When you need to adhere a piece of metal leaf to a surface, you might wonder how to make it stick. That is where gilding sizes come into play. There are many varieties available, and you can even find DIY recipes to make your own. If you are wondering how to start gilding the size, this quick guide is going to explain everything you need to know.
Let’s get started.
What Are Gilding Sizes?
You might think that gilding sizes are the measurements of something, but gilding with size actually means using an adhesive. Typically, the object or surface where the gild is being applied is either nonporous or not undulated, which is why you need to stick the gild on with size. Gilding sizes come in three types: water-based, alcohol-based, and oil-based. Most people find that oil-based sizes are preferable to those made with water or a solvent, but all have their applications.
Differences in Oil, Water, and Alcohol-Based Gilding Sizes
Before diving into gilding sizes and using them, it is imperative that you know when to use oil-based and water-based sizes. Most of the time, a water-based size is used when using surfaces that have medium porosity. Think paper, plaster, and wood. Water-based size is historically made from a mix of gelatin, looks cloudy in the can, and dries clear.
Alcohol-based is ideal when you have smooth, solid surfaces, including plastic, gold, silver, and glass. For gilded items that will return indoors and away from weather, alcohol-based gilding sizes are a good choice. Lastly, oil-based gilding sizes are commonly used for outdoor objects but can be used for any oil gilding project. You can choose oil-based sizes for both smooth, compact surfaces (glass or metal) or more porous surfaces (like stone or wood).
How to Use Oil-Based Gilding Sizes
Prior to using an oil-based gilding size, it is important to clean the surface. You can also apply a coat of varnish to protect the surface from corrosion or oxidation. This also makes the surface homogenous. If working with stone, use a sealant or coating that will insulate the stone and keep it from absorbing moisture.
Applying Oil-Based Gilding Sizes
You will need:
- Oil-based size, 3 or 12 hours
- Marten hair brush, flat or round (round and small if doing an inlay)
Note: An hour size is based on how long it takes to begin gilding after the size has been applied. Therefore, a 3-hour size means that you can gild the surface 3 hours after applying the adhesive.
When applying the size, spread as thinly and evenly as possible. Avoid streaking or lumping the size on the surface.
Drying Oil-Based Sizes
After applying the size, it is important to wait for the amount of time written on the tin (either 3 or 12 hours). When evaluating whether the oil-based size is dry, touch it with the back of your hand. It should be sticky but not wet. Do not wait too long. Otherwise, the size will dry completely, which means that the metal leaf will not adhere. If you apply the leaf to the size too quickly, it will make the metal leaf lose its shine.
How to Use Water-Based Gilding Sizes
You will need the following tools when preparing the surface for your size:
- De-waxed shellac or paint to reduce absorption of gilding size
- Sandpaper for smoothing the surface
- Acrylic color – optional, for adding background color
Although water-based gilding size is ideal for porous surfaces, it must not be too porous. If that happens to be the case, you need de-waxed shellac (or any paint) to remove some porosity. Smooth down the surface of whatever is to be gilded. If you wish to warm the size, apply yellow or red paint for gold leaf (black or gray for a genuine silver leaf), then sand down the acrylic paint before applying the gilding size to the gold or silver.
Applying Water-Based Size
Once preparations are complete, you will need:
- Water-based size
- A soft hair brush of good quality
Using the brush, evenly apply the water-based size. Each layer of size should be thin and smooth. The less porous the surface, the less size is needed to make the leaf adhere. Avoid putting on too thick a coat, as that could result in wrinkling, cracking, and bubbles in the leaf.
Drying Water-Based Size
The rate at which water-based size dries depends on how much you applied. Touch the size with the back of your hand. You want the size to be only slightly sticky. Nothing should come off on the back of your hand. Do not touch with your fingertips, as this could leave prints in the size that affect the surface of the gilding.
Water-based sizes tend to take between 10-45 minutes to dry.
How to Use Alcohol-Based Gilding Sizes
Similar to working with a water-based gilding size, you will want to make the surface you are working with as smooth and homogeneous as possible. Use some suitable primer and optional acrylic paint.
Apply Alcohol-Based Gilding Sizes
Working with an alcohol-based size is much like using a water-based size. You will need a material like a brush with soft hair or a pad to smooth the size over the surface. Optionally, you can use a spray gun. Like water-based size, spread the size as thinly as you can. If the layer is too thick, it will result in imperfections on the surface and could destabilize the leaf, resulting in cracks and other cosmetic issues.
Drying an Alcohol-Based Size
Follow the same directions as with a water-based gilding size. Touch the back of your hand to the size to make sure it is sticky. Generally, alcohol-based gilding sizes take between 30-60 minutes to dry, unless you are working with a more porous surface.
Time to Size Up Your Leaf
Upon following these instructions for gilding with size, you know what comes next: leaf application. There are different gilding sizes, so use the tips in this article to help you choose the one that is right for your project. With any kind of gilding size, you only need a little bit for beautiful results.
You should use either water-based or oil-based gilding sizes. If the wood is going to be indoors, water-based is the better option.