What Exactly Is a Picture Mount?
A picture mount (also called a mat or matboard) is a flat piece of card with a window cut into it. It sits between your artwork and the glass inside a picture frame, creating a border around the image. The window — called the aperture — is cut at a precise 45-degree angle, producing a neat bevelled edge that draws the eye inward towards your picture.
The anatomy of a framed picture — glass, mount, artwork and backing board all sit within the frame
Mounts are typically 1.4mm thick and made from specially manufactured mountboard. The best mounts use conservation-grade board — acid-free, with a white core that won't yellow or discolour over time. This matters because cheaper boards with cream or ivory cores can eventually bleed acids into your artwork, causing foxing and staining that is impossible to reverse.
The mount is placed on top of your artwork inside the frame, holding it flat and keeping it separated from the glass. That separation is more important than most people realise — and it's one of the key reasons every professional framer will recommend using a mount.
Why Use a Picture Mount?
A mount isn't just decoration. It serves four practical purposes that protect your artwork and dramatically improve how it looks on the wall. Here's what a mount does for you:
Protects Your Artwork
The mount creates an air gap between the glass and your image. Without it, condensation can form on the glass and transfer directly onto your print, causing moisture damage, mould, and permanent staining. For delicate media like pastels, charcoal, or watercolours, contact with glass can physically lift pigment off the surface.
Enhances the Presentation
A mount gives your image breathing space. It provides a visual border that separates the artwork from the frame, letting the eye settle on the picture rather than being distracted by the frame edge. Even a simple white mount can transform a print from looking like a snapshot into something gallery-worthy.
Flexible Sizing
Already have a frame but your print doesn't quite fit? A custom-cut mount bridges the gap perfectly. You can frame an A4 print inside a much larger frame, with the mount filling the space between. This gives you total flexibility — no trimming your artwork or buying a new frame.
Long-Term Preservation
Conservation-grade mounts are pH neutral, acid-free, and designed not to deteriorate. They actively protect your artwork from chemical damage caused by acidic backing boards. If you're framing anything with sentimental or monetary value, a quality mount is essential insurance.
White mounts give each piece breathing space and a polished, gallery-quality appearance
The Difference a Mount Makes
The easiest way to understand the value of a picture mount is to see the difference side by side. Here's what changes when you add a mount to a framed piece:
- Image sits directly against the glass
- Condensation can damage the print
- Artwork looks cramped in the frame
- No separation between image and frame edge
- Pastels and charcoal can smudge on glass
- Looks amateur and unfinished
- Air gap protects the image from glass
- No moisture transfer or mould risk
- Artwork has room to breathe visually
- Clean bevelled border draws the eye inward
- Delicate media stays untouched
- Professional, gallery-quality finish
Types of Picture Mount
Not all mounts are the same. Depending on what you're framing and the look you want to achieve, there are several types to consider:
Single Mount
The most common type. One layer of mountboard with a single bevelled aperture. A single mount in white or off-white works beautifully for the vast majority of prints, photographs, and artwork. It's clean, versatile, and timeless.
Double Mount
Two layers of mountboard stacked together, with the bottom layer slightly visible around the aperture edge. This creates a thin inner border — often in a contrasting colour — that adds depth and elegance. Double mounts are popular for wedding photographs, limited-edition prints, and pieces where you want a more premium feel.
Multi-Aperture Mount
A mount with more than one window cut into it, allowing you to display multiple images in a single frame. Multi-aperture mounts are ideal for photo collages, wedding collections, baby milestone photographs, or any group of related images you want presented together.
Designing a multi-aperture mount used to mean sending diagrams by email and waiting for a quote. At Rondo Arts, you can design your own multi-aperture layout online using our interactive design tool — positioning each aperture exactly where you want it with a live preview of the result.
A multi-aperture mount lets you display multiple photographs beautifully in one frame
Conservation & Museum Grade
Standard conservation-grade mountboard (1.4mm, white core, acid-free) is suitable for the vast majority of framing. For particularly valuable original artwork, museum-grade boards are available — these are 100% cotton rag, completely free of wood pulp, and offer the highest possible level of protection. Most photographs, prints, and reproductions are perfectly served by conservation-grade board.
Choosing the Right Mount
Colour
White and off-white are the most popular mount colours, and for good reason — they complement almost everything. But a carefully chosen colour can make a real difference. A mount that picks up a subtle tone from within the artwork creates a cohesive, intentional look. As a rule of thumb: lighter mounts open up the artwork and create a spacious feel, while darker mounts draw focus inward and add drama.
Our mountboard range — over 20 colours to complement any artwork
Border Width
The width of the border around your image is mostly a matter of taste, but there are some guidelines. A border that's too narrow looks cramped and rushed; too wide can overwhelm smaller images. As a starting point, 50–70mm borders work well for medium prints. For smaller images (say A5 or 6×4"), consider wider borders to give the piece presence on the wall. Larger images can work with narrower borders.
Size
Your mount needs to fit both your frame and your artwork. The outer dimensions match the inside of your frame, and the aperture dimensions should be slightly smaller than your image (typically 3mm smaller on each side) so the mount overlaps the edges and holds the picture in place. If you're not sure about measurements, our design tool shows you a scaled preview of exactly what your finished mount will look like before you order.
Why Custom Mounts Beat Off-the-Shelf
You can buy pre-cut mounts in standard sizes from craft shops, and they'll do a job. But there are several reasons why a custom-cut mount is worth the small extra investment:
Exact fit. A custom mount is cut to your precise measurements — your frame size, your artwork size, your preferred border widths. No compromising, no trimming your artwork, no frames that don't quite fit.
Any aperture shape or position. Standard mounts are centred with equal borders. A custom mount lets you adjust the borders individually — for example, a slightly wider bottom border (called a "weighted" mount) is a classic technique that makes the artwork look perfectly balanced rather than visually sinking.
Multiple apertures. Off-the-shelf multi-aperture mounts come in a handful of fixed layouts. A custom mount lets you design exactly the layout you need — any number of windows, any sizes, any positions.
Professional bevel cut. Every custom mount from Rondo Arts is precision-cut by computerised equipment with a clean 45-degree bevel. The bevel catches the light beautifully and gives a crisp, professional finish that you simply can't achieve with a hand-held craft knife.
Our interactive design tool — design your mount online with a live scaled preview
Ready to Design Your Mount?
Use our free interactive design tool to create your perfect picture mount — choose your size, colour, and aperture layout with a live preview before you order.
Open the Design Tool →Whether you're framing a treasured family photograph, preparing prints for exhibition, or simply refreshing how your artwork looks on the wall, a well-chosen picture mount makes all the difference. It protects what matters and presents it at its best.
Need help choosing? Get in touch — we're always happy to advise on sizes, colours, and mount types for your specific project. Or jump straight into our design tool and see for yourself.