# Utility Knife

Hewn Tool Library · https://hewn.build/tools/utility-knife

Corrected: An independent reviewer read this entry and found corrections. They have been applied to the text, and the reviewer re-checked the correction that mattered most for safety and found it done; the others have not been re-checked yet. The list at the end is the record of what changed.

Cite as: "Utility Knife." Hewn Tool Library, hewn.build/tools/utility-knife. Reviewed 2026-07-31.

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## Identity
- **Name:** Utility knife. Alternate/regional names: **box cutter** / **box knife** (US warehouse and retail usage), **Stanley knife** (British/Commonwealth; a common proprietary eponym for this tool, which dictionaries still label as a trademark, with no trademark-status source supporting legal genericization `[relayed]`), **razor knife** (US trade/construction usage).
- **Family/category:** a compact general-purpose work knife whose cutting element is replaceable, reversible, segmented, retractable, folding, fixed in a replaceable holder, guarded, or concealed, depending on subtype. The familiar retractable trapezoidal-blade knife is the most common form but not the defining mechanism of every variant listed here. Distinct from fixed-blade sheath knives and folding pocket/EDC knives by its renewable blade.
- **One-line:** a hand tool built around a cheap, renewable blade rather than a single fixed edge. The disposability of the blade is the design, not an afterthought. Blade compatibility and safety behavior are model-specific.

## How NOT to use it (the heaviest section)

**Not-for:** prying (screwdriver or pry-bar substitution is a forum-documented cross-tool misuse); twisting, bending, side-loading, striking, or improvising the blade as a scraper unless the exact tool and blade are designed for it; cutting metal (the blade is thin and brittle, unsupported laterally); cutting tensioned strapping; energized electrical work and freehand wire stripping; food preparation; precision veneer and fine paper work.

**Dangerous:** this is a laceration and puncture tool.
- **The cardinal rule.** Keep the cutting stroke, the body and the supporting hand outside the cut path, including the follow-through, "when able" (OSHA-supported knife-blade instructor guide, `[relayed]`). Cut away from the body, as the trade's universal rule; no single OSHA regulation states it verbatim, so it functions as trade consensus.
- **Where the blade is exposed.** Reaching blind into a box interior while cutting, and a blade that fails to lock or retract, are repeatedly cited failure points. **An auto-retracting knife does not guard you while you hold the slider** (see Descendants); verify the blade position afterwards.
- **Open snapping** of a snap-off segment can launch it (see Anatomy); use the snapper or a container, with eye and hand protection.
- **Tensioned strapping.** Cutting it with a utility knife risks a recoiling strap strike and shifting load (see Matching).
- **Electrical.** Do not use a utility knife on energized conductors; a blade can reach a live conductor, and the handle is not insulation (see Matching).
- **Ceramic blades** chip under side load and are brittle; fragment shedding is a hazard in some settings (Slice `[relayed]`).
- **PPE and handling.** Use eye and hand protection chosen for the task and the material, per the manual and a task assessment; PPE does not make a bad cut path safe.
- **Beyond the blade.** Do not leave loose blades in ordinary waste; use a containing disposal method.

**Damaging:** a dull or wrong blade needs more force, which is the condition under which slips happen (OLFA, read in this pass); stop and swap it. Forcing a straight blade into carpet, linoleum or shingle work tends to over-penetrate and gouge the substrate; a hook blade can reduce the likelihood of cutting the substrate when its geometry, exposure and material are suitable, but cannot guarantee it will not gouge, snag or cut beneath. Do not push a dulling blade rather than swapping or snapping it.

**Beginner-trap:** over-extending a blade wastes blade life and increases the exposed edge with no benefit, so use the **minimum exposure needed for the material**, per the model's instructions, and neither add blade as a safety measure nor assume "sharp means safe." Pushing a dulling blade, cutting toward the body or supporting hand, and trusting a retracting mechanism without checking it are the common errors.

