Introduction to Panels and Boards
Solid panels made from oak were traditionally used by the Italians during the early Renaissance. They were prepared for painting using a gesso ground, composed of chalk or gypsum mixed with animal skin glue to form an absorbent, hard ground. Today, MDF or plywood is widely used, with the benefit of being available in large sheet format and not prone to warping. Not all MDF panels are the same, some may have acidic glues in them so are not the best for permanent oil paintings, so it’s best to check if the glue is pH-neutral.
There are many reasons for painting on a panel or board instead of a stretched canvas:
- Conservators say it is ‘best practice’ to paint on a rigid surface, especially for paints that have the potential to crack, such as oil color, egg tempera, encaustic, and metal gilding, because an inflexible surface is the only way to prevent cracking over time.
- With all types of paints there are also aesthetic reasons to paint on a panel, as the wood or aluminum can become a part of the work.
- Practical reasons for using a panel might include easy transport because they are thin or lightweight and this also makes for easier storage.
- Some artists like the resistance of the surface – it is solid, not bouncy like stretched canvas (though some artists prefer the “give” of stretched canvas).
- Other artists choose a panel for conceptual reasons such as: the rigid structure makes sense with a cityscape, for instance.
Panels and boards are available primed or unprimed. For more information on Grounds, have a look at the Guide to Grounds.
What is a cradled panel?
Cradling is the bracing frame bars attached to the back of the panel. A cradled back increases the stability of the panel and allows you to attach hanging hardware and display your artwork easily, without a frame. The bracing prevents damage at the corners where panels are most vulnerable, while also adding warp resistance for thin panels.
Gesso Panels and Boards
Gesso panels are suitable for a wide variety of techniques thanks to the high absorbency of the smooth surface. The surface of the gesso panel is readily-absorbent, and is receptive and responsive to paint. If a smoother surface is required, the surface can be lightly sanded with a very fine sandpaper.
Canvas Panels and Boards
When canvas or linen is adhered to a rigid surface such as a piece of card or wood, we call it a canvas panel or a board. Canvas panels have canvas wrapped around the board and glued to the reverse, whereas boards have canvas glued to the front only, with shear edges. They are perfect for both quick sketches and more accomplished paintings.
Aluminum Painting Panels
Aluminum art panels make even, rigid, and lightweight painting surfaces. They offer great value with a conservation quality stable support.
Unlike stretched canvases (with wooden stretcher bars) or wooden panels, aluminum panels are artwork supports that will not release gases over time and will barely react to changes in humidity and temperature. The conservation benefits and archival properties of the metal mean that aluminum art panels can easily be stored in damp studios where traditional painting surfaces would warp. Areas on the aluminum painting panels can also be left exposed, as the material won’t tarnish due to its resistance to oxidation. The lightweight nature of the aluminum panels makes them ideal for large artworks which need to be transported.
These panels have specially treated surfaces for paint to adhere to. They are ready for use with all types of painting media, including oil, acrylic, watercolor, gouache, and ink. No further priming is necessary as the paint will adhere to the metal.
Wooden Panels
Sturdy yet lightweight, wooden panels are perfect for painting projects out of doors as well as in the studio. We recommend priming with three layers of acrylic gesso and sanding between layers to produce a smooth yet slightly absorbent surface on which to apply both impasto marks and delicate washes.
The surface of a panel is beautiful and the texture is very smooth. You can prime the wood with white or clear primer and paint directly on it or if you prefer the texture of canvas or paper you can use acrylic soft gel and adhere canvas or paper to the surface, then prime and paint on that.
They work great for encaustic painting and can also be used as a work support or drawing board.
Using wooden panels for Encaustic Painting
Encaustic medium is made up of refined beeswax and a tree resin tapped from the Damar tree which is native to Asia. This mixture is melted together and mixed with pigments for color before being used as paint.
Smooth wooden panels are an ideal surface for encaustic painting as they stand up to the heat incredibly well. Canvas is not suitable for encaustic medium as it expands and contracts and could cause the wax to crack and flake off. Even securing canvas to a rigid board is not ideal as the glue can melt with the heat and lift from the board, causing the wax to separate.
The molten wax must be painted onto a rigid but porous surface which allows it to penetrate into the wood to ensure a good, solid base on which to build up a painting. This is why wooden panels are ideal for encaustic painting. The surface of the panels should be even and smooth with no knots or cracks, and most importantly, untreated, which is essential for encaustic as the wax will not penetrate through any type of varnish or acrylic gesso and the painting will simply slide off the board.
