Utility knife

How it works

The user draws the exposed edge of the blade across the material. Stanley’s 1940 catalog describes the No. 199 as a razor-edge tool for trimming and cutting fibre insulating board, cardboard, leather, gaskets, rubber, veneer and open cartons, and OLFA advises cutting on a cutting mat and, when ruling a line, along the back side of a thick straightedge.

Two blade systems are in common use. In the first, a fixed-shape blade is held in a handle and replaced when dull; the Stanley 99E retains a blade in a metal handle with the blade sliding to three positions, according to Stanley’s US page, and holds spare blades inside. In the second, the blade has score lines across it so that a dull end can be snapped off to expose a fresh edge. OLFA says its inventor made the blade with lines ahead of time so that, like a chocolate bar, it could be broken off when it stopped cutting.

Anatomy

Handle: Die-cast zinc on the Stanley 99E, which Stanley says is both strong and light; the 1940 and 1949 Stanley No. 199 was cast aluminum.
Blade: A thin steel strip with a cutting edge, available in regular and heavy-duty thickness in Stanley’s catalogs.
Nose or blade clamp: Stanley says the interlocking nose of the 99E secures the blade for accurate cuts.
Slide or thumb button: Moves the blade out and back on retractable models.
Blade storage: Spare blades kept inside the handle; five in the 1949 No. 199 and up to ten in the current 99E, according to Stanley.

Variants

Fixed handle with blades stored inside: Stanley No. 199 (1940) and Nos. 199 and 299 (1949 and 1958 catalogs), razor-edge knives with extra blades kept in the handle.
Retractable-blade knife: The blade slides into and out of the handle; Stanley says its 99E is its original retractable utility knife since 1952.
Snap-off blade knife: Invented by Yoshio Okada in 1956 and sold by his company, OLFA, from 1959 according to the company.
Carbide-tipped blade: Stanley’s 1958 catalog lists a carbide-tipped blade for the No. 199 for score-cutting asphalt products, abrasive composition siding and roofing materials.

Specifications

Blade thickness, regular · in: 0.017Stanley catalog No. 1991 blade, 1949.
Blade thickness, heavy duty · in: 0.025Stanley catalog No. 1992 blade, 1949.
Handle length · in: 6Stanley No. 199, 1940 and 1949, and the current 99E.
Blade positions, 99E · count: Stanley’s US page says 3 positions and its Australian page says 5.
Snap-off blade angle · degrees: 59OLFA says the 59-degree angle was found in its prototyping and has been kept.

Made to

OSHA 29-CFR-1910-242

Safety and care

Safety

OLFA’s guidance is to keep the hand that holds the material out of the path of the blade, work on a stable flat surface, avoid excess force, avoid awkward postures, retract the blade fully when not cutting and store the knife out of the reach of small children.
OLFA says to check a knife before use for a chipped blade or broken body, and not to use a knife when unwell or unable to concentrate.
OSHA 3080 directs that knives be pointed away from aisles and from other workers, and 29 CFR 1910.242 makes the employer responsible for the safe condition of hand tools.

Care

Replace or snap off a dull blade; OSHA 3080 states that knives must be sharp and that dull tools can cause more hazards than sharp ones.

Tips

Extend only one segment of a snap-off blade
OLFA’s guidance is that the blade should be extended by about one score line. A longer exposed blade can break unexpectedly, which is dangerous.1
Snap off or change the blade as soon as it drags
OLFA says a dull blade takes more force, which is a cause of injury, and should be snapped off or replaced. If heavy force is needed, the blade is dull or the material is unsuited to a knife.1
Cut on a cutting mat
OLFA says that without a mat the blade can go through and mark the table, chip, or dull quickly.1
Cut against the back of a thick straightedge
OLFA’s advice is to use a thick rule and put the blade against its back (vertical) side. A thin rule or a sloped side lets the knife ride up over the edge, which can injure the user.1
Use the heavy-duty blade for dense materials
Stanley sold a regular blade (No. 1991) and a heavy-duty blade (No. 1992) for the same knife, the latter 0.025 inch thick against 0.017 inch, and its 1958 catalog lists a carbide-tipped blade (No. 1995) for score-cutting asphalt products, abrasive composition siding and roofing materials.1 2 3
Keep spare blades in the handle
Stanley’s catalogs describe the No. 199 as keeping extra blades in the handle, and Stanley says the current 99E stores up to ten.1 2

History

Earliest documented

1 October 1940 (earliest dated primary source located)

United States (The Stanley Works)

The Stanley Works catalog No. 50, dated 1 October 1940, lists the No. 199 knife with six blades as a razor-edge tool for trimming and cutting fibre insulating board and also cardboard, leather, asbestos, gaskets, auto top and upholstery materials, rubber, veneer and open cartons. It is made of cast aluminum and extra blades are kept in the handle. Stanley and other sources claim earlier or later dates for the retractable No. 99 (see disputed).1

The utility knife is a holder for a replaceable razor-type blade. Gillette’s 1904 patent explains the basis: a thin blade in a holder can be replaced with a sharp one instead of being honed. Stanley’s catalogs of 1940 and 1949 describe the knife in those terms, as a razor-edge tool taking pointed razor-type blades, and list the work: board, cardboard, leather, gaskets, upholstery and open cartons.

