NATIONAL BUREAU OF STANDARDS REPORT

9366

FINAL REPORT ON .

DUSTING OF ACOUSTICAL MATERIALS

by

Howard T. Arni

U.S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS
THE NATIONAL BUREAU OF STANDARDS

The National Bureau of Standards is a principal focal point in the Federal Government for assur- ing maximum application of the physical and engineering sciences to the advancement of technology

in industry and commerce. Its responsibilities include development and maintenance of the national

standards of measurement, and the provisions of means for making measurements consistent with

those standards; determination of physical constants and properties of materials; development of methods for testing materials, mechanisms, and structures, and making such tests as may be necessary, particularly for government agencies; cooperation in the establishment of Standard practices

for incorporation in codes and specifications; advisory service to government agencies on scientific and technical problems; invention and development of devices to serve special needs of the Govern- ment; assistance to industry, business, and consumers in the development and acceptance of commercial standards and simplified trade practice recommendations; administration of programs in cooperation with United States business groups and standards organizations for the development

of international standards of practice; and maintenance of a clearinghouse for the collection and

dissemination of scientific, technical, and engineering information. The scope of the Bureau’s

activities is suggested in the following listing of its three Institutes and their organizational units. Institute for Basic Standards. Applied Mathematics. Electricity. Metrology. Mechanics. Heat. Atomic Physics. Physical Chemistry. Laboratory Astrophysics.* Radiation Physics. Radio Standards

Laboratory:* Radio Standards Physics; Radio Standards Engineering. Office of Standard Reference

Data. Institute for Materials Research. Analytical Chemistry. Polymers. Metallurgy. Inorganic Materials. Reactor Radiations. Cryogenics.* Materials Evaluation Laboratory. Office of Standard Refer- ence Materials. Institute for Applied Technology. Building Research. Information Technology. Performance

Test Development. Electronic Instrumentation. Textile and Apparel Technology Center. Technical

Analysis. Office of Weights and Measures. Office of Engineering Standards. Office of Invention and

Innovation. Office of Technical Resources. Clearinghouse for Federal Scientific and Technical

Information.**

•Located at Boulder, Colorado, 80301. ••Located at 5285 Port Royal Road, Springfield, Virginia, 22171.
NATIONAL BUREAU OF STANDARDS REPORT

NBS PROJECT m$ REPORT

42104-12-4212443 June 30, 1966 9366

FINAL, REPORT ON

DUSTING OF ACOUSTICAL, MATERIALS

by

Howard !* Arni

Materials and Composites Section

Building Research Division

Institute for Applied Technology

Sponsored by

Office of the Chief of Engineers

Department of the Air Force

Naval Facilities Engineering Command

Washington, D, C*

NATIONAL BUREAU OF ST

for use within the Government, and review. For this reason, th whole or in part, is not authoi Bureau of Standards, Washingt

the Report has been specifically

IMPORTANT NOTICE

Approved for public release by the

Director of the National Institute of

Standards and Technology (NIST) on October 9, 2015

ss accounting documents intended

subjected to additional evaluation

listing of this Report, either in

5 Office of the Director, National

the Government agency for which

opies for its own use.

II. S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS

DUSTING OF ACOUSTICAL MATERIALS

by

Howard T. Arni

1. INTRODUCTION

This project was done under the Tri-Service Engineering Investigations of Building Construction and Equipment at the National

Bureau of Standards. The purpose of the project was to investigate and evaluate methods of testing the dusting and adhesion,

characteristics of acoustical materials.

2. PHASE I

In the first phase of this investigation, the test frame designed

and built by Tectum Corporation and described in Guide Specification CE-219.01, 15 December 1961, was acquired on loan from the

National Gypsum Company and a duplicate of this frame was built

in the NBS shops.

Samples of some sprayed-on acoustical materials were acquired

and were subjected to tests in this frame. Also, small samples

of the same materials were tested in commercial Ro-Tap machines

which were already available in the NBS miscellaneous testing

laboratory, according to a procedure described in brochures of

the Armstrong Cork Company concerning the product, "Limpet".

Descriptions of the features of these two test procedures follow

and data obtained from this series of tests appear in Tables I and II.

2 . 1 Description of Dusting Frame and Tests

This frame is constructed of angle iron, is supported on four

springs, and holds a test specimen approximately 33 x 39 inches.