**Lineage-misuse:** a general utility knife is not a [[Carpet Knife]] (built Run 312) despite looking similar; trade sources treat conflating them as a real mistake. A drywall/hook-blade variant is not a taping/joint knife, which spreads compound. A hook blade is a single-purpose lineage tool; running it as an everyday straight-cut blade, or a straight blade on jobs a hook blade was built for, is the same error in either direction. Treating a folding knife's closure like a slider-retract lock, or the reverse, misapplies one variant's retention. Do not treat manual, auto-retracting, smart-retracting, guarded and concealed-blade mechanisms as one behavior, and do not assume a nominally similar blade fits another maker's carrier.

## Correct use
**Genuinely good at** light sheet, packaging, scoring and trimming work when the exact blade matches the material.
- **Choose and inspect.** Select the exact knife and blade for the material. Inspect the handle, blade carrier, fasteners, lock, slider, guard and blade before use; remove damaged tools and bent, chipped, loose or incompatible blades from service.
- **Minimum exposure.** Use the minimum blade exposure needed for the material and follow the model's instructions. OLFA's cutter-use page: extend only one blade segment on snap-off cutters.
- **Support and hand position.** Work on a stable surface; secure the material without placing the supporting hand in the cut path; keep the body outside the projected path and the follow-through. OLFA: "Putting your hand in the way of the blade is very dangerous."
- **Straightedge.** Use a thick one and press the blade against its spine, not a thin or sloped ruler that lets the blade ride up (OLFA, read in this pass). A cutting mat protects the surface and the blade where appropriate.
- **Dull or unsuitable blade.** If the cut needs excessive force or leaves poor edges, **stop** and select a fresh, undamaged, compatible blade or a more suitable tool. OLFA: "Using a dull blade requires extra force, which is a cause of injury." **Sharpness does not remove the need to keep every body part out of the cut path**; a sharp blade can still cause a severe cut.
- **Finish.** Retract, close or guard the blade immediately after the cut ("Make sure to retract blade fully when not in use," OLFA), and store the knife securely.
- **Blade change and disposal.** Use the manufacturer's blade-change method. Contain used blades and snap-off segments in a proper disposal device; do not leave loose blades in ordinary waste.

## Matching (the workbench's first read)
- **Strong match** (with the blade and knife type specified for that material): opening cartons without excessive penetration; cutting tape; breaking down clean cardboard; scoring drywall face paper; cutting suitable sheet goods, foam board, vinyl, carpet, roofing material, rope or twine.
- **Materials, split:** score drywall face paper for a controlled break; score only plastics or laminates whose manufacturer specifies that method; slice thin loose veneer with a suitable straightedge and blade; **use a saw for plywood sheet.** Plywood does not generally score-and-snap like gypsum board, and "plywood veneer" is ambiguous between a thin veneer sheet and a face ply.
- **Conditional match:** caulk-nozzle trimming, cable-jacket work, laminate or plastic scoring, and hook-blade roofing or flooring work, only when the product and material instructions support the method and the work can be stabilized with hands clear. Trim laminate edge banding only where the product allows.
- **Packaging band and strapping, defined by material and tension.** The utility knife matches **loose, nonmetallic packaging band only when the exact blade is rated for it.** **Do not cut tensioned steel or plastic strapping with a general utility knife.** Use a purpose-designed strapping cutter and follow the strapping manufacturer's method for controlling recoil, body position, bystanders and load movement. Tensioned strap can recoil, flail and allow a load to shift (Uline's strapping safety guide, which requires a purpose-designed cutter, a safe body position and bystander clearance `[manual, relayed]`).
- **Wire and cable: not a generic utility-knife capability.** "Crude wire-insulation stripping" is **removed** from the matching data. Only use a knife or notch expressly designed by its manufacturer for the cable and conductor range, **on a verified de-energized circuit**, following the electrical work procedure. Prefer a correctly sized wire or cable stripper that controls cut depth and avoids conductor damage. **Never treat a plastic knife handle as electrical insulation.** A blade can nick conductors or the supporting hand. A model-specific notch (for example Klein's self-retracting knife, which has a stripping notch and releases on slider release `[relayed]`) does not validate freehand stripping with any utility blade or any use near live circuits.
- **Do not match:** energized electrical work; freehand generic wire stripping; tensioned strapping; metal cutting; prying; chopping; food preparation with oil-coated industrial blades (OLFA says its blade oil is not food-safe `[relayed]`); plywood sheet score-and-snap; any use requiring substantial lateral blade load; precision veneer or fine paper work, where a dedicated craft/hobby knife wins.
- **Suits:** unboxing/receiving, cardboard breakdown and shop cleanup, drywall install/repair, flooring and carpet installation, cutting foam/insulation board, scoring laminate where the maker specifies it, general packaging.
- **Kit-fit:** pairs with a thick straightedge or speed square for scored straight cuts, a cutting mat, and a blade-disposal container. Substitutes in a pinch for light-duty scissors or a light scoring tool, never for a chisel or saw. Cannot replace a pull saw for thick material, a carpet knife for volume flooring work, or a chisel for wood joinery.
- **Access: beginner-usable with instruction and supervision, but not inherently safe.** A replaceable-blade knife remains capable of deep laceration and puncture, and no short list of rules changes that. Select a model and blade intended for the material; inspect the handle, carrier, lock and blade; support the work on a stable surface; expose only the minimum blade; keep the body and supporting hand outside the cut path; use task-appropriate eye and hand protection; retract or close the blade immediately; and use a blade-change and disposal method that contains the sharp edge. **Safety, auto-retracting and guarded designs reduce particular hazards but do not prevent every cut**; safer-design models are preferred where compatible. Slice itself says its blade can cut skin, and OLFA describes safety models as reducing risk.
- **Revival:** honestly, no. This is a pure consumable-utility tool with essentially no heritage romance. It earns its place on utility, not story. (Editorial, not matching data.)

