Introduction to Vitreous Enamelling

Vitreous (glass) enamel is the application of finely ground glass onto metal, which is bonded by heat, and has been used for over a thousand years in jewellery and metal working. You can achieve many different effects through extensive techniques, from intricate painting, to the use of gold leaf or to graphic stencilling.  Usually multiple layers of enamel are applied with different rounds of firing to achieve the desired results.

Health and Safety

• Keep the work area free from food or drink to avoid contamination and accidents
• Enamel is a powder so use in a well ventilated area and use a respirator mask designed for dust
• Wear heat-protective gloves taking items in and out of the kiln  
• Wear protective goggles to protect eyes from shards of fired enamel which may ‘ping’ off a piece, and use welders goggles if firing for long periods of time or vocationally
• Use water when sanding or stoning enamel to prevent inhalation of airborne glass particles
• Pieces coming out of the kiln are HOT! Allow to cool completely before handling.

Setting Up a Workspace and Equipment

Kilns and enamel are safe to use in the workshop or the home, providing health and safety procedures are followed, away from distractions like children and pets. For a productive and safe workspace, have a clean and tidy work area, such as a table or work bench with suitable heat protective surfaces, good ventilation and protective equipment.

What you will need:

• Kiln (gas or electric)
• Protective heat boards
• Trivet and/or mesh
• Kiln tongs
• Pestle and Mortar
• Good quality paintbrushes
• Quills
• Sieves
• Palette knife
• Small pots
• Tweezers
• Glass brush
• Wet and dry paper
• Samples from Cooksongold Staff Training Workshop (Lana Crabb)   Carborundum stone
• Diagrit
• Pumice

Samples from Cooksongold Staff Training Workshop (Lana Crabb)

Metal and Preparation

Enamel can be used on a variety of metals, most commonly copper, fine silver and 18/22ct gold. Alloys containing zinc and nickel are unsuitable as the enamel tends to react and not fuse to the surface.

When enamelling, cleanliness is key! If using copper, use abrasive papers to remove any oxides, then pickle. For fine silver and gold, a brass brush can be used, or a glass brush under running water with protective gloves on.

Types of Enamel

• Frit – large lump of enamel, ready to be ground into a powder
• Opaque
• Transparent
• Opalescent
• Lead-free – Many enamels contain lead to enhance colour, but lead-free versions are less of a health and safety risk, especially suitable for students and hobbyists. 
• Flux – clear enamel, used as an undercoat to prevent interaction between the metal and enamel and to keep the colours bright, can also be used as an overcoat.
• Liquid Enamel – Finely ground enamel in a liquid suspension. Can be painted, sprayed or dipped onto metal.
• Painting Enamels – Very finely ground oxide, applied similarly to watercolours.
• Millefiori – cross-sections of glass rods with decorative details (similar to seaside rock)
• Threads – thin rods of glass for decoration
• Beads – small glass beads for decoration or creating texture
• Decals – ceramic transfers (similar to temporary tattoos) applied to the surface and fired in

Other things to know:

• Mesh – applies to the fineness of the enamel particles. Sometimes a finer powder is required, and the enamel is ground in a pestle and mortar with water, then rinsed.
• Soft enamel – fires between 730-780 degrees Celsius
• Medium enamel – fires between 780-840 degrees Celsius
• Hard enamel – fires above 840 degrees Celsius

Begin Enamelling

Step 1: Counter Enamel

Metal warping due to the high temperature of the kiln can cause cracks in enamel so it is important to apply a layer to the back beforehand, to create equal stress on both the front and back of the piece. Thinner and/or larger pieces are more like to warp, as are flat pieces, rather than domed pieces.

• 1mm or lower should be counter-enamelled
• 1mm-1.3mm may need to be counter-enamelled depending on size and shape
• 1.3mm of thicker does not usually need to be counter-enamelled
• Counter enamel can be applied using sifting, wet packing or with liquid enamel (See the image alongside this article)

Step 2: Applying Enamel

Depending on the enamels used, and the desired effect, a variety of methods can be used:

• Sifting – dry powder can be applied directly onto the metal or over a flux layer
• Wet packing/laying – finely ground powder suspended in water can be applied to the metal or flux layer, using a paintbrush or quill
• Painting Enamel – special painting enamel powder is mixed with painting medium (often pine oil) and painted onto the surface of a flux or coloured layer (usually white) and fired in layers
• Liquid enamel – can be painted, sprayed or dipped

Step 3: Firing

Any moisture needs to be dried off before firing, especially oil from painting medium, as the oil will burn. This can be done by leaving wet pieces under a lamp, or on a trivet above the kiln. Alternatively, liquid can be burnt off by briefly holing the piece, on a trivet and using kiln tongs and gloves, in front of the open kiln door before firing.

Firing times will vary depending on the piece and the temperature of the kiln, usually between 30 seconds and 2 minutes. Make sure your kiln is set to the right temperature for the enamels you are using.

When firing the enamel will go through three stages as it melts:

1. Crystalline/granular   

2. Orange peel effect

3. Smooth and fully fired

Other Techniques

Cloisonné

Using fine wires of copper, silver or gold to create sections or decorative effects in the enamel. Used with the wet packing technique, wires are placed onto a flux layer and fired in, then colours are applied and fired in layers, until the piece is one depth. At this point the piece is stoned back and re-fired for a smooth finish.

Champlevé

Engraving, etching or repoussé is used (i.e. cutting away/creating different depths in the surface of the metal) and applying transparent enamel. The effect gives different depths of colour and pattern to the piece.

Plique-à-jour

Often thought of as the stained glass window effect of enamelling. Metal is saw pierced and the piece placed on a mica sheet, to prevent the enamel falling through as it would on a trivet on mesh. The cells are then filled and fired with layers of enamel using the wet packing technique. Once the depth of the metal is reached, the piece is stoned back, taken of the mica sheet and re-fired for a smooth finish.  

Foils and leaf

Enamelled earrings by Caroline Finlay

Fine silver and gold leaf and foil can be fired into the enamel to create interesting and beautiful effects.

Foil is more robust than leaf, can be manoeuvred and used under a transparent enamel or flux.

Leaf is very fine and used as a finish, generally in the final firing, with no flux or other layer on top.

 Things to remember!

• Cleanliness and keeping colours separate and uncontaminated is key to successful enamelling.
• Finished enamelled pieces will not withstand being heated again, so think about how you can solder beforehand, cold connections and set pieces into mounts.
• Finished pieces are fragile – protect them and treat them with care.

Enamelled pendant by Ruth Ball

Inspiration

Some really useful books:

• Enamelling by Ruth Ball
• The Art of Enamelling by Linda Darty
• Enamelling on Precious Metals by Jeane Werge-Hartley

source https://www.cooksongold.com/blog/learn/introduction-to-vitreous-enamelling/