Framing & conserving a painting

I don’t offer framing for my portraits, however I hope you will find some of this advice on framing an painting useful. Feel free to contact me with any questions once you’ve received your portrait and I’m happy to make suggestions.

Paintings need to be framed in different ways, depending on the medium they are made with, and what sort of surface they are created on. Whilst watercolour or gouache paintings on paper are framed behind glass, just like pencil and charcoal drawings, oil paintings traditionally are not. With acrylic paintings it’s less clear whether or not they should be glazed, with various arguments in favour and against. 

We’ll start with oil paintings and some general framing information and then further down we’ll look more specifically at how to frame a watercolour› using both a frame and a mount (mat) and how to frame an acrylic painting›


Why oil paintings have always been framed without glass

Oil paint has been around for many centuries and pre-dates the availability of large sheets of plate glass that could have covered historical or biblical paintings. Once fully dry oil paintings are less vulnerable to damage than watercolours, drawings and other media created on paper and less in need of protection behind glass. There could be potential for the glass to damage any thickly-applied paint, and glass may trap moisture behind it – potentially leading to rotting in the canvas if the painting is unable to ‘breathe’.

Oil painting frames

This last possibility is most likely to occur during the first few years of a painting’s life and it is during this period that it is essential that a painting isn’t framed with glass. This is because oil paint actually takes an incredibly long time to fully dry. Although a painting may feel touch dry within a week of the application of the last layer, chemical changes continue for many years as the oil that has been added to the pigment slowly oxidizes and sets the paint. This will happen at different rates in each of the painting’s layers depending on how thickly the paint has been applied in each, and with what ratio of oil-to-pigment. In fact these changes may not be fully completed for 70 years! It’s in the first few years however that the paint layers are most likely to shift around and the presence of any moisture and exposure to variations in temperature may cause cracking and flaking.

After several years, it’s generally considered safe to re-frame a painting behind glass, should you really wish to and provided that you hang your painting in stable and dry conditions. Glass does provide protection against household pollutants including dust, soot and so on, but this needs to be balanced against the drawback of putting a painting behind reflective glass which may create a glare and compromise your view of it. A varnished oil painting will be fairly well protected against dirt if hung in a suitable place and dusted regularly with a soft brush. If you do glaze your oil painting ensure that the framer adds a ‘spacer’ so that the surface of the canvas or board is kept clearly separated from the glass by as much as possible – the image below shows the huge gap which a museum framer will maintain to encourage air circulation. You can read more about the different types of non-reflective frame glass available here

Frame with spacer

Choosing a frame for an oil or acrylic painting

There’s an infinite choice of frame styles, and the one you choose (indeed, whether you choose to frame your painting at all) is really a matter of personal preference. Of course you’ll want a frame colour that compliments those within the painting, however a typical frame in a neutral metallic or wood finish will generally go well enough with any paint colours. Your framer will choose a selection of frame samples to hold up against your portrait and help you find one that you like.

If you have a smartphone, take a photo of the you are going to hang or place your portrait in when visiting a framing shop. This will help your framer to suggest appropriate complimentary colours and will give him or her a sense of what style and colour of frame will suit your décor.

As a general rule of thumb, a painting will pair best with a frame that matches the age of its subject. A modern painting may therefore look slightly odd in a very old-fashioned style of frame and better in one in a contemporary style, whilst a very old painting may suit an older style better. However whilst the relationship between painting and frame should ideally be a harmonious one, the style of the artwork/frame and the style of your room could be deliberately contrasted if you prefer to do so. An old painting in an gilded ornate frame can look very striking in a room with very contemporary and even minimalist furnishings!

Frame samples

Frames may be made of wood, aluminium or sometimes a stiff plastic like polyproprane. Ornate old fashioned frames are not carved from timber but will have mouldings made of plaster, glued to a timber frame and gilded with a metallic coating. Often frames will contain a mixture of both gilded and un-gilded timber: you can see a couple of examples of this in the image above.

 All traditional frames of this type are similar in construction, having a rebate cut into them called a ‘rabett’ which provides a lip of around 6 millimetres (1/4″) to notch over the painting and hold it in place. Behind the a framer will often fix a backboard to protect the back of the canvas. If you want a frame in an unusual shape such as an oval this may be difficult to source in a bespoke framing shop and you may have to source one ready made or buy an antique.

Some different framing options:

Linen liners

Unlike a drawing, a painting is framed without a mount (or mat, for those in North America) Picture mounts are what create the card border that you’ll see around a framed drawing or painting on paper, and are placed between the artwork and the glass. They serve the purpose of creating a space between the two in order to prevent the glass from damaging the surface of the painting or drawing, and allowing air to circulate in between. A painting which is framed without glass has no need of a mount. However you may see paintings framed with what look like an inner mount, such as in the first image below.

