What is the best way to mat a print with a deep frame?

The best way to mat a print with a deep frame is to use an acid-free, four-ply cotton-rag mat with a bevel cut at least 7.5–10 cm (3–4 in) wide, ensuring the print floats centrally within the frame’s rebate depth while maintaining a 1:1.5 to 1:2 ratio between mat width and print margin.

Mat proportions for deep frames

Deep frames—typically 3.8–7.5 cm (1.5–3 in) in rebate depth—require mats proportioned to avoid visual imbalance. The Fine Art Trade Guild recommends a mat width of at least 7.5 cm (3 in) for standard print sizes (e.g., 30x40 cm / 12x16 in) and up to 12.5 cm (5 in) for larger formats (50x70 cm / 20x28 in or A2).

The mat’s inner opening should leave a minimum 1.25–2.5 cm (0.5–1 in) border of the print visible beyond the image area, ensuring no critical details are obscured. For example, a 40x50 cm (16x20 in) print in a 5 cm (2 in) deep frame would use an 8–10 cm (3.25–4 in) mat, maintaining a 1:1.6 ratio between mat width and print margin.

A mat’s width should never exceed the frame’s rebate depth by more than 2.5 cm (1 in), as this creates an optical recession that diminishes the print’s presence.

Material and construction standards

Use 100% cotton-rag mats, 250–310 gsm, with a neutral pH (7–8.5) to meet conservation standards outlined by the American Institute for Conservation. Four-ply thickness (1.4–1.6 mm) provides structural integrity without compressing under glazing. Bevel cuts should angle at 45° to refract light away from the print surface, reducing glare.

Avoid lignin-based or wood-pulp mats, which yellow and degrade over time. For prints exceeding $1,200 in value, consider eight-ply museum-grade mats (3.2 mm thick), though these require frames with a rebate depth of at least 6 cm (2.375 in) to accommodate the additional bulk.

Attachment and spacing techniques

Secure the mat to the print using acid-free hinging tape (e.g., Japanese paper hinges) along the top edge only, allowing for expansion. The print should float 0.3–0.6 cm (0.125–0.25 in) behind the mat’s inner opening to prevent adhesion. For deep frames, use a spacer (e.g., 3 mm polyethylene foam) between the glazing and mat to prevent condensation.

When framing under UV-protective glazing (e.g., 99% UV-blocking acrylic), maintain a 0.5 cm (0.2 in) air gap between the glazing and mat to mitigate moisture buildup. The Canadian Conservation Institute advises against sealing frames hermetically, as this traps humidity and accelerates mold growth.

Color and finish selection

Mat color should complement the print’s dominant tone while maintaining a 10–15% lighter value to avoid competing with the image. For black-and-white prints, use white or off-white mats (e.g., Bright White or Warm White); for color works, opt for neutral grays or soft ivories. Textured finishes (e.g., suede or linen) add depth but require a 1 cm (0.4 in) wider border to offset visual noise.

Avoid colored mats for prints valued above $800, as pigments can fade unevenly under UV exposure. The Tate’s Art Terms glossary notes that overly decorative mats distract from the artwork, particularly in minimalist or contemporary works where the frame’s role is to recede visually.

Framing and installation considerations

Deep frames with mats require precise hanging to maintain optical balance. The print’s center should align with the viewer’s eye level (~145–150 cm / 57–60 in from the floor), with the mat’s width influencing perceived weight. For example, a 60x90 cm (24x36 in) print in a 6 cm (2.375 in) deep frame with a 10 cm (4 in) mat will appear top-heavy if hung above 150 cm (60 in).

When pairing with furniture, adhere to the two-thirds rule: the mat’s bottom edge should sit 15–20 cm (6–8 in) above the object below. For prints in deep shadow-box frames (7.5+ cm / 3+ in), use a French cleat or keyhole hanger to distribute weight—expect framing costs to range from $400–$1,200 for custom work at this scale.

Common questions

How do I calculate mat width for a deep frame?

Measure the frame’s rebate depth (e.g., 5 cm / 2 in) and multiply by 1.5–2 for the mat width (7.5–10 cm / 3–4 in). Ensure the mat’s inner opening leaves a 1.25–2.5 cm (0.5–1 in) border of the print visible beyond the image edge to prevent cropping critical details.

What’s the difference between a bevel and a flat mat cut?

A bevel cut angles the mat’s inner edge at 45°, creating a shadow line that enhances depth. Flat cuts (90°) suit contemporary prints but require precise alignment to avoid a "floating" effect. Bevels are standard for deep frames, as they visually counterbalance the frame’s depth without adding physical weight.

Can I use a deep frame without a mat?

Omitting a mat risks the print adhering to the glazing over time, particularly in humid environments. If foregoing a mat, use a 3–5 mm spacer and ensure the print is hinged to the backing board with acid-free tape. This approach suits ultra-thin frames (≤2 cm / 0.75 in) but compromises long-term conservation.

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