There are several different types of ornate picture frame. They include hand carved ornaments made from solid timber, hand-made composition ornaments applied to a pre-joined frame, machine-made compo frames and mechanically embossed timber ornamentation.
Frames have been made from solid timber for several thousands of years. There are examples from Ancient Egypt and there is a solid link between the Roman Catholic Church and ornate framed religious artworks for at least the last 1000 years. The Egyptians discovered methods of applying gold leaf to timber by applying a bole made from Armenian clay. The clay provided a smooth base that the gold leaf could be applied to and the red color of the bole imparted a luscious glow to the thin layer of gold applied over it. Modern gilding today still uses identical methods to fix gold leaf to timber.
In the early European examples the ornaments were carved to match the architecture of the day. The frames were often designed by the artist in consultation with the artisan framer. In many examples the frame was made prior to the artwork being painted. The panels and canvasses that the artist would prepare used similar materials like animal glues combined with calcium carbonate or chalk to make a sound surface to commence painting on.
The carved frames were often gessoed with the same concoction of rabbit skin glue, water, deadened plaster and chalk. The gesso mixture was applied warm from a double boiler and built up over several layers. The final layers prior to gilding were done with a bole mixture where often the lowlights were covered in a yellow ochre toned clay and the highlights were reddish toned. The yellow tone provided a mask for where the hollow section of ornament may be left un-gilded. It was difficult to get the gold leaf down into every hollow so the yellow tone helped disguise the missing leaf.
Framers wanted to make ornate frames quicker and also wished to replicate a particular design to save time from the laborious task of carving so they developed a mixture called “compo”. The composition as it was known was a secret recipe basically made from rock resin or rosin that had been melted with raw linseed oil. This molten resin mix was then combined with hot rabbit skin glue and mixed quickly to emulsify the oil and water mix. As the component were being blended the addition of a filler in the form of powdered chalk or whiting was added to give the material body.
The composition could be made in a large batch and stored as bricks to be later heated and reactivated into a pliable molding compound.
Ornaments could then be carved once and then either by making the carving as a negative mold or by copying the ornament by using molten shellac or molten resin be copied by pressing the hot compo into the mold and then applying the flexible ornament to the frame before it had cooled and set hard.
Many replica frames are still made today by the composition method.
Modern use of silicone has enabled easy replication of carved ornaments although there are several practitioners of the old methods using traditional materials.
The ornate swept frame where an ornament is applied to a timber base and then gilded is a common example. The gilding in this case is usually done with schlagmetal or Dutch metal leaf. An imitation gold made from a mixture of copper and nickel. The schlagmetal is applied using an oil gilding method where a slow drying varnish is applied to the prepared frame and then after a set time just before the varnish is totally dry the leaf is applied to the surface. If the leaf is applied too soon the finish is dull and lifeless but when the timing is right a bright gold surface is achieved. This type of gilding needs to be protected with layers of shellac and is also often varnished to prevent tarnishing occurring.
Most commercial gold frames are made with artificial gold leaf like schlagmetal due to the low-cost of the material and the speedier application of the finish and preparation of the underlying timber.
Modern ornate gold frames that can be purchased in lengths are usually made by a mechanical compo machine. The machine consists of a feeder type system where a timber profile is drawn through the machine passing under a large embossing wheel that has the pattern engraved on to it. A modern mixture of synthetic compounds or wood mast much like a wet mixture of MDF is pumped onto the frame just prior to it passing under the embossing wheel. The wheel stamps the pattern into the mixture as the timber passes through the machine.
The profiles are then dried and can be finished in a number of ways ranging from painting, gilding or synthetic foiling with a hot stamped foiling machine. The foils are available in a wide range of finishes mimicking all types of finish.
The other common method of producing ornamental timber finished frames is by using a mechanical embossing machine. The embossing machine is similar to the composition machine but instead of applying a layer of compo to the frame the wheel with the pattern on it is heated up by a blow torch type set up. The wheel is heated gradually by rotating it through the gas flame until it is hot enough to scorch the timber. Then the pattern is embossed into the timber frame molding under heat and pressure. Usually this type of frame is then stained to a dark color to help conceal the odd scorch marks.
There are different molding techniques being developed all the time for modern replication of ornate picture frames. These methods usually involve mass reproduction of a particular design just to meet a specific price point that is acceptable to the market. They are not usually used to make unique hand-made frames to suit individual artworks.
It is worth understanding the ancient methods and appreciating that the techniques developed over the centuries have a place of value. A modern picture frame may last a century but this is often unlikely whereas antique traditionally crafted frames have lasted a millennium.