Single Use and Reusable Gowns

Observing, understanding and measuring the properties of single use gowns, and evaluating the likely effectiveness of reusable alternatives.

Report prepared by Tim Pickering

12/05/2020

Aim

• To investigate the properties and performance offered by single use gowns compared to reusable alternatives.

• To identify options for cleaning, and general maintenance of reusable gowns.

Material and Products Used for Testing

• Single Use Light Weight Surgical Gown

• Single Use Heavy Weight Surgical Gown

• Single Use Medline Reinforced Surgical Gown

• Reusable Gown (100% cotton, 150gsm)

• Reusable Gown (35/65% polycotton, 110gsm)

• Reusable Gown (50/50% polycotton, 200gsm)

• Reusable Gown (Guardian Surgical)

• Nikwax PPE Wash.Direct

• Nikwax PPE Proof.Direct

• Bosch Classix 6 Washing Machine

• Tumble Dryer (vented)

Nikwax PPE Wash.Direct and PPE Proof.Direct are only available to professional customers, such as NHS trusts, care homes and services. Instructions and procedures will be issued by

Nikwax on a case-by-case basis, to ensure that product usage levels are correct for the equipment used.

Method Single Use Gowns Gowns were received from two hospital trusts. Samples were taken and assessed for water repellency, using

ISO 4920:2012 (see Appendix), and air permeability. Fibre size of the fabric was qualitatively assessed using microscopy. In the case of the reinforced surgical gown, the reinforced chest panel was also assessed for fibre

size and air permeability.

Reusable Gown Fabrics Cotton and polycotton samples were received from two groups, looking to produce gowns for use in a clinical

setting. An existing reusable surgical gown was also received for testing. Initial spray ratings were taken using

ISO 4920:2012. In this instance, the fabric samples received did not have a durable water-repellent coating

(DWR). A 1m2 of each fabric was taken, and individually washed with Nikwax PPE Wash.Direct on a Cotton

60°C Cycle (to mimic temperature sterilisation) and waterproofed with Nikwax PPE Proof.Direct on a Cotton

60°C. Samples were then tumble-dried for an hour, then conditioned for two hours at room temperature, before

re-assessing spray rating. Air permeability was also measured, once the fabrics had been treated.

The Guardian surgical gown had some level of water repellency, but it was poor. It was elected just to wash it

in Nikwax PPE Wash.Direct to establish the effect on its performance, and measure its air permeability.

Wash Durability – Reusable Gown Fabrics The reusable gown fabrics were taken and washed five times in Nikwax PPE Wash.Direct on a Cotton 60°C

Cycle. Spray rating and air permeability were then measured. Samples were then taken and proofed again

with Nikwax PPE Proof.Direct on a Cotton 60°C cycle, to establish whether a combination of both products

would offer ongoing performance.

Single use gowns were not tested for wash durability in this piece of work.

Results Table 1. Spray Rating of Single Use Gowns

Gown Spray Rating ISO (ASTCC)

Heavy Weight Gown 5 (100)

Light Weight Gown 5 (100)

Reinforced Gown 5 (100) Table 2. Spray Rating of Reusable Gowns

Gown Spray Rating (Initial)

Spray Rating (Treated)

Spray Rating after 5x PPE Wash.Direct

Spray Rating after re-treatment with PPE Proof.Direct

Reusable Gown

(100% cotton,

150gsm)

0 (0) 85 (3.5) 80 (3) 85 (3.5)

Reusable Gown

(35/65%

polycotton,

110gsm)

0 (0) 75 (2.5) 75 (2.5) 75 (2.5)

Reusable Gown

(50/50%

polycotton,

200gsm)

0 (0) 85 (3.5) 85 (3.5) 85 (3.5)

Guardian Surgical

Gown

1 (50) NA 85 (3.5) NA

Table 3. Air Permeability Data for all gowns

Gown Initial (CFM/F2) After Proofing After 5x PPE Wash.Direct

Heavy Weight Gown 10.70 NA NA

Light Weight Gown 70.0 NA NA

Reinforced Gown 40.0 (0.0 on reinforced

chest panel)

NA NA

Reusable Gown

(100% cotton,

150gsm)

15.25 15.25 15.50

Reusable Gown

(35/65% polycotton,

110gsm)

106.50 107.25 106.75

Reusable Gown

(50/50% polycotton,

200gsm)

11.50 11.75 11.50

Guardian Surgical

Gown

32.40 NA 32.50

Fig. 1. Microscopy of reinforced single use gown main fabric, and chest. Left image showing ‘outer’ surface of the reinforced surgical gown, with right image showing reinforced

laminate.

Fig. 2. Microscopy of the 50/50% polycotton 200gsm reusable gown material. Tightly woven polycotton fibres are clearly visible.