It is vibrated in a vertical direction, at the rate of 3,600

vibrations ‘ per minute, by a Syntron Vibrator mounted above the

center of the frame. The directions state that the amplitude

of vibration shall be 0.005 ±0.001 inch and shall be measured

by a dial gage. Considerable difficulty was encountered, first,

in devising a method of measuring the amplitude. A method of

using two dial gages, one above and one below, and taking

readings, both with the frame at rest and vibrating, was

- 2 -

finally devised, but it was never found possible to achieve

uniform amplitude of vibration at different points on the frame

Weights had to be clamped to the frame at various points to

achieve a total weight of test frame, vibrator, and specimen

of 275 ±10 pounds. The character, placement, and manner of

placing these weights affected the vibration. During a test,

a sheet of Kraft paper was suspended under the frame to collect

dusted-off material. The dust collected during a 30-minute

preliminary period of vibration was discarded, and that collected during the remaining 23 hours, 30 minutes, of a total

24-hour vibrating time was collected and weighed.

2 . 2 Description of Ro-Tap Tests

The Ro-Tap is a commercial device in use in soil laboratories

for sieving samples of soils and aggregates. A stack of 8-inch

sieves is inserted in the device and is subjected to a rotaryreciprocal motion in the horizontal direction and also to

vertical shocks caused by a weight being alternately raised

and dropped on to the top of the frame over the stack of sieves

In some preliminary tests, square specimens were clamped on top

of the top sieve. This proved unsatisfactory, however, and in

all the tests reported, the sample was cut to an 8-inch circle

that fitted snugly inside the top sieve. Tests were also run with and without the tapping mechanism engaged. Two different

machines were used but no significant difference was detected

between data obtained from the two machines. Ro-Tap tests were

run for one hour and material dusted off during the first five

minutes was discarded.

2.3 Results of Phase I

Tests on the two materials used in this phase indicated that

there was a wide scatter in individual results from supposedly

identical specimens. Problems with obtaining adequate and

adequately-mounted specimens were encountered and problems

with operation of the large frame, mentioned above, caused

troubles. In some cases, notably the Pyrospray specimens in

Table I, large masses of the material sloughed off. There were uncertainties as to how much "testing" the samples had already

been subjected to when received, and handling the specimens

and inserting them in the machines caused damage in some cases.

-3-

3. PHASE II

As a result of the problems encountered in Phase I, it was decided that a better approach would be to obtain samples of

various prepared boards, panels, and tiles, and subject these

to tests in both devices. The amount of dusting obtained from

these materials, it was felt, might serve to establish a criterion which sprayed-on materials could be required to meet in

the same test. Results of tests on various materials for the

vibrating frame and the Ro-Tap machine are given in Tables III

and IV, respectively.

For the vibrating frame, mounting problems arose. Samples which

were too small to span the machine, such as 1 ft x 1 ft or 2 ft x 2 ft tiles, were mounted by cementing them to a gypsum board

backing.

With these materials, there were still large differences between

supposedly identical specimens.

4 . PROBLEMS

Problems with the approach to evaluation of dusting characteristics fell into three main categories: (1) problems with the

test devices themselves and the mounting of the specimens

therein; (2) problems with obtaining adequate samples; and (3)

problems connected with the question of how well-prepared samples

relate to the performance of the materials being tested in any

particular installation in which they might be used.

4. 1 Problems with Test Devices

1. A number of these, especially with the vibrating frame,

have already been mentioned under Phase I above. The problem of

obtaining uniform vibration of the test frame within the tolerance prescribed by Guide Specification CE-219.01 never was adequately solved and is probably insoluble. A compromise of

measuring the amplitude at a spot near one corner of the frame

was adopted in these tests. Also, it is certain that this is

a problem which would have to be faced anew for each new specimen, since they differ in weight, thickness, and stiffness.

-3-

3. PHASE II

As a result of the problems encountered in Phase I, it was decided that a better approach would be to obtain samples of

various prepared boards, panels, and tiles, and subject these

to tests in both devices. The amount of dusting obtained from

these materials, it was felt, might serve to establish a criterion which sprayed-on materials could be required to meet in

the same test. Results of tests on various materials for the

vibrating frame and the Ro-Tap machine are given in Tables III

and IV, respectively.

For the vibrating frame, mounting problems arose. Samples which

were too small to span the machine, such as 1 ft x 1 ft or 2 ft x 2 ft tiles, were mounted by cementing them to a gypsum board

backing.

With these materials, there were still large differences between

supposedly identical specimens.

4 . PROBLEMS

Problems with the approach to evaluation of dusting characteristics fell into three main categories: (1) problems with the

test devices themselves and the mounting of the specimens

therein; (2) problems with obtaining adequate samples; and (3)

problems connected with the question of how well-prepared samples

relate to the performance of the materials being tested in any

particular installation in which they might be used.