Picture frame with linen liner
Painting frame with mock timber mount

In fact this is a linen liner. It is made from fabric-covered timber and is not designed to sit behind glass but instead slots into the rebate (rabett) inside the picture frame to supply the same ‘visual break’ that a mount creates, and to draw the eye into the subject of the painting. Typically it will be made of unpainted linen but with a metallic-finished fillet applied to the beveled edge. Various widths are available and as a liner isn’t integral to the frame but is an addition, you can choose one that you prefer and have it fitted to your frame. Amongst antique frames you may sometimes come across one like the example above where a plain, gilt-finished piece of timber has been used as a liner to create that visual break between the painting and its highly ornate frame.

Box frames

You will frequently see ‘box’ or ‘tray’ frames (sometimes also known as a ‘shadowbox frame’ or ‘floating frame’) if you visit a modern art gallery. With a box frame, a plain rectangular wooden frame is created on top of a baseboard, and the painting is placed within it, with a gap between the frame and the edge of the canvas so that the canvas edges are still visible. Typically the frame and the painting canvas are the same depth, so that the frame doesn’t protrude further than the painting. The frame itself can be any thickness from about 8mm (just over 1/4″) upwards and is usually made from painted timber or unpainted aluminium.

Box frame example
Box frame example

The shadow gap created between frame and painting may be only a few millimetres (1/8″) or a really wide gap may be created as a means of giving the artwork extra prominence and size. A box frame is really a way of framing but not framing : lending importance to a canvas that you don’t want to frame in a traditional and old-fashioned way but don’t want to hang directly on the wall, either. If your painting has been finished on the sides of the canvas too (this is known as a ‘gallery wrap’) a box frame is a good way of framing that displays those edges instead of hiding them. Because the edges of the artwork are revealed, a box frame is really only suitable for framing a work made on canvas or some kind of board but not for one made on paper.


Acrylic paint and oil paint are very different in their chemical properties. Instead of an oil binder, acrylic paint uses a water-based emulsion of acrylic polymer as the medium to bind the paint with the pigment and set it as it dries. As a result it dries very fast and will be fully dry within only a matter of hours. In this sense, acrylics are much more stable than oils. The paint layers have more flexibility, and in stable climactic conditions they will suffer very little movement.

However, because acrylics will soften in great heat and contract in cold conditions they are actually more vulnerable than oils to cracking as a result of being exposed to temperature extremes. Therefore hanging your acrylic painting in a suitable place is very important, and we will talk more about this below. In terms of the implications for framing, the fact that acrylic paint softens at a high temperature means that it may actually absorb any dirt that is sitting on its surface if that temperature reaches 30° Celsius (86°  Farenheit). Acrylic paint is similar in its chemical properties to decorator’s emulsion and it attracts dust and dirt in the same way that painted walls do. The desire to protect an acrylic painting from household pollutants might therefore be considered a persuasive argument in favour of framing it with glass. However, although a work in acrylic will likely be less vulnerable to flaking paint than an oil painting should any trapped moisture be allowed to condense on its surface, some would argue that there is still a risk of rotting in the canvas and that glass should be avoided in order to let the painting ‘breathe’.

For most people the question of whether or not to glaze a work in acrylic will come down to aesthetic considerations. How bothered are you that your view of the painting may be partially obscured by the glare sometimes created by glass? Will you be able to appreciate your artwork fully in the same way? If you do glaze your acrylic painting, make sure that you hang it in a suitably dry wall without any damp problems. If you decide not to  glaze, make sure to regularly dust your acrylic painting but very gently using only a soft artist’s brush or makeup brush and not a cloth. Never clean it with water, or apply any cleaning solutions.

Oils and acrylics: to frame or not to frame?

If you got to an art gallery or museum you’ll notice how many contemporary paintings are not framed at all, and are simply hung directly on the wall. The fashion for hanging paintings without a frame really stems from the perception of contemporary art since the mid-20th century as something that should speak directly to the viewer, with no frame creating a barrier between the two. Here’s an interesting article you may enjoy on the topic of the aesthetic of the frame.

Whilst your painting may not be intended for a gallery, hanging it directly on the wall does certainly give a more contemporary look which you may prefer if your home décor is more modern. If you intend to do this when you commission a painted portrait, make sure to let the artist know in advance so that they select a deep canvas (this will look better on the wall than a thin one) and also one with a ‘gallery wrap’ – meaning that the canvas has been stapled to the wooden stretcher frame on the back instead of on the sides so that the staples aren’t visible.

