Preparing Panels with Shellac

I prefer to make my own materials wherever possible. Be that grinding paints, thickening oils, sizing and priming canvas or preparing panels. In preparing your own materials you develop a better understanding of them, which in turn yields better results. Of course, it also has the benefit of being cheaper.

In this post I thought I’d share how I currently prepare small panels for painting.

Jason

Approach

I use 3mm ply machine cut to size (usually no larger than 30x35cm (else a thicker ply should be used to avoid the panel warping when paint dries). I lightly sand the edges and face with fine sandpaper to remove any splinters and sharp edges and then size (or ‘seal the surface’) with shellac. I apply two thin coats of shellac; leaving to dry and lightly sanding after each coat. And that’s it! Panels can then be primed but I prefer to paint directly onto the shellac face - an idea I picked up from friends in Florence. The wood shows through the paint in places which gives an interesting effect.

The shellac, and sanding for that matter, is better done outside or in a well ventilated room.

Here are some I prepared a few days ago:

Why Use Wood Panels for Oil Painting?

Like stretched canvas, wood has been used as a support for oil paints for a very long time. It is stronger and more durable than linen or canvas and, depending on the finish, might give a smoother surface. These small panels and also cheaper and easier to prepare than stretching linen to the same scale.

Where to get Wood Panels?

You can purchase wood panels from most good art stores. But your local timber merchant should be able to supply and cut ply to size. Or, if you’re lucky enough to have your own woodworking machinery, you can cut them to size yourself. We use Wenban Smith in Lewes who are excellent, always helpful and friendly: https://www.wenbans.com/

Why Size Wood Panels?

Proper preparation of painting supports is essential for longevity of the work. Like linen, wood panels need to be sealed prior to priming and painting. Sizing creates a barrier layer between paint and the support. This stops oil in the paint from penetrating the wood and causing rot, and moisture and changes in humidity from causing the wood to warp.

Sizing also yields an easier surface to apply subsequent paint layers. It reduces a supports absorbency, allowing paint to sit on the surface to be easily moved around rather than sinking in. Note that sizing is different to priming. Generally a primer refers to a coating that prepares the surface for the acceptance of paint.

Why use Shellac?

Although not traditionally thought of as a sizing material shellac is often used in artwork to seal the surface of wooden or other porous supports that will later be painted over. It is easily applied, dries quickly, and is of low toxicity. It can also be used as an isolating film between layers of paint, both oil and water-based. There are some disadvantages though, it is brittle and tends to yellow over time.

What is Shellac?

Shellac are, of course, an american post-hardocre band lead by Steve Albini …..but also … shellac is a resin secreted by the female lac bug on trees in the forests of India and Thailand. It is processed and sold as dry flakes that can be dissolved in alcohol to make liquid shellac.

Shellac is graded by several variables; the two most common are its wax content and colour. The colour can range from pale yellow to a dark reddish-brown and depends on the sap of the tree that the lac bug lives on and the time of harvest. Shellac naturally contains 3 to 5% wax. The wax reduces the clarity of the finish and makes it less water resistant. Some grades are de-waxed, and these have better transparency and moisture resistance but dewaxed shellac has a much shorter shelf life after mixing it with alcohol (about 6 months).

Photograph by Nuberger13 at en.wikipedia - I created this work entirely by myself., Public Domain, https://commons.wikimedia.org/w/index.php?curid=13477833

How to Prepare Shellac?

I generally use premixed shellac which is readily available from good art stores and general hardware stores. I have found the latter to work perfectly well. These will tend to have a shelf life after which the shellac will not dry.

But best results are usually obtained by preparing your own shellac from dry flakes, which can also be purchased from art supply stores. Dry shellac flakes store indefinitely under proper conditions. These should be dissolved in denatured ethyl alcohol. In the UK that generally means Methylated spirits, which is denatured alcohol with additives, including Methanol (hence the name) to make it undrinkable. Be careful with Meths, it is toxic and highly flammable - never use it near an open flame.

The strength of shellac solutions is traditionally measured by a unit known as a “pound cut,” which refers to the amount in pounds of shellac flakes dissolved in a gallon of denatured alcohol. Most pre-mixed commercial preparations are 3-lb. cuts.

Preparing the shellac is simply a matter of leaving the flakes to dissolve for around 24 hours, perhaps longer if it is cold, stirring occasionally.