Signs Your Picture Frame Is Damaging Your Artwork

Framing damage happens slowly and behind glass, which is why it is usually found late. Six signs account for most of what we see when an old frame is opened at the workshop: brown discolouration following the line of the mount, scattered rust-coloured spots, rippling in the paper, fading that stops at the rebate line, the artwork adhered to the glazing, and old tape going brittle.

This guide covers what each sign looks like, what caused it, and which ones can be undone. That last question matters more than the other two. Some of this damage stops the moment the frame is opened. Some of it is chemistry that has already finished happening, and no framer can reverse it.

The six signs at a glance

Brown discolouration where the mount sat

This is mount burn, and it is the most common form of framing damage we see. It shows as a tan or brown band following the line of the mount window, usually sharpest along the bevel edge where the board sat closest to the surface. On a print framed forty years ago the band can be several millimetres wide and clearly darker than the paper around it.

The cause is the mount board itself. Wood-pulp board contains lignin, which breaks down over time into acidic compounds. Where the board touches the artwork or sits close to it, those compounds migrate into the paper fibres and darken them. Warmth and humidity speed the process up, so a piece over a radiator or on a cold external wall will show it sooner.

Mount burn cannot be reversed by reframing. The paper has been chemically changed, not dirtied. A paper conservator can sometimes reduce the contrast by washing, but that is conservation treatment with its own risks and cost, and it is worth it on a minority of pieces. What reframing does achieve is stopping it where it is. Acid-free, lignin-free board prevents it entirely, which is why conservation framing specifies cotton museum board or quality alpha-cellulose.

Scattered rust-coloured spots

Foxing shows as small spots, reddish-brown through to yellow-brown, typically a millimetre or two across and sometimes with a soft diffuse edge. It often sits heavier towards the edges of a sheet or concentrated in one corner, which usually points to where the damp was.

Two mechanisms produce it and they frequently run together. One is mould growth, which needs moisture to start. The other is oxidation of metallic particles left in the paper during manufacture, which also needs moisture. Foxing is therefore an environmental problem before it is a framing problem, but a frame that traps damp air against the paper makes it considerably worse. Our guide on condensation inside picture frames covers how moisture gets into a frame package and stays there.

A paper conservator can reduce foxing, sometimes substantially. Nothing sold for the purpose domestically will do it safely. The practical response is to move the piece somewhere stable, have the frame package rebuilt in conservation materials, and accept the spots that remain.

Rippling or waving in the paper

Cockling shows as gentle waves across the sheet, usually running in one direction, most visible when light rakes across the surface rather than hitting it straight on. It is the sign people most often assume is permanent, and it is the one most likely not to be.

Paper takes up and gives off moisture with the room around it, and it changes dimension as it does. If the sheet is restrained it has nowhere to go, so it buckles. The usual culprits are tape along all four edges, a sheet trapped tightly between glazing and backing with no room to move, hinging applied too wet, or a piece framed before it had acclimatised to the room.

Released from restraint and left flat in stable conditions, many sheets relax on their own over weeks. Stubborn cases need controlled humidification and flattening, which is conservator work rather than framing work. The prevention is straightforward: hinge at the top edge only so the sheet can expand and contract freely, leave room inside the mount aperture, and never tape all four sides. Our guide to lacing and hinging covers the mounting methods for works on paper and textile in more detail.

Fading that stops at the rebate line

Fading is difficult to judge on its own, because there is nothing to compare against. The frame supplies the comparison. Lift the mount, or look at the edge of the sheet where the rebate covered it, and you will find a border of stronger colour. That covered strip is close to the original tone. Everything inside it has lost some.

The cause is light exposure, mostly ultraviolet, and the damage is cumulative. Every hour of exposure adds to the total and none of it is reversible. Reds and blues generally go first, which is why hand-coloured maps and older prints drift towards a brown-yellow palette. Standard float glass, the kind supplied in most off-the-shelf frames, blocks only around 45 percent of ultraviolet light and will not prevent this.

Nothing brings faded pigment back. UV-filtering glazing prevents further loss, and position does as much work as glazing does: a piece on a wall that never takes direct sun will outlast the same piece opposite a south-facing window regardless of what is in front of it. Our guide on UV-protective glass for framing sets out the glazing options and where each one is worth specifying.

