Part 3 – Wood and Metal
Wood surfaces such as oak, birch, mahogany or pine can provide your artwork with an interesting background with very little effort. Applying one coat of acrylic paint evenly on any of these surfaces allows the wood grain to show through, making it a quick and easy start to any project.
Here are some tips on painting on wood surfaces;
Firstly after selecting your chosen wood surface, I recommend you sand the surface till it’s smooth with fine grit sand paper.
Sanding sponges are ideal for routed or rounded edges, they bend accordingly with the shape of the surface, are easy to manoeuvre, sand evenly and fit well into your hand.
Always sand in the same direction of the wood grain. Never sand against the grain. Sanding against the grain may create scratches and mark the surface which the paint may not cover no matter how many coats you apply.
Sand lightly, while gradually adding pressure as required until you reach a smooth surface.
Make sure that all edges are evenly sanded to smooth, especially if the routed or rounded edges are designed to “frame” your finished artwork.
After sanding, wipe the surface with a dry clothe to remove the sanding dust.
I recommend you always prime the wood; I always use a clear sealer. If you want the grain to show through the background of your work, do not use gesso. Gesso is usually available in white or black and will cover up most of the grain lines.
Lightly sand the surface after priming to remove any roughness in the wood. In most cases any moisture applied to raw wood will raise the surface of the grain. Always apply the basecoating colour in the same direction of the grain.
I recommend you use transparent colours to allow the grain of the wood to show through the surface.
If you have chosen an opaque colour, mix it with glazing medium to create transparency.
When you’ve finished painting the background, apply a coat of glazing medium, this will protect it from mistakes and accidental splashes while painting the design. Glazing medium helps to prevent the paint from soaking into the wood, yet the surface remains paintable.
Always wear a good dust mask when sanding to prevent inhalation of dust particles.
Painting on Metal
Metal surfaces include tin, aluminium, brass copper, stainless steel and wrought iron. I have only ever painted on new surfaces, and they still require some preparation before use, the main issue with metal is its shiny slick surface, so paint won’t adhere to it unless the surface is appropriately prepared or roughened up.
Sanding is one way but not something I recommend as it may result in creating harsh scratches on the surface that will show through your artwork. Even fine grit sandpaper can scratch the shiny surface of metal which can still be visible even after many coats of paint are applied.
Metal must be thoroughly cleaned before painting. Remove any dirt, oil or grease and dry thoroughly. I recommend the surface be wiped with a solution of 1:1 water and vinegar, which will act to etch the surface to prepare it for painting.
Surfaces such as wrought iron and stainless steel contain iron, (otherwise known as ferrous metal) are prone to rust when they come in contact with water. These surfaces require a protective primer which contains rust inhibitors before painting on them with acrylics.
After priming, either with primer or a water and vinegar solution, I would recommend a coat or two of Gesso before you begin painting.