## Anatomy
Optional features (spare-blade storage, quick release, belt clip, rack-and-pinion advance, rear-cap snapping, multi-position locking) are product features, **not universal anatomy**.
- **Body/handle:** die-cast zinc alloy (the classic Stanley yellow) or reinforced glass-filled nylon; houses the mechanism.
- **Blade-advance slider / thumb-wheel:** moves the blade carrier along a channel; some models use a rack-and-pinion gear for controlled advance.
- **Blade channel/carrier:** the internal carriage and nose piece that cradles the blade and guides it in a straight line.
- **Blade lock:** a single snap-lock position, a ratchet or multi-position lock, a continuous screw adjustment, or none; a quick-release button on some models frees the blade for replacement.
- **Spare-blade storage:** a magazine inside the handle exists on **some** snap-off handles and some standard-blade models; it is model-specific.
- **Snap-off segments and the snapper.** A snap-off blade has one continuous sharpened long edge divided into scored segments. The blade is already scored; a cap notch or a dedicated snapper supplies controlled bending. A rear cap may double as a snapper on some models. **Snap only the scored segment, with one segment exposed, using the model's dedicated snapper or a blade-disposal container that captures the fragment; wear the manufacturer-specified eye and hand protection, and dispose of segments under local rules.** Open snapping can launch a sharp segment. OLFA's beginner instructions call for a dedicated snapper, safety goggles and gloves `[manual, relayed]`. OLFA's cutter-use page, read in this pass, warns of a "risk of unintentional blade snapping if it is exposed in excess."
- **Belt/pocket clip:** a spring clip on some models.
- **Retraction mechanisms:** see Descendants. Manual, auto-retracting, smart-retracting, retractable-guard and concealed-blade designs are distinct and cannot share one description. Do not assume a spring mechanism operated correctly; verify the blade or guard position.
- **The blade.** *Common trapezoid blades* often have a sharpened long edge and **two reversible end points**; edge grind (single or double bevel) varies by product. *Snap-off blades* have a continuous cutting edge divided into scored segments. "Single edge," "single bevel," "two-point" and "double-sided" are not synonyms; hook, rounded-tip, serrated and specialty blades are model-specific. Nominal length, width and thickness do not by themselves make a blade interchangeable (see History).