Hanging an oil painting


Watercolour paintings have very different framing needs to oil and acrylic paints because they are created on a paper and are therefore very much more delicate and vulnerable. The binder in watercolour paint which is mixed with the pure pigment is usually ‘Gum Arabic’ or sometimes ‘Synthetic Glycol’. These mediums dry very quickly and remain stable, but they offer less protection to the pigments they are bound with than either oil or acrylic polymer mediums. Furthermore, watercolour paintings cannot be varnished to give their paint layer an added protection. Therefore protection behind glass is considered essential. This in turn necessitates the use of a mount (known as a mat, in North America) which is sometimes also called a ‘passepartout’. The mount borders the painting and separates paper from the glass, preventing direct contact between the two and allowing air to circulate in between. A further piece of mountboard called the ‘back mount’ sits behind it and the artwork is affixed to it using acid-free tape. Failure to allow the painting to ‘breathe’ in this way may cause moisture to become trapped in the paper where it may cause mould and mildew to grow.

Framing picture diagram
Framed watercolour painting

When framing an artwork created on paper, using acid-free and lignin-free materials as much as possible is an absolute must. Acid and lignin  – a molecule found in the cell wall of plants, including in wood pulp – if present in the mount, back mount or even the backboard will cause numerous problems. The core of the mount that is visible around the edge of the aperture will eventually turn to an unattractive straw colour. Even worse, acid will eventually leach out of the mount and into the watercolour painting creating an brown stain effect known as ‘mat burn’ and encouraging ‘foxing’ (small brown marks thought to be caused by fungal growth on the paper surface) which thrives in acidic paper where any moisture is present.

Choosing a ‘conservation’ or even better ‘museum’ grade of mount is the key to preventing these future problems. Most mounts are marketed as ‘acid-free’ these days but such products may only have been given a protective coating which will eventually degrade and allow acid to leak out. ‘Conservation’ mounts are made from wood pulp that has been chemically treated to remove acid and lignin and achieve a neutral PH value. ‘Museum’ grade mounts are even better as they are made from cotton fibres which are naturally acid and lignin-free. If you take your painting to a professional picture framer, they should be aware of and stock most of these options.

Having outlined the conservation requirements when framing a watercolour painting, how do you choose between the bewildering variety and styles of mounts on offer? This article on framing a drawing explores some of the many different options. It also covers the different types of glass and acrylic alternatives that you might choose to frame your painting, including UV-repelling options that will reduce the risk of pigments in your painting degrading and fading over time. Watercolour paintings are particularly vulnerable to fading because the Gum Arabic used as a medium to bind the pigments does not protect them as well as oil or acrylic mediums. It’s important to remember however that UV-deflecting glass only protects against UV light. It gives no protection against the rest of the light spectrum, and so it’s still very important to select a shady wall to hang your painting out of direct sunlight.


For paintings in all types of medium it’s important to avoid any source of damp and extremes of temperature, and particularly fluctuations of temperature. Above we’ve discussed how humidity can cause mildew and foxing in paper; it will also cause buckling and bowing especially when combined with excessive temperature variation.

With oil and acrylic paintings damp will cause rotting in the canvas and – combined with any significant fluctuations between heat and cold – will encourage movement in layers of paint and eventually flaking and paint loss. Paintings in all mediums are also vulnerable to colour fading in direct light as the pigments they contain may break down from exposure to UV. Here are some conservation practices to help you avoid any of these issues:

  • HEAT: Don’t hang the painting above a radiator, near an oven, or any other source of heat. A unglazed painting placed in a room with a working fire will risk discolouration, and placing it in a room with a candle will also cause soot damage. Don’t shine a spotlight directly at it.
  • DAMP: Never store a painting that isn’t currently on display in a basement, garage, attic or shed even temporarily! Don’t hang a painting on a damp or newly plastered wall or too near to a vent.
  • LIGHT: Try to avoid ever hanging a painting on a wall that gets lots of direct sunlight. A shady wall is always preferable. Avoid placing it too close to an electric, non-LED light which may emit a small amount of UV and could also overheat your painting if it’s too near. Don’t use a ‘picture light’ designed to be mounted just above the top of a frame.
  • CLEANING: If your painting is unglazed, gently dust it regularly with a soft artist’s brush from an art shop or a soft makeup brush, but don’t use a cloth which may damage or scratch the surface of the paint. Don’t use water or any kind of cleaning product on it: if your painting really needs cleaning, take it to a professional restorer.

Pin It on Pinterest

Share This