Key Framing Terms
Kerf
The width of material removed by each saw blade cut, typically 0.125 inches (1/8"). Kerf adds up across many cuts on the same stick and must be accounted for in cut planning to avoid short pieces. See the calculator to factor kerf into your estimates.
Rabbet
The inside edge groove of a moulding where glass, matboard, and artwork components sit. Rabbet depth determines how much material can fit in the frame. This differs from point-to-point measurement, which measures the outer edge. See how RailChop handles rabbet depth in optimization.
Moulding Profile
The cross-sectional shape of the frame moulding — the design determining its appearance from above and structural properties. Each profile has a unique design (rounded, beveled, stepped, etc.) and rabbet depth that affects the final frame appearance and how components fit. Profiles are the foundation of every cut plan.
Remnant
A usable leftover piece of moulding after cutting frames. Instead of discarding short pieces, framers save and catalog them for future jobs, reducing waste and material costs. Most shops waste 15–25% of moulding; tracking and reusing remnants can cut that roughly in half.
Stock Length
Standard lengths moulding is purchased in from suppliers — typically 96", 120", or 144". Knowing your standard stock lengths is essential for optimization, as the optimizer packs your cuts across these sticks to minimize waste.
Allowance
Extra clearance added per cut to ensure the frame opening is slightly larger than the artwork. A typical allowance is 0.125 inches (1/8") per side, though some shops use 0.0625 inches (1/16"). Allowance prevents the frame from being too tight around the glass package. Account for it in the calculator.
Mat Opening
The window cut in matboard where artwork is visible. Mat openings require precise measurement and cutting. The mat opening size, combined with rabbet depth and moulding width, determines the overall framed dimensions.
Optical Center
The perceived visual center of a matted frame. The mat bottom is typically cut slightly larger than the top (by ~10% of the mat height) so the frame feels balanced. This optical adjustment accounts for how the human eye perceives vertical space.
Point-to-Point
An outside-edge measurement of the frame, from one corner point to the opposite corner point. This differs from rabbet measurement, which measures to the inner groove. RailChop optimizes based on the actual cut lengths your frame requires.
Cut Arrangement
The general challenge of laying out a set of required cuts across a set of available stock lengths so that as little material as possible is left over. For multi-order batches with mixed stock and remnants on the rack, the number of possible arrangements grows fast — fast enough that software starts to matter.
Optimization (Cut Planning)
Working out the most efficient way to fit a list of required cuts onto your available sticks and remnants. A solid cut plan reduces waste, leaves usable remnants where possible, and accounts for kerf and miter allowance in every cut. See how cut optimization works.
Cost Per Foot
How moulding suppliers price their products — a per-foot cost applied to your total purchase length. Understanding cost per foot helps you calculate material expenses and justify investment in optimization, which reduces the amount of moulding you need to buy.
True Production Cost
The effective cost of moulding including waste overhead. A $20/ft moulding that generates 20% waste has a true production cost of $25/ft. RailChop's dashboard tracks true production cost per profile, showing the real impact of optimization and remnant reuse on your bottom line.
Cut Ticket
The printed or digital list of cuts for the saw operator, specifying which moulding profile, dimensions, and order each cut belongs to. A well-organized cut ticket minimizes setup time and cutting errors by grouping cuts efficiently across standard-length sticks.
Chop Service
A moulding supply service where the vendor cuts the moulding to your specified dimensions and ships the finished pieces, rather than shipping full sticks. Useful for shops without their own saw, or for one-off frames in mouldings not stocked in-house. Typically more expensive per foot than buying sticks, but eliminates waste.
Length Service
Moulding shipped in standard-length sticks (typically 96", 120", or 144") for the shop to cut in-house. Cheaper per foot than chop service but requires equipment, labor, and creates waste. The standard model for production and mid-volume custom shops.
Join Service
A service where the vendor delivers pre-cut, pre-joined frame corners (usually as a complete frame, ready to fit with glass and artwork). Common for high-volume production orders and shops that don't want to V-nail in-house. More expensive than chop+length but saves labor.
V-Nail
A V-shaped metal fastener pressed into the back of a frame's mitered corners by an underpinner. Holds the joint rigid. The standard joining method for picture frames since the 1970s, replacing older nail-and-glue techniques. Come in different lengths and gauges for different moulding hardness and thickness.
Stacking
Combining two or more mouldings on a single frame — for example, an inner fillet around the artwork with an outer decorative moulding. Creates depth and design flexibility but doubles the cutting work and requires careful rabbet-depth compatibility between layers.
Lip (Rabbet Lip)
The visible front edge of the rabbet — the narrow strip of moulding that overlaps the mat or artwork from the front. A deeper lip shows more moulding over the image; a minimal lip shows less. The lip width is a design choice that affects the overall look of the frame.