## Variations (living)
| Variant | What differs | What it's for |
|---|---|---|
| Manual sliding retractable (one lock position) | Blade locks fully out or fully in | General cutting; confirm the lock on the exact model |
| Manual sliding retractable (multi-position or screw-adjust) | Several detents or continuous adjustment | Matching blade-out length to material thickness |
| Auto-retracting knife | Blade retracts when the actuator is released; **may stay exposed while the slider is held** | Reduces some exposure modes; does not prevent every cut |
| Smart-retracting knife | Adds retraction when material contact ends, even with the actuator held (per Slice) | As above; model-specific |
| Concealed-blade cutter | Blade inside a guarded cutting channel | Limits access to the edge; not for every material |
| Spring-loaded blade-guard knife (e.g. US 6,070,326A) | Fixed projecting blade, spring guard | A different mechanism from a retracting carrier |
| Folding utility knife | Closes like a pocketknife | Pocket carry, different retention expectations |
| Snap-off blade knife (OLFA-style) | Segmented blade snapped in increments | Renewing the edge without full blade replacement |
| Fixed-blade utility knife | No retraction, blade in a replaceable holder | Heavy daily use where rigidity is preferred |
| Ceramic-blade safety knife (Slice) | Zirconium-oxide blade, non-conductive, non-magnetic | Cleanroom/electronics work; brittle under side load; not for food/pharma |
| Hook-blade utility knife | Curved hook cutting point | Roofing felt, shingles, carpet, linoleum pull-cuts |
| Scoring/heavy-duty utility knife | Reinforced body, thicker blade | Shingles, thick composite, repeated pull-cuts |
| Disposable/single-use utility knife | Molded plastic body, blade not replaceable | Packaging/warehouse settings |
| Purpose-built cable knife (model-specific) | Some knives have a manufacturer-designed stripping notch with a stated wire range | See Matching; not a generic utility-knife capability |

## Trades (where it appears)
Warehouse and shipping/receiving (the tool's single highest-volume daily-use environment); drywall installation and repair; flooring, carpet, and vinyl installation; roofing (hook-blade variant); general carpentry and shop use; retail stock handling; packaging and logistics broadly.

## Lineage
**Ancestors.** Replaceable razor blades and earlier general-purpose knives are plausible technical context. **Direct descent of the slider-and-channel mechanism from a particular razor or pocketknife lineage was not established.** MoMA's curatorial essay says the form is believed to derive from earlier utility knives and straight razor blades, which is an interpretation, not a documented mechanism genealogy `[relayed]`. The cobbler's/shoe knife and the sailor's rigging knife are functionally analogous fixed-blade trade tools, but no source directly connects either to the modern utility knife; that is a plausible parallel, not a documented descent. **Early primary evidence for a renewable blade is Wright's 1923 patent** (see History), which predates Stanley's 1936 model, so no "first replaceable blade" claim is made for Stanley or for 1936.

**Descendants.** Mechanism terms are kept separate, because they do not share one behavior description:
- **Manual sliding retractable** knives: the user advances and retracts the blade. State whether the model has one lock position, multiple detents, continuous screw adjustment, or no positive lock.
- **Auto-retracting** knives retract the blade when the user releases the actuator. On an ordinary auto-retract knife the blade commonly **stays exposed while the user holds the slider**.
- **Smart-retracting** designs add release after the blade leaves the material, even if the actuator remains held (Slice's manual / auto-retracting / smart-retracting distinction, a manufacturer claim `[relayed]`).
- **Spring-loaded blade guards:** **US 6,070,326A**, "Razor knife with retractable blade guard," Harald Berns, Martor-Argentax E.H. Beermann KG, filed 1999-06-11, granted 2000-06-06, covers a **fixed projecting blade with a spring-loaded retractable guard**, not a spring-retracted blade carrier. Its background section names the failure it addresses (injury from an exposed cutting edge and point) and cites four earlier, inadequate guard designs. It does not support a claim of origin for automatic blade retraction.
- **Concealed-blade** cutters limit access through a guarded cutting channel.
- None of these makes careless handling safe, and the exact manual governs.
- **Ceramic-blade safety knives:** Slice, Inc. (founded 2008, TJ Scimone) pioneered a zirconium-oxide "finger-friendly" category. Sourced only to Slice's own company page, so held at lower confidence. Slice itself acknowledges that its blade can cut skin and that ceramic blades are brittle under side load `[relayed]`.
- **Snap-off blade knives (OLFA-style):** see History.

