Real-Scale Upholstered Furniture Flammability 

and Effect of Silicone-Based Backcoating

Engineering Laboratory, National Institute of Standards and Technology

Ickchan Kim1, Sung Chan Kim2, Anthony Hamins

1

, Andre L. Thompson 1, Shonali Nazaré

1

, Mauro Zammarano1*

1 Flammability Reduction Group, EL, National Institute of Standards and Technology, Gaithersburg, MD 20899, U.S.A. 

2 Department of Fire Safety, Kyungil University, Gyeongsan-si, Gyeongbuk, 38428, Korea

Introduction

Experimental and Results

In this study, the effectiveness of a NIST developed silicone

backcoating as flame-retardant in upholstered furniture has been

demonstrated by full-scale smoldering and flaming tests. [1] A

silicone-based elastomer filled with vinyl-silane modified aluminumhydroxide is applied to the back of the upholstery fabric to generate

an effective fire barrier with an expected benign toxicological and

environmental profile. The flammability of the chair mock-ups with

pristine uncoated upholstery fabric (UC) and backcoated upholstery

fabric (BC) have been compared by using Cal. TB 133 [2] as flaming

ignition source and NIST SRM 1196 as smoldering ignition source.

Abrasion resistance and flexibility of UC and BC fabrics were also

tested.

References

[1] M. Zammarano et al., Adv Mater Interfaces 3(23) (2016).

[2] California TB 133 Flammability Test Procedure, Department of Consumer Affairs, Bureau of Home Furnishings and Thermal Insulation, North

Highlands, CA, 1991.

Flammability Reduction Group

FLAME 2018, STAMFORD CT, May 2017

Silicone-based Back-Coated Mockup

50 mm

TB 133 

Burner

457 mm

Back cushion

Seat cushion

Heat Flux Gauge 1

Heat Flux 

Gauge 2

Heat Flux Gauge 3

500 mm

Armrest Armrest

t = t1

u (end of burner-on) t = t2

u (burner off) t = t3

u (burner off)

t = t4

u 

(burner off) t = t5

u 

(burner off) t = t6

u 

(burner off)

Uncoated (UC) fabric Chair

t = t1

b (burner on) t = t2

b (burner off) t = t3

b (burner off)

Back-Coated (BC) fabric Chair

0 20 40 60 80 100 120 140 160 180 200

0.00

0.05

0.10

0.15

0.20 Mass Loss (g)

Number of Rotation (x 1000)

 UC

BC

Sample THR [kJ/g] PHRR [W/g]

Polyurethane foam 26.1 ±0.06 555.9 ±5.65

Velvet (100% cotton) fabric 10.3 ±0.08 178.0 ±2.82

Sylgard 65% VSAIOH 3.6 ±0.44 17.0 ±0.92

Chair 

Fabric

Stage I Stage II Stage III Total

PHRRI THRI MLI eff HC,I PHRRII THRII MLII eff HC,II PHRRIII THRIII MLIII eff HC,III THR TML eff HC tot

[kW] [MJ] [Kg] [kJ/g] [kW] [MJ] [Kg] [kJ/g] [kW] [MJ] [Kg] [kJ/g] [MJ] [Kg] [kJ/g]

UC

Fabric 

73.8

±3.5

6.2

±0.3

0.41

±0.00

15.3

±0.7

145

±24.0

24.1

±3.5

1.17

±0.18

20.6

±0.2

178.8

±2.4

28.9

±2.9

1.11 

±0.15

26.1 

±1.0

59.2 

±0.7

2.69 

±0.03

22.6 

±0.1

BC

Fabric

24.2

±0.8

1.3

±0.1

0.15 

±0.00

8.3 

±0.5

1.3 

±0.1

0.15 

±0.00

8.3

±0.5

• Foam: Cal TB 117-2013 polyurethane

• Fabrics: 100% cotton velvet (UC)

• Backcoating (BC) [1] : halogen-free

silicone-based elastomer with 65% by

mass of vinyl modified ATH (VSAIOH)

