’t run out before you start piping. Fold the top of the bag back over your hand. Use a silicone spatula to put the mixture in the bag, scraping the spatula against the hand holding the bag. Fill to two-thirds maximum to avoid the bag overflowing. Pull the top of the bag back up and give it a quarter turn while pushing the mixture towards the tip. Pull on the nozzle to remove the ‘cork’ and turn the bag to make the mixture move down.