**Contemporaries / siblings.** Kept separate from the general utility knife; cross-links do not imply interchangeability:
- **[[Carpet Knife]]** (hook or straight blade, pull-cut motion): a close cousin that trade sources treat as a named confusion (see Lineage-Misuse). *Built Run 312; its lineage-misuse section documents a six-way manufacturer/retailer naming collision on where the carpet-knife/utility-knife boundary sits.*
- **Linoleum knife** ("banana knife"): a curved fixed blade cutting by a pulling motion (cited via Wikipedia, sourcing thin).
- **Drywall/hook-blade knife:** a curved-hook utility-knife variant. **Not the same tool as a taping/joint knife**, which is a flat, flexible spreading blade for joint compound (Hyde Tools).
- **Roofing hook-blade knife:** a curved hook that can pull-cut felt or shingle material and reduce the likelihood of cutting the substrate beneath when the hook geometry, exposure and material are appropriate. It is not substrate-proof.

## History (Petroski lens — what failure did each evolution fix?)

**The retractable and renewable blade — a patent chain.**
- **US 1,465,751**, "Knife," Robert Lloyd Wright (Salem, OH), filed 1922-05-09, granted 1923-08-21. Wright's text describes a knife with a "disappearing and renewable" blade built to use **spent razor blades**, clamped without tools, explicitly protecting "the cutting edge of the knife as well as the operator" once retracted. MoMA's curatorial essay is said in the original run to cite it as the box cutter's origin point; the review notes the accessible essay page does not cite Wright's patent, so that link is **not relied on here** `[relayed]`. This is **early primary evidence** for a renewable blade, and "earliest patent located" is a bounded research result, not proof that no earlier patent or object existed.
- **US 2,840,903**, "Razor Blade Cutter," Antone M. Christensen (Seattle), filed 1956-10-01, granted 1958-07-01: a slide-arm mechanism moving a standard single-edge razor blade between exposed and shielded positions, so it could "be carried in the pocket without endangering the user." It cites Wright (1922) and earlier prior art (Ross, 1932; Armstrong, US 2,736,960, priority ~1954). It is one mechanism in the development, not proof of a complete patent lineage.
- **No confirmed inventor exists for the trapezoidal Sheffield-style blade shape itself**, a named gap. Treat any source that attributes it to one inventor with skepticism absent a fetched primary patent.

**The snap-off blade — Yoshio Okada, OLFA, 1956. This is OLFA's company account.** OLFA's history describes it as follows (attributed to OLFA, not independently proven in every anecdotal detail): Okada, working at a printing company in postwar Japan, recalled street shoemakers resharpening broken glass shards to cut shoe soles, and noticed that a chocolate bar snaps cleanly along scored segment lines. He completed a prototype in 1956 in Osaka; commercial sale began April 1959; the company was established as Okada Kogyo Co., Ltd. in 1967 and **renamed OLFA Corporation in 1984** (the original entry said 1972, which OLFA's official history does not support `[relayed]`). A 2015 Woodworker's Journal piece quotes an OLFA brand director; that is a trade article relaying the company's own account, so it corroborates publication history but is **not independent** of OLFA. The "candy wrapper foil" detail circulating elsewhere does not appear in any located source and is not repeated. The "Origami Blade Fracture" backronym is unverified and likely apocryphal; OLFA's etymology is Japanese *oru* (折る, "to break/fold") + *ha* (刃, "blade") → OLHA → OLFA. **No original Japanese patent or utility-model number could be verified**; OLFA's site says Okada "obtained the utility model (later patented)," valid only in Japan, with no locatable number or date. The 59-degree grind and the OLHA-to-OLFA material stay attributed to OLFA.

**No governing blade-size standard was identified.** OLFA's FAQ says that no standard specifies snap-off blade size, and it does not guarantee other makers' compatibility `[relayed]`. A claim citing "ANSI B107.500 and JIS G4401" as governing dimensional standards is a mis-citation (ANSI B107.500 covers pliers and shears; JIS G4401 is a steel-grade specification), kept here only as an example of a mis-citation, not as proof of a universal negative. The **common nominal format** for the snap-in trapezoidal blade is roughly 61 mm × 19 mm × 0.63 mm, per a Stanley 11-911 spec sheet, which establishes that product's dimensions, not universal interchangeability or tolerance. OLFA-style snap-off blades run in width families of 9, 12.5, 18 and 25 mm. **Compatibility must be confirmed against the knife and blade manufacturers**, including hole or notch pattern, carrier engagement, thickness tolerance, tip form and manufacturer approval.