• Ignition method:

Propane burner by Cal TB 133 with

18kW for 80 s, 1 inch above seat

Classified stages with HRR 

plots of uncoated fabric chair

Stage 1: Gas-burner causes 

combustion of fabrics and TDI of 

polyurethane (for 80 s)

Stage 2: Flame spreads and more 

polyol occurs

Stage 3: Mockup has collapsed 

into a pool of flaming pyrolysis 

products

0 2 4 6 8 10 12 14 16 18

0

20

40

60

80

100

120

140

160

180

200 Stage2 Stage3

UC 2 BC 2 Heat Release Rate (kW)

Time (min)

Stage1

Burner 

 80 (s)

t1

u

t2

u

t3

u

t4

u

t6

u

t5

u

t3

b

t2

t b

1

b

UC mock-ups were fully 

burn by the end of test. 

(Left)

On the contrary, in BC 

mock-ups foam 

combustion was 

negligible ( see below).

The results show that the BC fabric allows to achieve an unusual all-in-one solution for 

flaming and smoldering combustion that improves durability without affecting the aesthetics 

or the comfort of the chair.

BC technology results in extraordinary reduction of flammability. BC chairs have 

PHRR and THR as low as 13.5 % and 2.2 % of UC chairs, respectively. Heat flux 

values up to about 70 kW/m2 are measured.

0

20

40

60

80

100 Heat Flux 1 (kW/m

2

)

UC 1 UC 2 UC 3 BC 1 BC 2 BC 3

Heat Flux on Vertical Cushion

0

20

40

60

80

100 Heat Flux on Seat Cushion UC 1 UC 2 UC 3 BC 1 BC 2 BC 3 Heat Flux 2 

0 2 4 6 8 10 12 14 16 18

0

4

8

12

16

20 Heat Flux in front of Chair UC 1 UC 2 UC 3 BC 1 BC 2 BC 3 Heat Flux 3 

0 2 4 6 8 10 12 14 16 18 Time (min) 0.00

0.02

0.04

0.06

0.08

0.10

0

50

100

150

200 HRR (kW)

UC 1 UC 2 UC 3 BC 1 BC 2 BC 3

0.0

0.1

0.2

0.3

0.4 UC 1 UC 2 UC 3 BC 1 BC 2 BC 3 CO2(Vol. %)

0

20

40

60

80 UC 1 UC 2 UC 3 BC 1 BC 2 BC 3 CO (Vol. ppm) CO/CO2

Time (min)

UC 1 UC 2 UC 3 BC 1 BC 2 BC 3 100 200 300 400 500 600 700 800

0

100

200

300

400

500

600

100 200 300 400 500 600 700 800

0

100

200

300

400

500

600

100 200 300 400 500 600 700 800

0

100

200

300

400

500

600

 Polyurethane

Temperature (degree C)

 Cotton Fabric HRR (W/g) Silica-based 

 elastomer

Micro-Scale Combustion Calorimetry and Abrasion Resistance Tests

Open Flame Test on UC and BC Chair Mock-ups

THR Cal. = ML PUF,Full-Test · Hc PUF,MCC + ML Fabric,Full-Test · Hc Fabric,MCC(Eq. 3)

k · THR Full-Test = THR Cal.(Eq. 1)

eff Hc Full-test= THR Full-Test / ML Full-Test(Eq. 2)

Factor k ≈ 0.999 ± 0.006 for UC fabric chair

Conclusion

28K rotation 90K rotation

28K rotation 90K rotation 180K rotation

UC velvet

BC velvet

Sample Backcoating 

formulation

Area density

[g/m2]

Thickness

[mm]

Flexural 

rigidity [μJ]

UC fabric no backcoating 447.3 ±2.7 1.3 ±0.2 81 ±4

BC fabric vinyl-silane modified

aluminum hydroxide 813.3 ±15.9 1.5 ±0.3 287 ±57

Abrasion resistance test by Martindale abrasion tester