An increasing number of metallic powders for decorative purposes have become available over recent years. The range includes speciality colours, iridescent, pearlescent and sparkle colours.
They are made from metal or mica flakes or a mixture of both. Metal powders are made from copper, tin, zinc and aluminium and alloys of these metals. By blending a wide palette of colours can be created. Often they are heated to develop new deep rich shades of colour.
Mica Powders or Flakes are a non-toxic, naturally occurring substance that is often used in cosmetic powders to give them a soft lustrous sheen. By mixing with earth and other pigments, coating with titanium dioxide, beautiful pearlescent and iridescent colours are developed. Being chemically inert they can be mixed with any medium.
When we speak of Metallic Powders they are a mixture of Metal and Mica Flakes. It is a term used to describe the wide range of materials that are used in the automotive industry to make metallic paints. They are ground to yield a wide range of sizes. Coarse powders reflect with a brighter, more brilliant finish. A smoother, duller finish is achieved with a finer pigment.
Metallic Powder Mixing Guide
They may be mixed with any medium including lacquers, oil varnishes, acrylic resins, waxes and polyurethane resins.
Beautiful jewellery effects are possible using polyurethane resins and casting into moulds dusted with metallic powders. Faux metal effects are made by cold casting with up to 50% content of metal powders.
Use a good quality clear reasonably thick coating medium as a base rather than a paint which would obscure the metallic effect. The viscosity of the medium helps to keep the metal powders in suspension to create the illusion of depth.
Please note that it is not recommended to store aluminium powder mixed with an acrylic medium for any extended length of time as it develops a gas that cause problems. Also while it is quite safe to mix metal powders with plasters as well as resins, do not mix with Forton MG.
Mixing ratios can vary widely depending on the effect desired but a good starting ratio is 1 part metal powder to 8 parts medium. While for mica powders start testing with 1 part mica to 6 parts medium.
While cold casting with metal powders the polyurethane resin can be loaded with as much metal powder as it will take and still be pourable. This could be 50%. So you can see the variation possible with these versatile decorating materials.
Cover the entire object with an even layer of gold size and allow to dry till it has the same tack feel as adhesive tape. Apply the metallic powder with a soft brush similar to one used for applying cosmetic make up. Build up a sufficient powder layer without over brushing to give you the effect you require.
How to Achieve a Patina Effect
All the metal powders can be given a patina using a combination of chemicals including acids such as acetic acid or vinegar and substances such as bleaches. A wide range of Sculpt Nouveau patinas are available for special effects. You can give a similar effect to mica powders with the use of paint or coloured glazes.
Beautiful effects are possible by using waxes made by mixing beeswax with a little turpentine.
Avoid making the powders airborne. Use a small scoop to remove the powder from the container rather than pouring it out. Make a paste using a spatula on a small sheet of glass or similar adding the medium in small amounts. Wash your hands thoroughly after using the powders. For complete protection use a dust mask.