**Stanley's category entry is a separate, unresolved chronology.** MoMA's essay dates Stanley's entry to the 1920s (and dates its pictured object circa 1928); UK retail-trade sources date the "true Stanley knife" to 1936, with Stanley acquiring Sheffield cutler J.A. Chapman in 1937. No primary Stanley Black & Decker company-history document resolved this. It is a company/product chronology, not the invention date of replaceable blades generally.

## Human Side

**The trades that live on it.** Warehouse/shipping-receiving, drywall installation, flooring and carpet laying, roofing, and general carpentry depend on it daily, which is why "what utility knife do you use" is a near-permanent thread on trade forums (ContractorTalk). Flooring and carpet specialists on the same forum describe a passed-down habit of carrying sharpened Personna blades with a pocket stone for carpet work. Drywall tradespeople note the material "gums up a knife" fast and prefer a dedicated knife for drywall. These are forum reports: trade texture, not technical or historical fact.

**Named makers.** Stanley (see History). **Yoshio Okada**: his 59-degree grind angle for the snap-off blade is described in OLFA's account as the de facto standard for that format (a company claim). **Slice, Inc.** (TJ Scimone, 2008): ceramic zirconium-oxide blades, claimed roughly 11x the edge life of steel, non-conductive and non-magnetic, marketed for cleanroom/electronics work and not for food/pharma settings because of a chip-shedding risk. These are manufacturer claims. Sheffield's steel-tooling tradition and Milwaukee Tool's utility-knife line are referenced across trade history, but neither has a founder-level history sourced here; named as a gap.

**The injury record, honestly.** Utility knives can cause serious occupational lacerations. An OSHA accident-investigation record documents a 2022 hospitalized finger laceration after a box cutter slipped `[relayed]`, and OSHA 1910.242 requires employers to keep hand tools in safe condition `[relayed]`. OSHA has no utility-knife-specific standard; a 1976 interpretation addresses sharp-edged hand tools and paper cutters generally and supports attention to physical condition, dull edges and task-dependent PPE `[relayed]`. **The reviewed sources do not establish a reliable national share or average cost specific to utility knives.** The original entry's figures (about one million annual US hand injuries, 63% from knife lacerations, box cutters at about one third of workplace tool injuries, about $40,000 per incident) are **removed**: per the reviewer they trace to safety-industry marketing, not to an accessible primary NSC, OSHA or NIOSH dataset with year, population, denominator, injury definition and cost method. No primary NIOSH report for a "top three" ranking was found.

**The box cutter and September 11, 2001, stated with its qualifications.** Federal records report that the hijackers used knives and possibly box cutters. The 9/11 Commission heard reports of knives on all four flights, with a box cutter specifically indicated in one report, and the exact blade designs were not verified; its working hypothesis included permissible utility or pocket knives. MoMA's essay likewise notes the exact design of the alleged blades was never verified `[relayed]`. Pre-9/11 screening guidance restricted box cutters while permitting some pocket utility knives under four inches, with an acknowledged gap in telling them apart `[relayed]`. After the attacks, TSA's prohibited-items rule was tightened; the current TSA rule is no utility knives in carry-on, with checked baggage permitted if safely wrapped, which does not by itself establish the full post-2001 chronology `[relayed]`. The original entry's claims of a categorical FBI determination (seven knives purchased, none over 3.5 inches) and of a 2013 TSA reversal were not re-checked in this pass and are not repeated as established. Legal carry rules vary by jurisdiction and context and are kept separate from operational matching.