Artwork stuck to the glazing

This shows as the image adhering to the inside of the glass, often in patches rather than uniformly, sometimes with a faint bloom or cloudiness around the contact area. Photographs are the worst affected, followed by anything with a coated or varnished surface.

The cause is the absence of a gap. If nothing holds the surface of the artwork away from the glazing, repeated cycles of warming and cooling will eventually bond the two together. Photographic emulsion in particular will do this readily, and once it has, the emulsion frequently stays with the glass rather than the print.

Do not attempt to separate them. A conservator may be able to, and may not, but a domestic attempt will take the image off. Bring the piece in with the glass intact so it can be assessed before anything is disturbed. The prevention is a mount, or spacers where the piece is displayed without a mount, so that nothing ever touches the glazing.

Old tape going brittle or leaving stains

You will see yellowed tape at the corners or along the edges, a translucent oily halo in the paper around it, or hard residue where the tape has already released and fallen away.

Pressure-sensitive tape is the cause: masking tape, clear office tape and brown parcel tape all age the same way. The adhesive migrates into the paper and stains it, then the carrier goes brittle and lets go. The important point is that the stain is in the fibres rather than on the surface, so it does not clean off. A conservator can sometimes reduce residue with solvents; the staining is usually permanent.

Reversible hinging avoids the problem entirely. Japanese tissue hinges applied with wheat-starch paste release cleanly with moisture and leave nothing behind, and photo corners hold a sheet without any adhesive touching the artwork at all.

Two more worth checking

• Rust marks from fixings. Older frames commonly have steel pins, staples or brads driven into the rebate to hold the backing. In a damp house these corrode, and the marks come through onto the mount or the artwork in lines and pinpoints matching where the metal sat.

• Insect grazing. Silverfish and some beetles feed on paper and on the starch in older mounts, leaving shallow irregular losses, usually starting at the edges. A properly closed frame package is the defence, which is one of the things a sealed back is for.

What to do if you find any of this

The useful distinction is between stopping the damage and treating the damage. A framer stops it. A paper conservator treats it. Most pieces need the first and only some justify the second.

• Take the piece off the wall and move it somewhere stable: away from external walls, radiators, bathrooms, kitchens and direct sun.

• Leave it closed. Do not open a sealed frame in a damp room, and do not try to lift anything that has stuck to the glazing.

• Photograph it front and back before anything moves, so there is a record of the condition it arrived in.

• Have it looked at before deciding anything. What the piece needs and what it is worth spending are two separate questions, and the second one is yours.

For a good many pieces the sensible answer is to stop the damage, rebuild the frame package in conservation materials, and accept what has already happened. Full conservation treatment can cost more than the framing does, and on a piece of sentimental rather than financial value that is often the wrong trade.

What happens when a damaged piece comes to the workshop

We open the frame and record what is inside before anything is moved, because the old package usually explains the damage. The acidic material then comes out: the old board, the tape, the backing, and any steel fixings in the rebate. Where a hinge has to be removed it is worked with moisture and lifted rather than pulled, so the paper is not torn.

The replacement package is conservation specification: acid-free mount board cut on our Gunnar precision mount cutter, reversible hinging with Japanese tissue and wheat-starch paste, UV-filtering glazing, spacers where the piece is displayed without a mount so nothing contacts the glass, and a sealed back where the piece warrants one. Our conservation framing service covers the specification in full, and our guide to conservation and museum-grade framing explains which of the two tiers a piece needs.

If a piece needs a paper conservator rather than a framer, we say so rather than reframing around the problem. We have been framing since 1974 from the workshop in Bollington, and we are members of the Fine Art Trade Guild and the Museums Association. The framing carries our 5-year guarantee.

How often to check a framed piece

Every couple of years is enough for anything of value, and any time after a house move, a leak, or a change of room. Three checks cover most of it: look along the edge of the image for a rebate line that indicates fading, look at the corners for tape going yellow, and look across the surface in raking light for spots and rippling. Almost everything on this list is visible well before it becomes serious, which is the whole reason for looking. Our guide to protecting heirlooms with conservation framing covers the longer view on pieces meant to be passed on.

If you have found any of these signs on a piece you care about, send us photographs of the front and the back and a note on where it has been hanging, and we will tell you what is stoppable, what is treatable, and what it would cost to rebuild the frame properly.