How to protect finished work
Varnish Your Dry Oil Painting
A final varnish will:
1. protect the dried oil surface from scratches
2. accept the pollutants and dirt of the years and when dirty be removable from the painting so it can be replaced with a new clean layer
3. deepen the saturation of the oil paint that can begin to look drier and chalkier as it dries (I think they sometimes look thirsty)
4. even out the surface sheen or change it to matte, satin or gloss
5. seal the painting from absorbing any more oxygen and becoming overly dried out, which means in effect that you will then slow the ageing process
The best practice is to wait to varnish your oil painting until it is thoroughly dry because if you apply varnish before the paint is fully dry the varnish will meld with the still drying paint and no longer be a separate removable layer. It will also form a hard layer on top of a still changing lower layer and that can result in it cracking or wrinkling as the changing oil paint pushes and pulls on it.
There is some confusion about how long you wait for it to be thoroughly dry. The long-standing rule is that it is safest to wait 6-12 months. Gamblin, the makers of the great varnish Gamvar, believe that the 6-12 month rule is too vague and doesn’t take into account the huge difference between the drying time of a painting made with a paint mixed with a fast-drying medium and applied thinly/lightly (much less than 6 months to dry) and a painting with slow-drying colors or mediums painted thickly (much more than 12 months to dry). They also point out that the 6-12 month recommendation originated before the fantastic synthetic varnishes we have now, like Gamvar which is a Regalrez-based varnish. The old natural resin varnishes were both brittle and needed very strong solvents, unlike the synthetic varnishes today that use the more gentle odorless mineral spirits. Gamvar is an excellent varnish because it is a flexible, synthetic varnish that will not yellow. But there is a current misconception among many oil painters that it has unusual properties that allow it to be applied when the painting is only touch-dry. This is not true, so I wanted to mention it in particular. Some artists think that if you use Gamvar you can varnish in just one to two weeks, when the painting is just touch-dry because their varnish has a special quality that allows some oxygen through. But all final varnishes let some oxygen through. Gamblin say ‘Gamvar can be applied when the thickest areas of your painting are thoroughly dry and firm’. Gamvar is excellent but it is not magical and cannot be applied any sooner than other similar synthetic varnishes.
Most artists want to varnish sooner than is recommended, they need to sell it or exhibit it and waiting is a frustrating problem. If you apply paint more lightly with a small amount of a fast-drying alkyd medium, you may be able to varnish in as soon as two months. There are a few different ways to test the dryness, these include: pressing your thumbnail into the thickest part, pressing the flat of your thumb in and twisting, and wiping with a solvent to test for color removal. I generally go by how long it has been, how thickly I painted and what fast or slow-drying mediums I used and if I’m not sure I will gently press a nail into a thick area hoping for no mark. If I have an exhibition coming up then I give myself a varnishing deadline as part of the process, so the paintings need to be finished 2 or 3 months before. If I can’t do that then I use a thin spray of retouching varnish now and a final varnish later.
The best varnish to use will:
1. not change in appearance over time (yellow or darken or become cloudy)
2. remain very flexible because as the top layer of the painting structure it should be the most flexible layer of the painting
3. remain removable with a solvent that will not remove the underlying paint.
A final varnish made with a synthetic resin is better than a natural tree sap resin (damar, copal, mastic, etc) because it will not change in appearance, become brittle or become less removable over time. Some varnishes also offer UV protection.
It is best to store the drying painting in a dust-free environment and to clean it well with a damp cloth to remove any dust prior to varnishing,
Sunken, dull areas are often remedied by the practice of ‘oiling out’ but this is not recommended because the oil will darken the whole painting and create a yellow film, especially if stored in the dark. This change can occur in as little as one year and cannot then be corrected. Oiling out can be done without these problems if the areas are coated very thinly, wiped away well and then the area is painted over, but oiling out should not be used as a final surface treatment. A removable final varnish is the best way to give protection and allow future cleaning, unlike an oiled surface which cannot be removed when it eventually yellows. To prevent sunken in areas, if you find certain pigments (notoriously the umbers) become dull then use a bit more oil with those as you paint. If your whole painting has lots of sunken areas, then your oil is probably being sucked into a too absorbent surface, so you may wish to seal your surface so it is less absorbent.
If you feel compelled to oil out some sunken patches before you varnish, instead you can try applying varnish to just those patches before applying the full coat of varnish. So those areas get an extra coat. Or oil them out and then repaint on top.
Retouching varnish is a good varnish if used in a thin layer for some protection during the waiting period before a final varnish can be applied. But it is not a good solution for creating adhesion between dried layers when you are continuing a painting. As oil paint dries it becomes more and more resistant to solvents, it becomes more permanent. But varnish continues to be vulnerable to solvent always. So if varnish is applied between layers, it may cause the paint to become less resistant to solvent, even when the paint is fully dry. This may create a risk of the paint being removed more easily if the final varnish is ever removed in the future.