How to execute oil-based size gilding | Giusto Manetti Battiloro

Oil-based size gilding with pure gold or silver leaf
Stages and tools for the application of the oil-based size

This oil-based size is used when gilding compact surfaces (such as metal, marble and glass) which will be placed indoors or outdoors. It is particularly suitable for:

• Domes
• Sculptures
• Metal items placed outdoors
• Metal items placed indoors
• Marble and stone items
• Wood items placed outdoors

Use oil-based size to apply both pure gold and silver, loose or transfer leaf. In the latter case, using a sheet of tissue paper will facilitate grip and application, speeding up and simplifying the gilding process.

Transfer leaf is the most suitable format when gilding for the outdoors. Air currents and sudden gusts of wind could damage loose leaf when the booklet is opened.

For imitation leaf gilding you will find more information here.

Base material preparation

Tools:

• Products suitable for the treatment and protection of the base material
• Acrylic colour (optional) to add colour to the background

When you are gilding metal elements it is a good idea to clean the surface well and then apply a protective coat before applying the varnish (optional) and subsequently applying the size. This step serves to remove traces of oxidation/corrosion of the surface and to prevent reappearance in the future.

On very smooth base it is also useful to apply a clinging primer that will prevent the size from thickening on one part of the surface.

When working on marble or stone, we recommend a preventative coat that has special insulating products that will prevent the stone from absorbing water or moisture over time.

If you would like the gilding to have a warmer and more even colour, you can also apply an acrylic colour to the base (usually yellow or red for gold, and black or grey for silver).

Application of the oil-based size

Tools:

• Brush made of marten hair, round or flat
• Oil-based size, 3 or 12 hours

We recommend brushing on the size with a marten hair brush, preferably flat for flat surfaces or round (and small) for inlays.

During the application it is very important to spread the size as evenly as possible, in order to avoid the formation of lumps or streaks.

The oil-based size requires much longer drying times than the water or alcohol bases. For this reason it is equally important to limit the thickness as much as possible in order to avoid imperfect drying, which would make the primer unstable.

Oil-based size drying

Before you can apply the leaf on the size you must wait from 3 to 12 hours, depending on the type of product you are using. In order to evaluate the right drying time, we recommend touching the area with the back of your hand. It must be slightly sticky, but must not leave a damp residue on the skin nor detach from the base material. We do not recommend touching the surface with your fingers, in order to avoid leaving prints on the size, which would remain visible even after you’ve gilded the surface.

It is important to be very careful when evaluating the waiting time before applying the leaf. If you wait too long there is a risk of it drying completely, which would not allow the leaf to adhere. If you don’t wait long enough, interrupting the drying process of the size will make the gilding unstable and cause the leaf to lose its shine. Humidity and room temperature are two other factors that significantly affect drying time, especially in outdoor settings. A space that is humid or too cold (even if it is dry) will tend to lengthen the drying time and hinder the drying process.

Leaf application

Tools:

• Loose or transfer gold or silver leaf
• Gilding cushion
• Gilding knife
• Squirrel hair gilder’s tip
• Cotton pad or Kolner cloth

To apply the gold or silver loose leaf, gently open the booklet and place it up against the gilding cushion. With the help of a gilding knife, slide the leaf onto the cushion and apply it by lightly blowing on it. It is essential that the leaf never comes into contact with your fingers to avoid damaging it and making it unusable.

With the gilding knife you can also cut the leaf into smaller parts. This will make it easier to grip and apply to the surface you are gilding by using a squirrel hair gilder’s tip. The size of the gilding tip depends on the size of the leaf.

Transfer leaf is recommended for gilding flat surfaces, for outdoor gilding and when you do not need to cut the leaf. To apply, simply remove the leaf from the booklet, lay it facing downwards and flat on the surface you are gilding, apply light pressure all over the tissue paper, using padding (like a cotton ball) and remove the tissue paper, which will detach smoothly without clinging to any metal parts.

Protective coat

Tools:

• Soft hair brush
• De-waxed shellac or synthetic protection
• Acrylic paint for outdoor use

Once the leaf has been applied, a finishing varnish can be added to the decorated surface which will help to preserve it from damage. The protection 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.

It is always advisable to apply a protective coat with acrylic paint (and not with wax) on gilded items that will be outdoors, in order to protect them from damage caused by weather and temperature changes and to ensure a longer life.

When gilding pieces that will be place indoors, we recommend applying one or two coats of natural de-waxed shellac, using a soft bristle brush. 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 remember that it will in any case change the appearance of the leaf in terms of colour tone and glossiness.

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