Research is a big part of my life as a painter. I try everything once until I find the method that suits my painting the best. Here is something I came across that I like to share with my readers:
When making images Renaissance painters were ingenious in their exploitation of their materials. To present golden objects gold leaf could be used, often in the form of mordant gilding, in which the shape or pattern to be gilded was painted with an adhesive substance, the mordant.
Gold leaf was then laid over it, adhering to the sticky mordant but not to the dry surface of the surroundings paint. Alternatively, gold leaf could be powdered and mixed with a binder to make gold paint, usually called "shell gold"because it was traditionally kept in mussel shells. In the Netherlands in the early 15th century painters began to create the illusion of metallic objects with paint alone, the lustre and reflective properties of gold indicated by highlights of lead-tin yellow. This pigment has considerable bulk when applied in oil; if details such as the gold threads in a cloth-of-gold-fabric are viewed in raking light, the relief becomes strikingly apparent. Raking light reveals the texture of oil paint and the direction of brushstrokes. A stroke made with a paint containing dense lead-based pigments may form ridges of impasto. Brushes can be used to manipulate the colours while they are still soft so that they bleed into one another or displace the paint of previous strokes the technique of wet-in-wet painting. Soft oil can also be worked with implements other than the brush. Campin used a pointed stick (perhaps the other end of a brush) to indent the fabric edges of a folded linen headdress, while Van Eyck actually scraped the wet paint away to indicate the bristles of a dusting brush.
From "Beyond the Naked Eye"