How to Stop Mildew Growing on Photo Frames in Singapore

Created by: PrintForFun. Reviewed and updated by the KT Colour team, October 2026.

The short answer: mildew is a surface mould that loves Singapore's warm, damp air and grows on wood, paper and the dust that settles behind frames. Wipe it off with a mild washing soda or white vinegar solution, dry the frame fully, and keep it away for good with airflow, a dehumidifier or silica gel. A mildewed mat board is the one thing worth replacing rather than cleaning.

If you have found mould (spelled mold in the US) behind a picture frame or on the back of one, this is almost always what it is.

Take down a frame that has hung on the same wall for a few years and you will often find grey or black speckles on the back, the inside of the frame, or the white mat around the photo. It is not dirt and it is not the print failing. It is mildew, and in a climate that sits at 80 percent humidity most of the year it is close to normal. The good news is that it is far easier to deal with than the mould that grows on food.

What mildew is

Mildew is a type of mould that grows flat on a surface rather than into it. It likes warmth, moisture and something organic to feed on: wood, paper, card, and the thin layer of dust that collects behind anything hung on a wall. Because it stays on the surface, it wipes off. Mould that has been left for years can go deeper into untreated wood, which is why it pays to check your frames once or twice a year.

Cleaning it off a wooden or metal frame

You need a soft cloth, a second cloth for rinsing, and one of two household solutions:

• Washing soda (sodium carbonate): dissolve about 2.5 tablespoons in a litre of water. You want a mild alkaline solution, not a strong one, so do not add more.
• Distilled white vinegar, used neat on the cloth. Vinegar also kills the musty smell.

Take the print out of the frame first. Wipe the frame gently with the damp cloth, then wipe again with plain water, then let it dry completely before you put anything back in. Repeat if any marks remain. Do not soak a wooden frame; a damp cloth is enough, and standing water will swell the wood and lift the finish.

Cleaning acrylic and glass

Mildew can grow on the inside face of the acrylic or glass, where moisture gets trapped against the print. Clean it the same way as the frame, with a soft cloth so you do not scratch the acrylic, and dry it fully. Before you reframe anything, wipe the inside of the acrylic with an acrylic cleaner. A clean, dry surface gives mildew nothing to start on.

Mat boards: replace, do not scrub

A mat board is paper, and mildew goes into it rather than sitting on top. Wiping usually spreads the stain and leaves a bigger grey patch than you started with. If a mat has mildew, replace it. We cut mats to any opening size as part of our customised framing service, and a new mat costs far less than the frame.

Is the photo itself safe?

Usually, yes. Mildew tends to start on the back of the frame and the mat before it reaches the print. If there are spots on the photo, do not wipe it with any liquid. Take it out, let it dry, and bring it to us. We can scan it and reprint a clean copy, and for valuable originals our photo restoration service removes the marks digitally. If the original file still exists on your phone or computer, a fresh photo print is the simplest fix.

Four habits that keep mildew away

1. Keep the wall and frame clean. Grease from a kitchen wall and dust behind a frame both feed mildew. Wipe the back of frames when you dust the house.
2. Dry the air. A dehumidifier in a bedroom or study makes the biggest difference. Running the air-conditioner for a few hours a day does the same job in that room.
3. Let air move. Open windows when the weather allows, and leave a small gap behind large frames so moisture does not sit against the wall. Avoid hanging frames on the wall that backs onto a bathroom.
4. Use silica gel. A sachet taped inside the back of a frame, or in the drawer where you store prints, absorbs the moisture that would otherwise start the growth. Keep sachets away from children and pets.

Prevention is cheaper than replacement, but mildew on a frame is not a disaster. Clean it, dry it, and change the conditions that let it grow, and the frame will be fine for years.