4 . 1 Problems with Test Devices

1. A number of these, especially with the vibrating frame,

have already been mentioned under Phase I above. The problem of

obtaining uniform vibration of the test frame within the tole- rance prescribed by Guide Specification CE-219.01 never was adequately solved and is probably insoluble. A compromise of

measuring the amplitude at a spot near one corner of the frame

was adopted in these tests. Also, it is certain that this is

a problem which would have to be faced anew for each new specimen, since they differ in weight, thickness, and stiffness.

-3-

3. PHASE II

As a result of the problems encountered in Phase I, it was decided that a better approach would be to obtain samples of

various prepared boards, panels, and tiles, and subject these

to tests in both devices. The amount of dusting obtained from,

these materials, it was felt, might serve to establish a criterion which sprayed-on materials could be required to meet in

the same test. Results of tests on various materials for the

vibrating frame and the Ro-Tap machine are given in Tables III

and IV, respectively.

For the vibrating frame, mounting problems arose. Samples which

were too small to span the machine, such as 1 ft x 1 ft or 2 ft x 2 ft tiles, were mounted by cementing them to a gypsum board

backing.

With these materials, there were still large differences between

supposedly identical specimens.

4 . PROBLEMS

Problems with the approach to evaluation of dusting characteristics fell into three main categories: (1) problems with the

test devices themselves and the mounting of the specimens

therein; (2) problems with obtaining adequate samples; and (3)

problems connected with the question of how we 11 -prepared samples

relate to the performance of the materials being tested in any

particular installation in which they might be used.

4, 1 Problems with Test Devices

1. A number of these, especially with the vibrating frame,

have already been mentioned under Phase I above. The problem of

obtaining uniform vibration of the test frame within the tole- rance prescribed by Guide Specification CE-219.01 never was adequately solved and is probably insoluble. A compromise of

measuring the amplitude at a spot near one corner of the frame

was adopted in these tests. Also, it is certain that this is

a problem which would have to be faced anew for each new specimen, since they differ in weight, thickness, and stiffness.

-4-

2. The Ro-Tap machine appears to provide a more reproducible test than the vibrating test frame, but its value is

limited by the small size of the specimen tested. Also, the

specimen had to be sawed on a band saw to an 8-inch circle and

fitted into the sieve, and this operation itself subjected the

specimens to a considerable amount of vibration before they

ever were tested.

4 . 2 Problems with Obtaining Adequate Samples

1. The samples were obtained from various suppliers, prepared by them according to their own techniques, and shipped to

the NBS from various distances and by various means. This subjected them to varying amounts of vibration and handling before

test

.

2. It would be better if it were possible to obtain the

materials and prepare the samples in the testing laboratory.

This presents great difficulties, however, because of the wide

variations in the character of the materials and their method

of application. The sprayed-on materials, in general, have

their own special application devices and need speciallytrained personnel for application. Some of these devices use

a slurry of the material premixed in a tub, and in others the

solid and liquid materials are mixed directly in the applying

gun and sprayed by compressed air. On the job, it is often

necessary to spray a number of trial panels in order to adjust

the gun before starting the job.

4 . 2 Relation of Test Specimens to Job Use

1. Sprayed-on acoustical materials are applied to many

different kinds of surfaces in practice. In a warehouse, for

example, they may be sprayed directly on structural steel, cor- rugated steel, concrete surfaces, and exposed pipes. Use of

samples sprayed on a backing such as a piece of gypsum board

would have little value in predicting performance in such installations .

2. The amount and kinds of shocks and vibrations to which

buildings are subjected in various situations are not known and are difficult to evaluate, and the responses of different

-5-

buildings to the same vibrational environment differ. Thus,

it is difficult, if not impossible, to duplicate in a test

method the kind of shock and vibration to which the material

will be subjected in service.

3. As mentioned above, applicators and applying personnel

differ

.

In general, it appears that satisfactory performance of a test panel in any test that could be devised is no guarantee

that the material would perform satisfactorily in any given

future installation, and failure in such a test would not

indicate that the material could not be applied satisfactorily

and give satisfactory performance on a job.

5. RECOMMENDATIONS

1. In view of all the above problems, it is recommended

that the approach of trying to set up a test method to be used

on small sprayed-on specimens be abandoned.

2. For prepared materials such as those used in Phase II,

a test method for small samples may be adequate, though here

too there are wide differences in installation techniques and

in adequacy of installation.

3. The Ro-Tap appears to be a better device for the

latter purpose because of the problems of non-uniform vibration

and of specimen mounting with the vibrating test frame.

