18 gauge back tension spring 40cm

18 Gauge Upholstery Back Tension Springs, Parker Knoll Style

Flexible Replacement Springs for Sofa and Armchair Backs

The 18 Gauge Upholstery Back Tension Springs are designed to provide comfortable, flexible support in traditional and modern upholstered furniture It has hooked extension-spring systems.

Commonly associated with Parker Knoll chairs and sofas, these lighter-gauge springs are particularly suitable for furniture backs, where a softer and more responsive spring action is required.

Unlike heavier seat springs, which must support more direct body weight, 18-gauge back springs offer a more flexible response, helping the upholstered backrest move comfortably under pressure.

Available in six lengths from 36cm to 46cm, they are used for replacing damaged, stretched or broken springs in compatible furniture.

Features

• 18-gauge construction, provides lighter, more flexible spring action.
• Softer back support, made for upholstered furniture backs rather than heavily loaded seats.
• Parker Knoll-style applications, suitable for compatible traditional sprung furniture.
• Hooked ends, designed to attach to appropriate furniture spring fixing points.
• Six available lengths, 36cm, 38cm, 40cm, 42cm, 44cm and 46cm.
• Use it for restoration, useful when replacing broken or weakened backrest springs.
• Professional upholstery use, suitable for furniture repairs, restoration workshops and new manufacture using compatible spring systems.

Why Use 18 Gauge Springs for Furniture Backs?

Seat and back springs perform different functions within an upholstered chair or sofa.

A furniture seat must support a proportion of the occupant's weight and therefore generally requires a stronger, firmer spring arrangement.

A backrest, however, needs to provide controlled flexibility, allowing the occupant to lean comfortably backwards without excessive resistance.

18-gauge back tension springs are lighter and softer than 14-gauge seat tension springs, making them more suitable for compatible backrest applications.

Using the correct spring gauge helps preserve the original feel and movement of the furniture.

Replacing a lighter back spring with a much stronger seat spring may make the backrest unnecessarily firm and could place additional stress on the original fixing arrangement.

For firmer seat applications, see the 14 Gauge Plastic Covered Tension Springs.

Replacement Springs for Parker Knoll Furniture

Parker Knoll furniture is well known for its sprung seating and backrest construction, with certain traditional designs using hooked tension springs secured to metal fixing plates.

When restoring an older Parker Knoll chair, the condition of these springs can affect the comfort and support of the backrest.

Over time, springs may become stretched, corroded or damaged, or their hooks may fail.

Replacing a damaged spring with one of the correct gauge and length can help restore the original support characteristics.

However, Parker Knoll manufactured numerous furniture designs, and spring specifications can vary.

Always compare the original spring, hook arrangement and fixing points before ordering. A particular spring should not be assumed compatible simply because the furniture carries the Parker Knoll name.

Available Spring Lengths

Spring section length	Approximate length in inches
36cm	14.2"
38cm	15.0"
40cm	15.7"
42cm	16.5"
44cm	17.3"
46cm	18.1"

Important: The listed dimensions refer to the coiled spring section only.

Each end has an additional hook measuring approximately 1/2 inch (12.7mm).

Consequently, the complete relaxed spring, including both hooks, is approximately 25mm longer than the nominal spring-section measurement.

How Much Tension Should Be Applied?

These upholstery back tension springs should normally be extended by approximately 1/2 inch to 1 inch (12.7, 25.4mm) when fitted.

Correct tension is essential to the performance of the spring.

If insufficient tension is applied, the backrest may feel loose and fail to provide the intended support.

Excessive tension can make the backrest unnecessarily firm and place additional strain on the springs, fixing plates and furniture frame.

Always check the original installation arrangement and the condition of the fixing points before fitting replacements.

Don't Forget the Spring Fixing Plates

Many traditional upholstery tension-spring systems use metal fixing plates secured to the furniture frame.

These plates provide attachment points for the spring hooks and help maintain their positioning.

When replacing springs, it's worth checking the fixing plates for:

• Worn or enlarged spring attachment holes.
• Corrosion or distorted metalwork.
• Loose or damaged frame fixings.
• Signs of previous repairs or alterations.

Replacing a damaged spring without addressing a worn fixing plate may result in further problems.

see Upholstery Tension Springs and Fixing Plates for related components.

Installing Replacement Back Tension Springs

Before installing replacement springs, carefully inspect the existing furniture construction and identify the original spring arrangement.

For best results:

1. Measure the relaxed coiled section of an undamaged original spring, excluding the hooks.
2. Confirm that an 18-gauge back spring is required.
3. Inspect the furniture frame and metal fixing plates.
4. Attach one spring hook to its appropriate fixing point.
5. Carefully extend the spring to engage the opposite hook.
6. Check the installed tension and ensure the spring is correctly aligned.

Safety note: Tension springs store energy when extended. Wear suitable eye protection, keep the frame secure and use appropriate tools when fitting or removing springs.

Upholstery Back Springs Versus Seat Springs

18 Gauge Back Tension Springs

made for softer, more flexible backrest support in suitable sofas, armchairs and traditional sprung furniture.

14 Gauge Plastic Covered Seat Tension Springs

Manufactured using heavier-gauge wire to provide firmer support in compatible seat suspension systems. The protective plastic sleeve helps reduce direct rubbing between the spring wire and surrounding upholstery materials.

The two types should not be treated as interchangeable.

18 Gauge Upholstery Back Tension Springs provide softer, flexible support for sofa and armchair backs, including many traditional Parker Knoll furniture designs.

• 18-gauge spring wire, lighter and more flexible than seat tension springs.
• Use it for Parker Knoll-style chair repairs, sofa backs and furniture restoration.
• Six lengths available: 36, 38, 40, 42, 44 and 46cm.
• Sold individually, select the quantity required.
• Correct measurement: Lengths exclude the 1/2" hook at each end.
• Fitting tension: Extend by approximately 1/2", 1" when installed.

Don't forget your fixings! Check the 17" Tension Spring Fixing Plate for replacing worn or damaged spring mounting plates.

Replacing seat springs too? see the 14 Gauge Plastic Covered Seat Tension Springs.