The P339 Rectangle Barrette: A 1950s Hair Clip Still Worth Wearing

The P339 rectangle barrette measures 5.5 centimetres across and 1.2 centimetres deep, and its straight-edged top plate catches the light in a way that curved clips rarely do. Its defining feature is the twin-coil spring mechanism: two small steel coils sit inside the hollow back plate, pressing a flat tongue against the lower jaw. When you pinch the jaw open, the resistance feels firm but even — a sign of a well-preserved spring rather than a tired one. This precise engineering is what separates the P339 from the more common oval barrettes of the same period, and it is the first thing I check when a reader writes to me about a barrette that will not stay put.

The rectangle shape first appeared in British hair-accessory catalogues in the early 1950s, though it took nearly a decade to catch on. Manufacturers had perfected the oval clip, and retailers were cautious about stocking a shape that did not follow the curve of the head. The P339 was one of the first rectangular barrettes to be produced in quantity, and its success came from a simple insight: a straight barrette holds a section of hair more securely than a curved one, because the flat tongue distributes pressure evenly across the full width of the hair. That even pressure made the P339 a favourite for the sleek, side-swept styles seen on London high streets in the early 1960s.

A Shape That Broke the Rule of Curves

Most mid-century hair accessories followed the natural line of the head. Oval clips, crescent combs and rounded barrettes all echoed the silhouette of a hairstyle, tucking into the curve of a wave or the arc of a roll. The rectangle was a deliberate break from that logic. It sat on top of the hair rather than blending into it, declaring itself as an accessory rather than a hidden fastening. In British fashion magazines of the period, the rectangle barrette was often photographed on models with straight, chin-length hair — the geometric shape echoed the sharp lines of a tailored jacket or a boxy handbag.

The P339's top plate was available in several finishes: a polished silver-tone metal, a dark tortoiseshell effect, and a deep navy enamel that was popular for evening wear. The tortoiseshell version is the one most collectors seek today, because the pattern varies from piece to piece. Each barrette was dipped by hand, and the swirling amber-and-brown mottling means that no two examples are identical. The navy enamel version is rarer, but it tends to chip more easily, so collectors should examine the edges carefully before buying.

In London, the rectangle barrette became associated with the working woman — the secretary, the shop assistant, the junior editor — who needed a hairstyle that would last through a long day. Unlike the elaborate pinned styles of the 1940s, which required regular visits to the hairdresser, a rectangle barrette could be clipped in place in seconds. It was practical, affordable, and modern. The P339 retailed for a modest sum, placing it within reach of most young women, and its clean lines made it acceptable in both the office and the pub after work.

Materials and Construction

The base metal of the P339 is brass, chosen for its strength and its ability to hold a plated finish. The top plate was stamped from a single sheet, then pressed into the rectangular form. The twin-coil spring mechanism was assembled separately and riveted into place — a method that made the barrette easy to repair, because a skilled jeweller could replace the coils without damaging the top plate. This is one of the reasons so many P339 barrettes have survived in working condition, while cheaper clips with integrated springs have long since failed.

The tortoiseshell effect was achieved using a cellulose acetate overlay, a technique common in British accessory manufacturing from the 1930s through the 1960s. Cellulose acetate is a cellulose-derived plastic, and it was prized for its ability to mimic the depth and warmth of real tortoiseshell without using animal products. The overlay was heated and pressed onto the brass base, then polished by hand. Over time, cellulose acetate can develop a slight cloudiness or a faint vinegar-like smell — both are signs of age, and both are treatable with careful cleaning.

Collectors sometimes confuse the P339's cellulose acetate overlay with Bakelite, an earlier plastic that was popular in the 1920s and 1930s. The two materials feel different: Bakelite is heavier and has a distinct phenolic smell, while cellulose acetate is lighter and warmer to the touch. If you are unsure which material you are holding, rub the surface gently with a soft cloth — cellulose acetate produces a faint, sweet odour, while Bakelite produces a sharper, chemical one. The P339 was never made with Bakelite, so the barrette should always have the lighter, warmer feel of cellulose acetate.