Stanley’s own catalogs show the form changing slowly. The 1940 No. 199 is a cast-aluminum handle with extra blades inside. In 1949 a lighter perforated No. 299 is added and both are headed Utility Knives. By 1958 a blade guard is packed with each knife and a carbide-tipped blade is offered for roofing and siding materials. Stanley’s current page names the 99E as its original retractable knife since 1952, with a die-cast zinc body; the catalogs read here do not show a retractable model, so the date rests on Stanley’s statement.

The snap-off blade solved a separate problem. OLFA’s account is that Japanese printing shops of the time cut paper with razor blades gripped between the fingers, which was dangerous, and discarded the blade when the edge dulled. Okada, drawing on shoemakers’ habit of breaking glass for a fresh edge and on a chocolate bar, made a blade with score lines so that a dull end could be snapped off. He found, OLFA says, a blade angle of 59 degrees. Manufacturers he approached declined, and he had 3000 pressed himself and corrected them by hand over three months.

Safety guidance has grown with the tool. OLFA’s guidance covers blade extension, the use of a mat and a thick straightedge, and storage. It states that its yellow color, adopted in 1967, was chosen to make the knife conspicuous in a tool box so that people would not be hurt by it unexpectedly; this is the company’s own account. OSHA’s hand-tool guide says that knives must be sharp because dull tools cause more hazards than sharp ones.

The tool is widely used across the trades. O*NET’s Tools Used table lists utility knives for 16 of the 17 occupations mapped to this tool in the archive’s crosswalk, and also lists roofing, masonry, trimming and angle knives as separate tools.

Timeline

1904
King C. Gillette’s US Patent 775,134 (filed 1901) describes a razor with thin blades held in a holder, so that a dull blade is readily replaced with a sharp one without honing.1
1940
Stanley’s catalog No. 50 (1 October) lists the No. 199 knife with six blades at $1.50, with regular (No. 1991) and heavy-duty (No. 1992) extra blades.1
1949
Stanley’s catalog No. 34 lists Nos. 199 and 299 as “Stanley Utility Knives”: the 199 of cast aluminum and the 299 perforated for lightness, each furnished with five blades in the handle.1
1952
Stanley says that the 99E is its original retractable utility knife “since 1952”.1 2
1956
Yoshio Okada, working at a printing shop in Japan, completes a prototype of a knife with a blade scored for snapping, about 13 cm long and 1 cm wide with score lines about 5 mm apart, according to OLFA.1 2
1958
Stanley’s catalog No. 34 lists the No. 199 and No. 299 with a protective blade guard packed with each knife and a carbide-tipped blade (No. 1995).1
1959
OLFA’s company history records that the snap-off cutter was commercialized and put on sale in April 1959; its birth story says the first commercial product was a batch of 3000 knives that Okada pressed and corrected by hand.1 2
1967
Okada founds Okada Kogyo (later OLFA) on 8 June, and OLFA’s A and L types, sold from 1967, first use the yellow color.1

Where the sources disagree

When did Stanley introduce its utility knife and its retractable No. 99?

Stanley’s original retractable utility knife, the 99E, dates from 1952.1 2
Stanley Tools (US and Australian product pages)
Stanley Works is said to have invented the utility knife in 1936; the author calls the current Classic 99 a re-release of earlier designs.1
Silodrome (secondary, hedged with “said to”)
The utility knives listed in Stanley’s catalogs of 1940, 1949 and 1958 are the No. 199 and No. 299 with blades stored in the handle; a text search of these catalogs and the 1953 edition found no No. 99 knife.1 2 3 4
Stanley catalogs read for this entry (negative finding from OCR text)

Gaps in the record (5)

The 1936 Stanley date has not been confirmed in any primary source; no Stanley patent or catalog of that year has been located.
No Stanley patent for the No. 99 or the No. 199 has been located.
The first catalog to list the No. 99 has not been identified; the OCR text of four catalogs may omit pages.
The origin of the trapezoidal utility blade shape has not been sourced.
No injury or recall data for utility knives has been located, so no quality or safety comparison is made.