I inherited a painting from a relative. It has some cracks so I assume it's oil, not acrylic or watercolor. I also do not know the age, but it is not new.

When I bought a frame to fit it (since it didn't have one), the frame came with a pane of glass.

Will I damage the painting if I place it in the frame behind the glass? (Because I already did. It's been there for a couple of years.) If so, what can I do to mitigate the damage?

There is no visible damage to the painting, I'm just concerned.

  • I don't know the answer but I rarely see oils under glass, so I feel like it may be an issue but I don't know. Another thing that might be worth mentioning is how much space is between the painting and the glass and whether the frame is fully sealed or not. I know they keep some art behind glass but there's a 2-inch or so gap to allow for air.
    – Catija
    Commented Jun 15, 2016 at 16:20
  • 2
    A picture could really help here as someone might recognize certain features in order to give a better answer.
    – Matt
    Commented Jun 15, 2016 at 18:43
  • @Catija It is very common, especially in museums, but they are often of such low reflectivity that it's really hard to discern them (I have the tendency to scrutinize paintings, and am often surprised to find them).
    – Joachim
    Commented Feb 15 at 15:18

4 Answers 4


As long as the Painting isn’t recently painted, within 6-12 months, then there isn’t a general consensus and the answer is: It depends.

The reason for the delay after the painting is finished is that it can take this long for the painting to fully 'dry'. In your case, this isn't a consideration.

One of the biggest threats to your oil painting is the environment: dust, air pollution, UV rays, smoke, pet hair, kids with crayons, red wine splashes. The list is endless. Canvas is porous and if left open to room air, it actually acts like a filter for that air, absorbing chemical and particulate pollution.

Advice from the British Conservation Register on cleaning without glass:

Dust can be removed using a very soft brush with metal elements protected so that they cannot be a cause of damage. Avoid feather dusters, sheep skin dusters, however soft, as they catch. You must be careful to check that there is no paint flaking before dusting. Do not attempt any dusting if the surface appears unstable.

Below is an example of flaking:

Example of flaking

Further examples of flaking can be found on the Painting Conservation Studio website, from where the above image came.

It is much easier to clean the glass or acrylic than to pay for an expert conservator to restore your painting.

If you choose to keep the glass, make sure that the glass is spaced so it does not touch the artwork. A professional picture framer can advise you in this regard, as well as recommend a quality UV protecting glass that will preserve the clarity of the painting.

Further advice from the British Conservation Register on cleaning the glass:

Always spray glass cleaner onto the cloth, not the glass. Spray well away from your painting. The use of backboards is recommended as a preventive conservation measure to protect against the accumulation of dust and dirt, as well as against knocks and accidental damage. A conservator can fit backboards to your paintings for you.

When deciding what to do, ask yourself these questions:

  • Does this canvas artwork hold great sentimental value to me?
  • Am I keeping the artwork to enjoy for a long time?
  • Will I eventually want to resell the artwork?

If the answer is yes to any of these questions, and the work is older than 1 year, then keeping glass will probably be a good long term choice.

  • 2
    As important a reason to not put glass over the oil painting is that it may trap moisture and cause the canvas to rot or paint to separate. Glass is typically not needed for oils -if they are varnished- because the varnish protects the work and allows cleaning. When you see glass over oils at a museum it is probably more about protecting the artwork from humans than anything else.
    – rebusB
    Commented Feb 26, 2019 at 21:31

Believe it or not, oil paintings actually take years to fully dry. It is a good idea to avoid glass on an oil painting the first few years of it's life for that reason. Beyond that, it's perfectly fine to use glass. It does not harm the artwork. However, no matter what you're framing, you should never allow the glass to touch the artwork.

Wikihow actually has a good guide for framing oil paintings with store bought frames: http://m.wikihow.com/Frame-an-Oil-Painting


As long as the painted surface is not in contact with the glass you should be OK. But why leave the glass in, can't you just take it out?

IIRC most of the oils in the Hermitage are under glass - makes them difficult to view properly, but I assume they know what they are doing.

  • Correct, and the the glass guarantees that no one except the museum staff will ever see the paintings again.
    – Cecilio
    Commented Jul 3, 2019 at 1:05

There is no need to frame an oil painting under glass if it's painted on canvas, panel, or board. Glass is used in framing to protect the artwork from moisture and harmful UV rays which can fade the colors. ... If your painting was done on paper or thin card, adding glass to the frame will protect the support.

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