USCOMM-NBS-DC

TABLE I

Tests of Sprayed-on Acoustical Materials

on Large Vibrating Frame

Material Total

- -i. per sq

Cafco Soundshield, "85”, #1 0.2231 0.0298

Cafco Soundshield, "85", #2 0.0955 0.0127

Cafco Powershield, #1 0.1501 0.0200

Cafco Power shield, #2 0.0841 0.0112

Cafco Soundshield, #1 0.2150 0.0287

Cafco Soundshield, #2 0.1321 0,0176

Cafco Heatshield, #1 0.1741 0.0232

Cafco Heatshield, #2 0.0310 0.0414

Cafco Type D, #1 0.1620 0.0216

Cafco Type D, #2 0.1065 0.0142

Cafco Blazeshield, #1 0.0745 0.0099

Cafco Blazeshield, #2 Specimen damaged.

BEH Pyrospray, #1 190.0 25.4

BEH Pyrospray, #2 35.2 4.70

TABLE II

Tests of Sprayed-on Acoustical Materials

on Ro-Tap Machine

Material

Total. Amount of Dust in 55 min. » s • With Tap Without Tap

Machine #1 Machine #2 Machine #1 Machine ;

0.0821 0.0445 0.0339 0.0039

Cafco Soundshield 0.0739 0.0265 0.0052 0.0249

0.0545 0.0306 0.0290 0.0675

0,0213 0.0077

BEH Pyrospray

0.0217 0.0070

TABLE III

Tests of Tiles and Panels on Large Vibrating Frame

Material

Gold Bond Fire-Shield

solitude panel with

gypsum topping

Same without gypsum

topping

Water fetted mineral

wool without gypsum

topping

Travertine ceiling

panels without

gypsum topping

Pin-perforated

panels, 2'x4',

painted both sides

with vinyl

Acoustone, foilbacked, l'xl' tiles,

starch bound mineral

wool (glued to gypsum

board backing)

Styletone, fissured

mineral tile, l'xl'

Acousti-Shell flat

panel, fiber glass

acoustical tile

Fissured tile, 2'x2'

Spintone acoustical

panels, 2'x2'x5/8",

1161 pierced pattern

Tectum, 4*x4'x2",

backed with building

paper

Amount of

Manufacturer Total

National 0.0127

Gypsum Co. 0.2177

same 0.0812

1.7656

0.3012

UoS. Gypsum 0.0497

Co. 0.0300

Gustin-Bacon 0.0040

Manufacturing 0.0442

Co

.

Owens-Corning 0.0157

Fiberglas 0.0184

U.S. Gypsum 0.1107

Co. 0.0209

Baldwin- 0.1147

Ehret Hill, 0.0082

Inc.

Johns- 0.0172

Manville 0.0067

National 0.0537

Gypsum Co. 0.1067

Johns- 0.0394

Manville 0.0730

National 0.1498

Gypsum Co. 1.4719

Dust in 23 1/2 hrs, g.

per sq ft

0.0016

0.0290

0.0107

0.2356

0.0401

0.0066

0.0040

0.0005

0.0059

0.0021

0.0025

0.0147

0.0028

0.0153

0.0011

0.0023

0.0009

0.0072

0.0142

0.0053

0.0097

0.0200

0.1967

TABLE IV

Tests of Tiles and Panels on Ro-Tap Machine

Total Amount of Dust in 55 min. , g

Material Manufacturer With Tap Without Tap

Gold Bond solitude

acoustical tile,

needlepoint design

National

Gypsum Co.

0.0130

0.0340

0.0100

0.0055

Acoustone incombustible

tile, foil-backed,

starch bound, mineral

wool, fissured pattern

U.S. Gypsum

Co

.

0.0170

0.0201

0.0330

0.0601

Styletone non- combustible

mineral tile, fissured

Baldwin-Ehret

Hill, Inc.

0.0095 0.0070

Travertine ceiling panel Gustin-Bacon

Manufacturing

Co .

0.0045 0.0005

Gold Bond Fire-Shield

solitude panels

National

Gypsum Co.

0.0316 0.0130

Water (wet) fetted

mineral wool ceiling

panels, fissured and

needlepoint

U.S. Gypsum

Co.

0.0205 0.0050

Acousti-Shell flat

panels, 2'x2'

Johns -Manville 0.0021 0.0000

Tile, 2 'x2National

Gypsum Co.

0.0080 0.0017

Spintone acoustical

panels, 2'x2'

Johns -Manville 0.0053 0.0020

Film-faced textured

tile

Owens -Corning

Fiberglas

0.0033

0

0.0025

Frescor tile, 5/8" Owens -Coming

Fiberglas

0.0228 0.0123

Tectum, 2" backed with

building paper

National

Gypsum Co.

0.0545 0.0080

Tectum, 1" without

backing

National

Gypsum Co.

0.0704 0.0237

Pin-perforated panels,

2'x4', painted both

sides

Owens -Corning

Fiberglas

0.0172 0.0037

Sanofaced, 2'x4' Owens -Corning

Fiberglas

0.0178 0.0030