Should you Frame a Painting Behind Glass? (Complete Guide)

If you have just bought a new painting or are looking to frame your own creations, you are probably wondering the best way to display and protect your artwork.

Framing behind glass is a popular method of protecting a work of art, but that does not make it suitable for all, and in some cases risks causing more harm than good.

Whether or not you should frame a painting behind glass is not entirely without debate, however there are some general guidelines for each medium, whether that be acrylics, oils, pastels or pencil. In this article I will explain why certain mediums require glass protection, and why others do not, depending on their properties.

The Quick Answer

Oil paintings on canvas do not require framing behind glass. Acrylic paintings also do not require being placed behind glass, unless exposed to very high temperatures. Pastel, watercolour paintings and pencil drawings on paper require additional protection, so framing behind glass is recommended.

Acrylic Paintings

Under most conditions, acrylic paintings on canvas do not require framing behind glass. This is especially the case when the painting has been varnished, as this will provide protection from dust and dirt, allowing the artwork to be cleaned without damaging the paintwork.

Many artists will varnish their acrylic paintings to unify the sheen of the artwork, and to also provide a barrier between the paintwork and potential contaminants.

Acrylic varnishes with UV protection are also available, which can not only protect the painting from dust and dirt, but also the affects of sunlight.

For acrylic paintings on stretched canvas, there is the option to hang the painting without any additional framing. This minimalist style can suit many homes and styles of art.

There is also the option to frame a canvas in a frame without glazing, either in a traditional frame or in a contemporary style-floater frame. Floater frames leave a gap between the canvas edge and the inside of the frame, giving a contemporary feel to the finished artwork.

An acrylic painting by Amber Tyldesley, framed without glass in a floater frame.

Perhaps one instance where you may feel the need to frame an acrylic painting behind glass is if the artwork is to be kept in a hot environment. Acrylic paint can soften in hot temperatures, allowing dust and dirt to settle within the paintwork.

If your acrylic painting is on paper, rather than canvas, framing behind glass is a good option to protect the delicate paper from damage.

Oil Paintings

Similarly to acrylic paintings, in most situations it is unnecessary to frame an oil painting behind glass. For aesthetic reasons alone, framing behind glass is likely to cast reflections and, in the case of impasto (thickly textured) oil paintings, can detract from this aspect of the artwork.

Oil painting by Amber Tyldesley, framed with a linen slip and black frame, without glass.

Oil paintings require a long time to dry, and often years to fully oxidise and cure. Oil paintings, especially once varnished, are very capable of being displayed without any additional glazing.

Oil paintings should be allowed to breathe, as the risk of trapped moisture caused by framing behind glass could degrade the paintwork and canvas.

Oil paintings on paper are an exception, and framing behind glass is recommended. However you must ensure the painting is fully dry to prevent trapped moisture.

Pastel, Charcoal and Pencil Drawings

If you have ever worked with pastel or pencil mediums you will already know how they are prone to smudging if touched.

Unlike oil and acrylic paintings, pastel and pencil pieces do not dry to a hardened state and are therefore vulnerable to physical and moisture contact. For this reason pastel and pencil artwork on paper must be framed behind glass for protection.

It is also possible to purchase UV protective glass, which will not only prevent damage to the artwork but will also provide some resistance to fading.

When framing pastel and pencil artwork, most will advise making sure it does not come in direct contact with the glass. If the pastel or pencil drawing touches the glass, the particles can transfer onto it, risking damage to the artwork.

For this reason, a mount or slip is often used within the frame to provide a sufficient gap between the artwork and the glass. You may also wish to avoid using plexiglass, as the static from this surface may attract pastel particles even if a mount is used.

As they are prone to smudging, pastel and charcoal artworks can be difficult to frame and require an understanding of the mediums to prevent damage. It is therefore recommended that they are framed by a professional if you are inexperienced. 

Watercolour Paintings

Watercolour paintings must be framed under glass for a few reasons. One reason is that they are usually completed on paper, which is delicate and vulnerable to moisture damage and physical contact.

Watercolours will reactivate if they come into contact with water, causing the colours to run. Placing the artwork behind glass will prevent damage from moisture, in addition to preventing dust from settling on the paper.

Watercolour paintings are very vulnerable to accidental and environmental damage, both of which can irreversibly spoil the artwork. Framing behind glass is the best way to preserve the artwork for the future.

UV protective glass is a good option to extend the lifespan of a watercolour piece. Watercolours can be prone to fading with exposure to light, even when it is not directly shining on the artwork.  

The beauty of a watercolour lies in its subtle colour and tonal variations, so even small changes can make a difference to the overall artwork. Although expensive, it is worth giving UV protective glass some serious consideration, especially for paintings with high monetary or sentimental value.

Final Thoughts

When deciding whether to frame your artwork behind glass, the main factor that will affect your decision will the medium used and the surface it has been completed on.

Generally speaking, acrylic and oil paintings on canvas will not require framing behind glass. Especially for oil paintings, which are best left to breathe, glass within the frame could actually hinder the artwork.

Artworks completed on paper will almost certainly require framing behind glass to provide the painting with sufficient barrier protection.

If you have purchased a painting and have any doubts or questions about how to frame it, it is best to get in contact with the vendor or the artist in question, and they can advise on the most suitable method for your individual work of art.