## Proof of existence
- **Patents, fetched and read in the original run:** US 1,465,751 (Wright, filed 1922-05-09, granted 1923-08-21), early primary evidence for a disappearing, renewable blade using spent razor blades; US 2,840,903 (Christensen, filed 1956-10-01, granted 1958-07-01); US 6,070,326A (Berns / Martor-Argentax, filed 1999-06-11, granted 2000-06-06), a spring-loaded blade guard on a fixed blade.
- **Citation-confirmed but not independently fetched:** US 2,736,960 (Armstrong, priority ~1954, granted 1956), cited in the Christensen patent's prior-art discussion.
- **Museum/collection records: not located in the sources and searches consulted** (original run, 2026-07-13). Searches of the Smithsonian NMAH and the UK Science Museum Group collections returned no catalogued utility/box-knife object, which supports only "not found in the search conducted." MoMA's *Design and Violence* essay presents an object dated circa 1928 `[relayed]`.
- **Documentary evidence:** the 9/11 Commission Staff Statement No. 3 and Seventh Public Hearing record, with the qualifications in Human Side `[relayed]`.
- **Company-history record:** OLFA's own history is the most detailed founding account of any modern accessory in this entry, and is attributed to OLFA. A Woodworker's Journal piece relays it and is not independent.

## References
| Title/Source | Author/Org | URL or Number | Kind | Verification |
|---|---|---|---|---|
| US Patent 1,465,751, "Knife" | Robert Lloyd Wright | patents.google.com/patent/US1465751A | patent | read in the original run; confirmed by the reviewer |
| US Patent 2,840,903, "Razor Blade Cutter" | Antone M. Christensen | patents.google.com/patent/US2840903A | patent | read in the original run; confirmed by the reviewer |
| US Patent 2,736,960 | James A. Armstrong | patents.google.com/patent/US2736960A | patent | citation-confirmed only |
| US Patent 6,070,326A, "Razor knife with retractable blade guard" | Harald Berns / Martor-Argentax | patents.google.com/patent/US6070326A | patent | read in the original run; reclassified as a blade guard |
| "Design and Violence: The Box Cutter" | MoMA | moma.org/interactives/exhibitions/2013/designandviolence/the-box-cutter-slash-utility-knife/ | museum essay | curatorial interpretation; relayed |
| "Birth of the OLFA Cutter" / Company History | OLFA Corporation | olfa.co.jp/en/birth_of_olfa_cutter.html; olfa.co.jp/en/company/history.html | company history | attributed company claims; relayed (history page not fetched in the fix pass) |
| "How to Use Cutters Properly" | OLFA | olfa.co.jp/en/howto.html | manufacturer guidance | **read in the 2026-10-16 fix pass** |
| ESK-1 Instruction Manual | OLFA | olfa.co.jp/en/manual.html | manufacturer manual | `[manual, relayed]` |
| FAQ (no snap-off size standard; blade oil not food-safe) | OLFA | olfa.co.jp/en/faq.html | manufacturer | relayed |
| "OLFA: Perfecting Cutting Tools for Over 50 Years" | Woodworker's Journal, 2015 | woodworkersjournal.com | trade press | relays OLFA brand director; not independent |
| Utility blade guide; Safety Blade Storage FAQ | Slice | eu.sliceproducts.com/collections/utility-blades; sliceproducts.com/pages/slice-safety-blades-special-storage | manufacturer | manufacturer claims; relayed |
| Self-Retracting Utility Knife | Klein Tools | kleintools.com/catalog/utility-knives/self-retracting-utility-knife | manufacturer | relayed (a fetch attempt failed) |
| Strapping Hand Tools Safety Guide | Uline | img.uline.com/is/content/uline/RH-24pdf | manufacturer safety guide | `[manual, relayed]` |
| OSHA 1910.242; OSHA 1976-09-15 interpretation | OSHA | osha.gov/laws-regs/regulations/standardnumber/1910/1910.242; osha.gov/laws-regs/standardinterpretations/1976-09-15 | government | relayed |
| OSHA-supported knife/blade instructor guide | OSHA | obis.osha.gov/dte/grant_materials/fy10/sh-20856-10/SHC_Instructor_Guide.pdf | government | relayed |
| OSHA box-cutter accident record (2022) | OSHA | osha.gov/ords/imis/accidentsearch.accident_detail?id=143384.015 | government | relayed |
| National Safety Council, Prevent Hand Lacerations | NSC | nsc.org/workplace/get-involved/divisions/construction-safety-resources/prevent-hand-lacerations | safety industry | does not support the removed statistics |
| 9/11 Commission Staff Statement No. 3; Seventh Public Hearing | National Commission on Terrorist Attacks | govinfo.library.unt.edu | government | relayed |
| TSA, Utility Knives | TSA | tsa.gov/travel/security-screening/whatcanibring/items/utility-knivesknife | government | relayed |
| Stanley Knife | Cambridge Dictionary | dictionary.cambridge.org/us/dictionary/english/stanley-knife | dictionary | still labels a UK trademark; relayed |
| ContractorTalk, "What utility knife do you use?" and related threads | forum posters | contractortalk.com | forum | trade texture only |
| "Ultimate Carpet Knife Guide" | FamilyHandyman | familyhandyman.com | trade press | secondary |
| Blade-size / spec pages | Stanley, OLFA, DeWalt, Fulgent Tools, Slice | manufacturer sites | manufacturer spec | as in the original run |
| "ANSI B107.500 / JIS G4401" blade-standard claim | vendor blogs | — | vendor blog | misattributed; kept as a mis-citation example |

