Using Confectioner's Varnish On Cake
Sometimes we see a cake so fragile and luminescent as to seem almost impossible to eat. Airy sugar creations leap away from the cake layers, shining as if dew has just fallen on them from the sky. This gleaming, apparently unsupported, edifice of decoration is achieved using confectioner’s varnish, which is also the ingredient that makes many top quality chocolates shine with such richness.
What Is Confectioner’s Varnish?Confectioner’s varnish, also known as pharmaceutical glaze, is derived from shellac, which is an insect product. The shellac is dissolved in denatured alcohol to create a suspension and, depending on its intended usage, can also contain food waxes and titanium dioxide which acts to make the suspension opaque. The opaque suspension is generally used to coat tablets so that they can be swallowed more easily, but it is also sometimes used in the food industry – liquorice comfits and other hard shiny sweets are often coated in a shellac glaze.
Using Confectioner’s VarnishBecause shellac is a rare 'approved' food ingredient that is insoluble in stomach acid, it can be difficult for some people to assimilate, (and in the USA must be listed on cakes under Food and Drug Administration law). For this reason it’s important to understand the use (and misuse) of confectioner’s varnish and in a cake-making business, to be clear with customers where the varnish may be used, as some people may be intolerant of it, and many parents may wish to be sure of the contents of a cake for a child’s birthday, for example.
It is also recommended to take a class in using confectioner’s varnish or at least watch some online videos and read professional sugarcraft books to ensure that you fully understand the active components and best ways to use the varnish.
Working With Confectioner’s VarnishFor hobby cake-makers, small bottles of undiluted confectioner's glaze can be purchased online or from specialist decorating shops. However, the full strength version is almost never used because it is very thick, difficult to apply with a brush, and has a truly awful odour that makes the applier feel quite ill if the area is not well-ventilated. This odour disperses as soon as the varnish dries, so another reason for diluting the glaze is to speed up drying and reduce the exposure to the smell.
The usual diluting agent is alcohol in the form of isopropyl alcohol, but don’t be tempted to use the variety of isopropyl alcohol that you can buy in chemists or wholesale cleaning shops as it is not approved for food use. Specialist alcohol or ready diluted varnish can be purchased instead.
There's a real knack to using confectioner's varnish. Here are some useful tips:
Prepare in AdvanceThe key to using the varnish is to do all the preparation in advance, so that as soon as you start to paint with the glaze or dip items into it, you are able to work each item and leave it to dry. You may need several containers for the glaze, as dusts, glitters and powders, when used on sugar paste, can lift from the item and remain on the brush, so being transferred to other items that don’t have the same colour or finish.
Fix the colourThe main uses for the varnish in cake decorating are orchid petals, berries and shiny leaves such as ivy. When working with such items, you may choose to steam them, using an icing steamer, first to set any colour that you’ve applied to them. Because the varnish is sticky and inclined to clump, it is valuable to ensure the colour fixing is as strong as possible. When painting a variegated leaf or petal, ensure you work from the lightest point of colour out to the darkest, as this stops the transfer of colour. This may mean working each item on a revolving mount or where you can walk around them, so set up the decorations before you begin to avoid having to move them around as you work.
Cover SurfacesBerries can often be dipped in a small, tall container of glaze, and then hung up to dry. This gives them a clear and brilliant finish and ensures that if there is any excess varnish, it drips off so that the berries do not look odd. Make sure you put plastic film or oilcloth below the berries as the glaze is extremely sticky and can be difficult to remove from surfaces.
If you have sugar flowers that have bloomed (lost their colour or crystallised on the surface owing to damp) you can sand them gently, dry them, and restore their surface by painting them with glaze.
Alternatives to Confectioner’s VarnishSome manufacturer’s use zein, a corn protein, especially in vegetarian foods, but this is not yet commonplace in small-scale production or hobby cake-making.
A home-made alternative is 50% corn syrup – obtainable from cake decorator supply shops in the UK and widely sold in the USA - mixed with 50% high quality vodka. It will stay tacky much longer than confectioner’s varnish (up to three days) and can be inclined to break down in very hot or very moist conditions.