- 1 Introduction
- 2 Specifying The Flame-Resistant Fabric
- 3 Difference Between Inherent And Treated Flame-Resistant Fabrics
- 4 Manufacturing Process of Flame-Resistant Workwear Fabric
- 5 Endnote
The importance of flame-resistant fabrics in today’s industrial world is well established. However, it is only after in-depth knowledge into the making of Flame-Resistant fabrics that companies can make the best suitable choice for the workwear fabric for their employees.
Every high-risk industry has its own specifications for the employees’ uniform clothes which may include common properties from strength, consistency, reliability, breathability, and sturdiness to more technical requirements such as heat resistance, arc flash resistance, acid proof fabrics, fire resistance fabric, molten metal resistance, etc.
It is essential that the workwear fabric lives up to the challenges of the work environment. Since these qualities are incorporated into the fabric during the manufacturing process, it is important to understand what types of input different manufacturing stages entail for the performance of the finished FR fabric.
Specifying The Flame-Resistant Fabric
As much as it is important to do your math and calculations for specifying the fabric for your Flame-Resistant workwear requirements, nothing beats the effectiveness of practical wear trials. Wear trials are the best way to acquire comprehensive evaluation of important factors in choosing the right fabric for your work conditions and determine the performance, comfort level and practicality of the fabric in a given hazardous environment.
Wear trials are also the way to obtain first-hand feedback from the employees on how the garment fabric scales on the workspace requirements and everyday challenges. Following guidelines may help in producing reliable feedback from the wear trials.
- Select a workwear fabric based on your prior research limiting the number of fabrics choices.
- It would also be best to involve few employees from different units and shift timings to warrant consistent feedback across the entire organization.
- Prepare the feedback survey using standard questions and easily understandable ranking scales (e.g. a 5-point scale) so that measurable feedback can be recorded.
- In order for deeper understanding, allow for separate evaluation for fabric and garment selection to understand where the problem lies, if any – with the fabric or the garment design.
- It is also recommended to ask for comments or open-ended questions in order to add context to the data.
Difference Between Inherent And Treated Flame-Resistant Fabrics
The FR fabric is either made from inherently flame-resistant fibers or else a non-FR fabric is treated chemically to give it flame-resistance qualities. Inherent FR fabrics are prepared using fibers that naturally have FR properties integrated into the filament which cannot be removed at a later stage. It means that the resultant fabric has FR qualities for life.
Treated FR fabrics become flame resistant by applying the fabric with a flame-retardant chemical finish either at the fiber stage or woven fabric stage. This chemical treatment modifies the molecular structure of the filament giving it FR properties for the life of the fabric is used and washed according to given instructions.
Treated fabrics usually weigh more than the inherent FR fabrics which add to their performance in many workspace conditions by putting more mass between the wearer and the hazard. However, this may result in a compromise for the comfort of the fabric or even add to heat strains.
Manufacturing Process of Flame-Resistant Workwear Fabric
Fiber Selection and Blending
The fabric production starts with the selection of the raw materials such as cotton or other blends to be added such as polyester. The important properties to look for in the fiber are fiber length, strength, color grade, trash and leaf grade. Bales of cotton are selected and blended together in order attain optimized yarn quality and strength.
The opened fiber than goes into carding. This process involves removal of any foreign matter and short fibers from the cotton to ensure superior yarn quality and consistency which results in the durability of the fiber and consequently the ending finished fabric. Next, the cotton is consolidated into a loose strand which is a rope-like form, card sliver.
Spinning and Slashing
This is where the slivers are drawn and twisted together to form yarns and wound into packages. These packages are further loaded onto a creel and the yarn is wound around a section wheel for slashing. This is the beam that is later placed onto a loom to produce the fabric.
In the slashing process, the warp yarns are coated with a mixture – traditionally starch and a lubricant – called sizing which protects and lubricates the yarn during the weaving stage. This improves the weaving performance and in turn the fabric quality.
If the fiber is an inherently FR fiber, it will make an inherently FR Yarn. So the yarn now would be flame resistant itself.
After fiber selection, this is the next stage where the further strength, quality, and comfort of the fabric are ensured. Here, the prepared yarn is woven into the fabric. As the flame-resistant fabrics require extra strength and consistency of quality, they can be made more consistent by weaving them on the same looms with same properties such as construction, yarn tension, weft insertion rate, reed width, and off-loom width.
The consistency in these factors ensures high-quality construction and optimal performance of the resultant fabrics. The common weave patterns used for flame-resistant fabrics are as follows:
- Basic Weaves: Plain, Twill, Satin
- Compound Weaves: Double weave, Jacquard weave
At this stage, the woven fabric goes through multiple steps including singeing, desizing, scouring, bleaching, and mercerization. Singeing is done to burn off loose or long fibers to attain a smooth surface, and reduce fabric piling during a wash and wear cycles.
Next, the fabric is desired to remove the cornstarch and lubricating agent formerly applied during the weaving process. This step is essential in order for the fabric to respond optimally and consistently to dyes and FR treatment.
Then the fabric is bleached using hydrogen peroxide to get increased fabric whiteness. From here, the fabric is ready for mercerization which involves treating the fabric with sodium hydroxide to improve permeability, sheen, reactivity, and dyeing properties of the cotton fabric. Now the fabric is ready for dyeing. As a priority, dyes from the class known as vats are preferred for flame-resistant cotton fabrics and blends for their best wash and lightfastness properties.
Again, the inherently FR fabrics are basically ready at this stage for quality assurance. However, other fabrics go into flame-retardant chemical treatment from here.
For fabrics made from cotton and cotton blends, the fabric is applied with flame-retardant chemicals at this stage to turn it into an FR fabric. This is a closely regulated and complex process where an invisible layer of FR protection is applied to the fabric.
This finish is achieved either by way of a phosphonium salt pre-condensate polymerized with gaseous ammonia (THPOH-NH3), or a heat-cured dialkylphosphonamide. These processes give the fabric its flame retardant qualities, ready to be tested for quality assurance.
After the chemical treatment has been done, the fabric is ready for inspection to ensure the fabric meets the ASTM and NFPA standards for flame resistance. From here, the fabric goes to the garment manufacturing unit.
Having specified the fabric for your FR workwear, it is also important to select a reliable fabric supplier to ensure quality and consistent product supply. Unquestionably, the best choice for your investment would be a supplier with vertically integrated manufacturing units since they will be able to provide the most reliable fabric or garment for you.
The reason being that a garment manufacturer may buy base materials, or greige fabric, from another supplier or in most cases, multiple suppliers. With so many suppliers, it is hard to ensure consistent quality of the fabric and dependable responsiveness to FR treatment due to differences in factors such as fiber quality, width, weight, shrinkage, strength, shade, and color retention.