Miter
A 45-degree angled cut used to join two pieces of moulding at a 90-degree corner. Four miters produce a standard rectangular frame. Miter accuracy — the angle being exactly 45 degrees — is critical; even small errors compound across four corners and produce visible gaps.
Miter Saw
The powered saw used to cut picture frame moulding at a 45-degree angle. Single miter saws make one cut at a time; double miter saws cut both ends of a piece simultaneously. Blade tooth count and kerf thickness significantly affect cut quality.
Double Miter Saw
A specialized saw with two blades set at opposite 45-degree angles. Both ends of a moulding piece are cut in one operation, dramatically speeding up production. Standard equipment in high-volume production shops; optional upgrade for custom shops cutting more than 30 frames per day.
Linear Foot
The standard unit for pricing and measuring moulding — one foot of length regardless of moulding width or profile. Moulding catalogs quote prices in dollars per linear foot. See the moulding cost calculator for per-frame cost math.
Closed Corner
A frame with finished corners that conceal the miter joint — typically via applied ornament, gilding, or carved detail. Closed-corner frames require careful miter work because the decorative detail must align across the joint. Standard for fine art and museum framing.
Open Corner
A frame where the miter joint is visible in the finished frame. Most contemporary and production frames use open corners — the joint is simply the mitered edge, sanded and finished. Faster to produce than closed corners and suits modern and minimalist mouldings.
Rail
One of the four pieces of moulding that form a frame. The top and bottom rails are horizontal; the side rails are vertical. Useful vocabulary when labeling pieces after cutting — "top rail, bottom rail, left rail, right rail" — to prevent mixups during joining.
Chopper
A manual (non-powered) picture framing tool that cuts moulding by pressing a blade through the material via a lever mechanism. Produces a clean shear cut with effectively zero kerf, but is slower than a powered saw. Still used in some traditional shops for delicate mouldings where tear-out is a concern.
Underpinner
The machine that drives V-nails into the back of a frame's mitered corners. Holds the two rails in position at 90 degrees while firing a V-nail across the joint. Standard equipment in any production or custom framing shop.
Shadow Box
A deep frame that accommodates three-dimensional objects behind the glass — memorabilia, textiles, medals, etc. Requires moulding with a deep rabbet (typically 1.5"+) and spacer strips to hold the glass away from the objects. More complex to build than a standard flat frame.
Spacer
A thin strip (typically 1/16" to 1/4" thick) placed between the glass and the artwork to prevent the two from touching. Prevents condensation damage, mat buckling, and artwork adhering to glass over time. Standard in conservation framing and required for any artwork that shouldn't contact glazing directly.
Fillet
A narrow decorative moulding placed inside a larger frame, typically around the mat opening. Adds visual complexity and depth. Fillets are usually 1/4" to 3/4" wide and work as a design element rather than a structural frame. Sometimes called "liner" or "slip" depending on the specific application.
United Inches (UI)
The sum of a frame's width and height (both in inches). A 16×20 frame is 36 UI. The universal sizing and pricing metric in framing because material cost correlates with perimeter, not area. See the united inch calculator.
Stretched Canvas
A canvas painting mounted on stretcher bars rather than framed. Not a frame in the traditional sense, but often framed secondarily with a simple moulding or float frame. The stretcher bars themselves use different math from picture frame moulding — no mitered corners, interlocking joints instead.
Gallery Wrap
A stretched canvas with the image continuing around the edges so the sides of the canvas are part of the finished look. No frame is added — the canvas is the presentation. Common for contemporary art. If a gallery wrap is eventually framed, it usually gets a float frame.
Float Frame
A frame that holds artwork (usually a canvas) with a visible gap between the artwork edge and the frame inner edge — the artwork appears to "float" within the frame. Doesn't use a rabbet to hold the artwork; instead, the canvas is mounted to the back of the frame. Popular for gallery wraps and contemporary presentation.
Gilding
The application of gold or metal leaf to a frame moulding. Traditional gilding uses real gold leaf laid over a gesso and bole base; modern gilded mouldings often use composition leaf or metallic paint to achieve similar looks at lower cost. Gilded mouldings are more expensive and require careful handling to avoid scratching the finish during cutting and joining.
Conservation Glass
Picture framing glass with UV-blocking coating that filters 97%+ of ultraviolet light, protecting artwork from fading. Clearer than standard glass but more expensive. Standard for any artwork of sentimental or financial value. Standard thickness is 2.0mm, same as non-conservation glass.
Museum Glass
Picture framing glass combining UV protection with anti-reflective coating. The premium glazing option — virtually invisible when properly lit and fully protective against UV fading. Roughly 3–5x the cost of conservation glass, so used primarily for high-value original artwork.
Sight Size
The visible opening of a frame — the dimension where the artwork or mat is visible once the frame is assembled. Equivalent to the rabbet measurement minus a small overlap. Used in quoting and customer communication: "what's the sight size?" means "how much of the artwork shows?"
Related Resources
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