How to execute water-based size gilding

Tools:

• De-waxed shellac (or other paint) to reduce size absorption
• Sandpaper for smoothing
• Acrylic colour (optional) to add colour to the background

In order to ensure good adhesion of the size and to make sure it does not absorb too rapidly, the surface where the size will go mustn’t be too porous. If it is, it is important that you apply a layer of de-waxed shellac or another paint first, which should be chosen according to the surface material.

Sand the surface with fine-grained sandpaper to make it as smooth as possible.

To make the end result of the gilding warmer and more homogeneous, you may also apply an acrylic colour on the surface (usually yellow or red for gold, and grey or black for silver) and sand the surface with fine-grained sandpaper before applying the size.

Water-based size has different drying times depending on the type you are using. Once dry you can proceed with the leaf application. To assess if the time is right, we recommend touching the area with the back of your hand. It must be slightly sticky but without leaving a damp residue on your skin and without detaching from the piece you are working on. We do not recommend touching the surface with your fingers, to avoid leaving prints on the size that would remain visible even after you’ve gilded the surface.

It is important that you be very careful when evaluating the right waiting time before applying the leaf. It normally takes 10 to 45 minutes, depending on the type of water-based size. If you wait too long there is a risk of it drying completely, which would not allow the leaf to adhere. Then again if you do not wait long enough, applying the leaf will stop the drying process of the size, resulting in unstable gilding. Humidity and room temperature are two other factors that significantly affect drying time.

Tools:

• Brush with soft hair
• De-waxed shellac or synthetic protection

Once the leaf has been applied, a finishing varnish can be applied to the decorated surface which will help to preserve it from damage. The protective coat is optional when working with high purity gold leaf. We always recommend it, however, when gilding with silver leaf or with gold leaf that has a high quantity of silver in the alloy because there is a risk of oxidation.

Apply one or two coats of de-waxed shellac natural varnish, using a soft brush, and wait for the first coat to dry completely before proceeding with the second.

So as not to alter the colour of the silver leaf, you should preferably apply an extra-clear de-waxed shellac or another transparent protective varnish.

Before proceeding with a protective coat, it is important to know that it will in any case change the appearance of the leaf in terms of colour tone and glossiness.