## The reviewer's corrections (16)

- `BLOCKER` — 1. — Exact claim: “Access: genuinely beginner-safe with three guidance points,” with auto-retract and ceramic models said to “lower the injury ceiling further.”
- `BLOCKER` — 2. — Exact claim: “Auto-retracting safety knives — the blade snaps back into the housing the instant cutting pressure releases, so it can never be left exposed by accident,” supported by US 6,070,326A.
- `BLOCKER` — 3. — Exact claim: Matching includes “crude wire-insulation stripping,” while the not-for section prohibits “cutting wire, strapping, or anything metal.”
- `BLOCKER` — 4. — Exact claim: The tool “cuts … strapping,” without consistently distinguishing material or stored tension; the not-for section says not to cut strapping.
- `SHOULD-FIX` — 5. — Exact claim: “No tool with a genuinely swappable blade predates the 20th century in any source located this run; the first documented replaceable-blade design is Stanley's 1936 model.”
- `SHOULD-FIX` — 6. — Exact claim: Straight razors and folding pocketknives are “the mechanical ancestors most sources point to,” and “the slider-and-channel mechanism … descend[s] from razor and pocketknife hardware.”
- `SHOULD-FIX` — 7. — Exact claim: OLFA was “renamed OLFA Corporation in 1972.”
- `SHOULD-FIX` — 8. — Exact claim: The anatomy says standard trapezoidal blades are “single-bevel,” while “double-sided/two-point (sharpened on both ends)” describes “many snap-off blades.”
- `SHOULD-FIX` — 9. — Exact claim: A rear-cap notch or snapper “scores and cleanly breaks off” a snap-off segment, and spare-blade storage is said to be common on both snap-off and standard-blade models.
- `SHOULD-FIX` — 10. — Exact claim: “No codified blade-dimension standard exists,” followed by “Standard worldwide dimension” and “universal” for a roughly 61 × 19 × 0.63 mm trapezoidal blade.
- `SHOULD-FIX` — 11. — Exact claim: “score-and-snap drywall/plywood veneer/laminate/thin plastic,” plus the claim that a hook blade's confined point “can't plunge past” the target material.
- `SHOULD-FIX` — 12. — Exact claim: “Under-extending forces repeated shallow passes, which raises slip risk rather than lowering it,” and “a sharp knife is a safer knife.”
- `SHOULD-FIX` — 13. — Exact claim: “The injury record — the best-documented human-side thread this corpus has for any tool,” followed by roughly one million annual US hand injuries, 63% from knife lacerations, box cutters causing roughly one-third of workplace tool injuries, and an average incident cost near $40,000.
- `SHOULD-FIX` — 14. — Exact claim: “Box cutters and small knives were the weapons the September 11, 2001 hijackers carried aboard,” with a categorical FBI determination and a claim that the tool's role is fully documented.
- `SHOULD-FIX` — 15. — Exact claim: The OLFA account is said to be “independently corroborated” by a Woodworker's Journal article quoting an OLFA brand director, and the overall confidence is MEDIUM-HIGH partly on that basis.
- `MINOR` — 16. — Exact claim: “Stanley knife … a genericized trademark, confirmed by a live OED entry.”