Discussion and analysis of results Properties offered by single use gowns Broadly speaking, the main property offered by the single use gowns is water repellency (for repelling bodily fluids), as can be seen from their very good score on the spray rating test. The gowns appear to have been

treated in a PFAS compound, based on the level of beading observed. Water repellency and water absorbency

are critical to surgical gowns, as it prevents a ‘fluid bridge’ forming that pathogens can cross when the fabric

wets out.

Regarding air permeability, there is a variety of protection offered, from very poor, to very good; lower values

indicate that less air can penetrate the fabric. A high air permeability is likely to make a gown more susceptible

to high-velocity particulate matter. The lower the air permeability value can be, the better.

Air permeability can also give an indication of how well a gown will perform in terms of hydrostatic head. If a

gown has a high air permeability, anecdotally it has also been found to have a lower hydrostatic head. It can

be inferred that gowns with lower air permeability will also have significantly lower risk of being penetrated by

droplets of fluid.

Properties offered by reusable gowns

The fabric used in the Guardian Surgical re-usable gown has the potential to be very good. It has a low air permeability, but as received, had low water repellency - which could compromise safety, if enough moisture

was absorbed to form a ‘fluid bridge’. The water repellency significantly improved with Nikwax PPE

Wash.Direct, suggesting that for on-going maintenance, there would be a significant improvement in

performance and safety.

The 50/50% polycotton 200gsm was the next best performing in terms of air permeability, and spray rating,

once treated with PPE Proof.Direct. The air permeability of this gown was only slightly higher than that of the

single use heavy gown. The PPE Proof.Direct significantly enhanced the performance of the untreated fabric.

While not reaching the same outright level of DWR performance as the single use gowns, it did significantly reduce absorbency, which would prevent a ‘fluid bridge’ forming, and therefore maintain safety. The fabric was

also maintainable with PPE Wash.Direct, with the spray rating being maintained after five washes.

A 100% cotton 150gsm fabric also performed well, once treated with PPE Proof.Direct, with low air

permeability, and a good spray rating. Performance was maintained after five washes with PPE Wash.Direct,

with absorbency remaining low. This meant it would be another good candidate fabric for producing reusable

gowns.

The remaining fabric, a 35/65% polycotton at 110gsm, did not perform as well. The air permeability of this

fabric was nearly ten times the value seen with the other cotton and polycotton samples, and was a magnitude

higher than even the lightweight surgical gowns. This would make it susceptible to high-velocity particulate

matter, which may occur in a clinical setting. It was also difficult to get a good result in terms of spray rating.

Although performance was maintained with PPE Wash.Direct, the lower level of water repellency and high air

permeability would suggest this material is unsuitable for gowns.

Assessing air permeability and water repellency can give a good indication as to whether fabric will be suitable

for PPE applications. The maintenance of both properties is crucial in delivering PPE that is reusable.

Sterilisation Gown material must be suitable for sterilisation, either by chemical-based or temperature-based means. In the

case of reusable, water repellent gowns, the most effective means is via temperature sterilisation, as chemical

techniques risk damaging the water repellency of the gowns.

Fabrics were washed at 60°C, as this is the minimum temperature recommended for sterilising materials.

Processes for more safely cleaning reusable gowns In a professional setting, good processes and training are key to maintaining PPE. Staff must be trained to use

60°C+ washes, and dose the correct amount of product reliably. This can be achieved through automatic

dosing, and automation of the washing procedure.

There must also be a quality control program in place, with staff trained to check for levels of water repellency

on all gowns. If the level of water repellency on a gown is reduced, the safety of the gown could be significantly

compromised. This can be simply done by spraying a gown with water, and observing whether water beads

on the surface, or whether darkening occurs under the droplets, as the fabric wets out.

Nikwax products can fit into existing NHS protocols, and therefore are an easy plug-and-play solution for NHS

trusts, or other services looking for methods to look after reusable PPE.

Conclusion Reusable PPE manufactured from good quality, well-specified materials can offer a comparable level of

protection to single use PPE – and in some cases, significantly better protection than single use PPE. High

levels of water repellency, low levels of water absorbency, and low air permeability are key factors in ensuring

that material is fit for purpose. Materials must be durable to high temperature washing, with little to no change

in air permeability and water repellency after more than five washes.

A controlled procedure for cleaning, re-proofing and quality controlling the gowns is also critical to maintaining

ongoing performance, along with ensuring materials are sterile. Use of the correct washing product is critical, with products such as Nikwax PPE Wash.Direct and PPE Proof.Direct specifically designed to maintain these

properties.

Appendix

1) Spray Rating Test - ISO 4920:2012 Textile fabrics: Determination of resistance to surface wetting (spray test)

This provides an indication of the degree of water repellency. The fabric being tested is fastened in position in the ISO spray rating equipment. Deionised water (250 ml) is sprayed at the fabric through a nozzle of defined intensity. The fabric is then compared to standards and rated. The rating range is from 5, where there is “no sticking or wetting to the upper surface” to a rating of 0, where there is “complete wetting of upper & lower surfaces”.