The P339 in Detail

What makes the P339 distinct from other rectangle barrettes of its era is the proportion of the top plate. At 5.5 centimetres wide and just 1.2 centimetres deep, it is longer and thinner than most of its competitors. This gives it a delicate, almost architectural appearance on the head, and it allows the barrette to hold a substantial section of hair without feeling bulky. The lower jaw is slightly curved, which helps it grip the hair without creating a hard crease.

There is also a subtle branding detail that collectors look for: the inner edge of the back plate is stamped with the letters "P339" in small, neat type. This stamp is shallow, and on well-worn examples it may be barely visible. A clear stamp is a good sign that the barrette has been handled gently, but it is not the only indicator of quality. The spring tension, the alignment of the top plate, and the condition of the enamel or overlay matter just as much.

Wearing a Rectangle Barrette with a Modern Wardrobe

The P339 was designed for a particular kind of hairstyle — smooth, straight, and sectioned — but it adapts surprisingly well to contemporary styling. The key is to treat it as a structural accessory rather than a decorative one. Three approaches work especially well:

• With a deep side part, secure the larger section of hair behind the ear. The flat top plate sits flush against the head, so it works with both loose hair and a low ponytail.
• With short hair, pin back a fringe or lift a section at the crown. The straight edge of the barrette looks particularly good against a rounded silhouette, so it balances a bob or a soft curl.
• With a silk scarf or a soft knit, echoing the early-1960s look without feeling costumed. Pair the tortoiseshell finish with simple gold or silver-tone earrings.

If you are wearing the navy enamel version for evening, keep the rest of the outfit restrained — a black dress and a single bracelet are enough. The rectangle barrette is a statement piece on its own, and it does not need competition.

The P339 also works well in a low bun. Gather the hair into a loose knot at the nape of the neck, then slide the barrette vertically along the side of the bun to hold it in place. This is a particularly good option for days when you want the barrette to be visible but not dominant. In the 1960s, this was a popular way to wear it with a shift dress and low heels, and the combination still looks current today.

Preservation and Daily Care

The P339 is a sturdy accessory, but it needs thoughtful handling. The most common problem is a weakened spring, which causes the barrette to slip out of the hair. To test the tension, hold the barrette by its top plate and open the jaw with your thumb and forefinger. The jaw should open smoothly and close with a clear snap. If it feels loose or opens too easily, the spring may need replacing — a job for a jeweller who works with vintage pieces.

Cleaning should be gentle. Wipe the top plate with a soft, dry cloth after each wear to remove oils from the hair. If the tortoiseshell overlay has developed a cloudy film, use a slightly damp cotton bud to clean the surface, then dry it immediately. Avoid immersion in water, and never use alcohol-based cleaners, which can dull the cellulose acetate and damage the enamel. For storage, keep the barrette in a soft pouch or a lined box, away from direct sunlight and humidity.

One point that collectors often overlook is the condition of the lower jaw. The jaw is the part that slides under the hair, and it is usually plated with the same finish as the top plate. If the plating has worn away, the bare brass underneath can discolour the hair over time. Check the jaw under bright light before buying, and if you already own a P339 with a worn jaw, have it re-plated by a professional rather than attempting a home repair.

For a more systematic approach to caring for a collection of vintage hair accessories, the C37 Coordinate System offers a collector's method for preserving vintage hair accessories, and it is particularly useful for keeping track of spring tension and finish condition. The same principles that apply to storing vintage C40 hair lanyards — keeping them dry, away from direct light, and in acid-free tissue — apply to barrettes with delicate overlays.

One final practical note: if you find a P339 with a slightly loose jaw but an intact top plate, do not try to bend the metal yourself. The brass base is strong, but the riveted spring assembly is delicate, and a small misalignment can make the barrette unwearable. Instead, take it to a jeweller and ask for a spring replacement. A well-repaired P339 will outlast most modern clips, and the twin-coil mechanism will continue to hold hair securely for another sixty years.