Since their invention in the 50s, Acrylic paints have dramatically gained in popularity. What makes acrylics so attractive is the seemingly unending number of different ways in which you can use them.
Benefits of Acrylic Paint
Acrylics can be used to achieve a variety of effects, from the heavily textured canvass achieved by oil paint, to the light and airy translucency of watercolors. They are not as expensive as oil paints and dry quicker, allowing the artist to apply multiple layers of paint without long waiting times in between, dramatically reducing the time it takes to complete a piece.
On top of that, Acrylics can be applied to almost any surface: traditional canvas, paper, wood, fabric, metal, glass, plastic, stone, leather and more. Before you start painting, most surfaces need to be prepared so that your Acrylic colors go on smoothly and stay bright and looking like new for a long time. Here are some basics on choosing and preparing different types of surfaces for use with most Acrylic paints:
How to Prepare Surfaces for Acrylic Painting
The most popular type of traditional canvas among artists is cotton. It is durable and provides a smooth texture for your paints. Synthetic canvas is best when you want the smoothest texture. It is exceptionally strong and in particular resistant to the slight corrosiveness of the acrylic medium. Jute can also be used, it is low-priced and provides a unique texture desired in certain works.
Canvas is now sold in most art-stores ready to used, primed and stretched over wooden frames, or glued securely onto a hard cardboard backing. When using raw canvas, however, you must prepare it before use.
Stretch the canvas over a wooden frame so that it is firm, but not too tight. Stretching it too tight may warp the frame and decrease the flexibility of the canvas when drying paint shrinks on it. Staple the canvas in place. Paint a few even coats of gesso to prime the canvas after stretching.
There are different kinds of paper that can be used for Acrylics. Most paper will be labeled specifically for the medium it was intended to be used with. Bristol Board, for example, is designed specifically for use with Acrylics and doesn’t need any preparation.
Generally, heavier weight paper is recommended as it will be less likely to warp while painting. Tape the edges of your paper to a flat surface with masking tape, as you would when working with watercolors, to prevent it from warping when wet.
Wood provides steady and long-lasting support for acrylic paints and most woods have excellent paint-absorbency properties. Use hardwoods in favor of pressboard or plywood, as these softer varieties have a tendency to lose their shape over time. Before you paint on wood, purchase some coarse and some fine sand-paper. Sand the surface of the wood, if necessary, with the coarser sand-paper until it is smooth.
Apply a coat of gesso using wide, even brush strokes all running in the same direction. Allow the gesso to dry before lightly sanding it to smoothness with the fine sand-paper. Apply another coat of gesso with the brushstrokes running perpendicular to the previous coat. Repeat the process, sanding in between each coat, until the surface is smooth and even.
Acrylics can usually be applied directly to a great variety of fabrics such as cotton, felt, silk, velvet, and flannel, but cotton provides the most even and easiest to work with surface.
Wash the fabric before painting to remove lint and any oils or chemicals that may interfere with the paint. Lightly stretch the fabric out for more comfortable painting. Mix some Fabric Medium or Flow-Aid Medium with your paint prior to painting for best results.
Tip: Always test your acrylics on a small square of the fabric before you begin painting to ensure the fabric is compatible with the paint and the colors achieve the desired effect.
Acrylics do not naturally adhere well to very smooth shiny surfaces so if the metal is highly polished, use heavy-duty sandpaper to sand it until it is matte and slightly rough to the touch. If you have the means, you can also use sandblasting for a more uniform effect. A diluted lye solution will work on Aluminum to create a more workable surface.
Once you’ve achieved the right texture, clean and degrease the surface. Apply gesso or an industrial primer, allow it to completely dry and do a test to make sure paint adheres properly.
A glass surface can be made rougher with sandblasting, or it can be acid-etched in order to achieve the necessary roughness for the paint to grip. Clean and degrease the surface and apply an industrial primer or gesso. Let it dry and test for adhesion the same way as with metal. For best results, use a few thin coats of varnish to seal the paint and prevent scratches.
Plastic should be lightly sanded with fine-grade sandpaper until it feels slightly rough under the fingers to allow the paint to grip. When painting on clear plastic, use clear gesso or varnish to prime the surface. Seal the painting with varnish once complete to prevent from an accidental scraping of the paint.
Thoroughly clean the surface; ensure it is free of any grease, wax, oil, dirt or loses particles. Ensure that the surface is completely dry, and in the case of using a concrete block, that there are no silicones in its mixture.
Evenly rub a gel medium into the surface and allow it to dry if desiring less texture for your painting. Use transparent gel when the desired effect is for the stone surface to lightly show through the paints. Apply a few coats of gesso for a matte look.
Painting on suede is the same as on any other fabric; use a flow-aid medium to help the pain go on evenly. Other types of leather must be first decreased to prevent Acrylics from peeling. Rub the surface thoroughly with alcohol to remove oils and dirt from the surface. Once finished, use a spray-on varnish to protect the paint.
How to Test Adhesion in Acrylic Paint
When working with new and unusual surfaces, it is always a good idea to perform an adhesion test before continuing with the majority of your work. To perform the test, choose a small area of the new surface you are testing, prepare it in an appropriate manner and apply the paint to the surface. Let the paint dry thoroughly.
Wait 72 hours, or longer if the humidity in the atmosphere is high, for the paint to fully set. Score the surface in a cross-hatch pattern with a sharp object and firmly apply some masking tape over the scored surface. Slowly remove the masking tape. If any paint comes off, then you may wish to try a different priming method, or a different surface altogether.