BUT —THE GLASS WAS
Georgian Wired Glass
stays put in frames
15 feet from blitzed
1, 2 and 3. Advertiser Pilkington
Bros., Ltd. Agents F. C. Pritchard
Wood and Partners Ltd.
4. AdvertiserCapper, Pass and Son Ltd. Agents Alfred Pemberton Ltd.
5. Advertiser Concrete Ltd. Agents W. H. Emmett Co., Ltd. 6. Advertiser
Haywards Ltd. Agents Braithwaite and Miller, Ltd. 7. Advertiser Cement and
Concrete Association. Agents Erwin, Wasey and Co., Ltd. Artist Kenneth Petts.
Time anJ 4g»ui (hat remark made when people h.
Glass t-cnMs on be iKed for ARP wort Glass i»n
we have been brought up to believe since the last wo
new powers and it is now a structural material, tough and
ran rem, bias, cm ARMOURUGHTGlasi Ixw«
i the fragile, flimsy thing
THERE IS OFFICIAL PROOF of tha resisting powers of areas
of glass bricks in light frameworks of reinforced concrete.
This will be found in A.R.P. Memorandum No. 12, issued
by H.M. Stationery Office. You will find it under Goncral
Notes, No. 3, sub-section (o), page 20.
The official support for the powers of resistance of
•Armourlight glass lenses appoars In Structural Oefenco,
A.R.P. Handbook, No. 5, chapter 6, section 6. 2.
THIS photograph was taken from
inside some burned-out premises
which adjoined a building glazed
with Georgian Wired Glass in metal
frames. Although a distance of 10 to
15 feet separated the two buildings the
Wired Glass, although cracked, remained
intact in the window frames.
THE WAR GLASSES
Wired Glass js one of the war glasses
with special powers of resistance. There
are also other glasses and glass units
which can give extra strength and
excellent service in war-time structural
work and here are some facts about
I. ARMOURPLATE GLASS
Armouri'I.atk Glass has special powers of resistance
to shock and impact, and to high temperatures. It is
produced in thicknesses ranging from in. to It in.
Its resistance to severe impact is five to six times that
of ordinary Polished Plate Glass of the same thickness.
When broken, this glass disintegrates into innumerable
fragments neither large nor sharp enough to cause
serious injury. It does not splinter, and possesses 10
the full the transparency, lustre, and llatncss of ordinary
Polished Plate Glass. In connection with oihcial tests
with 500-1,0(10 11». boinhs bursting at distances of So ft.
or more, A.R.P. Handbook N»>. 5 Structural Defence,
states, J-in. toughened glass,* solid or hollow
building lenses or gl iss bricks set in concrete frames are
highly resistant to blast,"
A.R.P. Memo. No. 12—"Aims in Window Pro-
Assuming that glass is likely to be broken, window
protection shotila be devised
(u) to prevent damage from flying pieces of glass
(ft) to exclude weather (wind and rain)
(c) to act as obscuration in certain cases.
Wired Glass will provide (a) and (ft). When used in
conjunction with shutters it will also provide (c)
inasmuch as the glass remains in the frame even though
cracked, thus permitting the shutters still to be used
during black-out hours with natural light still available
in the daytime.
Wire reinforced glass is a fire retardativc and will
prevent the spread of fire. It has been approved by
the British Fire Prevention Committee's standards
Specification B. The London County Council has
approved its use as a fire-resisting material.
A department for Technical Problems
This advertisement is issued by Pilkington Brothers
Ltd. Our Technical Department, at St. Helens,
Lancashire, is always available for consultation on
the use of glass under present conditions, in A.R.P.
work, and in any form of structural work.
The toughened glass referred to is Armourplate."
2. "ARMOURPLATE" LENSES
Toughened Lenses have been specially manufactured
for fixing into concrete, and provide approximately
twenty times greater resistance to impact as a similar
lens in ordinary annealed glass. Official tests have
proved that they are highly resistant to blast pressure.
In addition, they provide full protection against an
incendiary bomb burning on the surface of the lens.
3. INSULIGHT GLASS BRICKS;
These are hollow glass units made in two halves arul
scaled together, and are designed for use in vertical
walls. Glass bricks arc laid in the same way as ordinary
bricks, but being a non-load bearing unit they should
Ik- regarded as a panel within a structure. Recent
iKiiubing has shown that they arc highly resistant to
blast pressure, and, as a result of a test at the Building
Research Station Fire Testing Station they have been -
classified Grade I) under the conditions of the British
Standard definitions No. 47H, as a lire resisting building
4. WIRED GLASS
This is a well-known type of glass, but its efficiency,
especially in war-time, is not perhaps fully appreciated.
There have been certain references in A.R.P. publica
tions on the effectiveness of wire netting placed over
windows as a measure of protection, but in wired glass
tlie wire netting is actually embedded and firmly fused
into the middle of the glass itself. In the former case
it is highly probable the blast will break the glass, the
fragments become dislodged, and the wire netting may
remain in the aperture the aperture itself, however,
will l>e left fully open to the weather.
Wire rciiforced glass, on the other hand, is highly
resistant to blast pressure, iuid although the glass may
be cracked, the wire holds it together as a complete
panel and, except in cases of extreme severity, remains
in the window opening.
A.R.P. Handbook No. 5"Structural Defence,"
Glass reinforced internally with wire netting offers
considerable resistance to blast.
A.R.P. "War-time Lighting Restrictions for
Industrial and Commercial Premises," page 9:
If glass is essential, the substitution of plain glass by
wired glass should be considered, especially when
repairs are being made in the ordinary course.
War-time Building Bulletin No. I"Treatment
of Windows," page 4:
It should Ik- noted that it is considered desirable
to use Wired Glass whenever possible, since this has
la-en found, by experiment, to offer high resistance to
blast from a nearby high-explosive bomb.