Old House Journal – September 2019

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Q:

This device is located in the stairwell of our

house, which was built in 1780 and had a

major rehabilitation in 1920. The metal bell is

perforated. On the shield-shaped thing attached

to it is etched what appears to be “Shur-Stop.”

Any idea what it is? —Bob Kennedy, Wilmington, Delaware

A:

At first we thought it looked
like an old vent pipe, or part
of a gutter system, but neither would
be installed near a staircase. When you
mentioned finding an old “grenade fire
extinguisher” in your garage, we had our
clue: Shur-Stop was one of many compa-
nies selling fire-suppression devices from
about 1870 through the 1940s. They’re
often found in boiler rooms, garages,
and kitchens; as a staircase may create
a chimney effect during a fire, someone
added an extinguisher here. The metal

bracket remains, but you’re missing the

liquid-filled bulb.

Some of these glass balls or bulbs

were meant to be thrown, grenade-like,

at the base of a fire. Yours was meant to

shatter or be triggered from the heat of

a fire, releasing the contents, which the

perforations dispersed over the fire. After

about 1900, the liquid inside was carbon

tetrachloride, which sucks oxygen out

of the air, thus removing fuel for the fire.

It was certainly more effective than the

pint of saltwater in earlier versions! But

today we know that carbon tet is a nasty

chemical that causes damage to multiple

organs, is a probable carcinogen, and—

when exposed to high heat—may produce

phosgene gas, an early chemical weapon.

A lively collectors’ market exists, es-

pecially for the Victorian-era “grenades”

that featured colored or patterned glass

and fanciful (often brass) brackets. It is

possible to drain the chemical and replace

it with water, but the work must be done

professionally under stringent conditions,

and thus is expensive. —Patricia Poore

LEFT This perforated “cone” hangs in the stairwell. BELOW (left to right) A similar holder

with its glass grenade; this hammered-brass version has a trigger arm that breaks the

glass under high heat; this is the bulb only, filled (we hope) with saltwater.

Have a Question?

We’re guessing you’ve had some issues
with wood not taking stain evenly, or
you’ve gotten an inconsistent sheen after
clear-finishing. Sanding sealer is a softer,
faster-drying product used over raw (and,

with some products, stained) wood, to

be followed by your finish coats. Shellac

is often used as a sanding sealer. Wood

conditioner is a pre-stain treatment that

reduces the blotchiness that comes from

the wood taking stain unevenly. Grain

filler fills the pores in open-grained wood

species, so the finish will be even with

little to no wood texture. Your stain, sealer,

and finish must be compatible; stick to one

manufacturer and get advice at the paint

store. If you can’t purchase a sealer for oil-

based poly or varnish, thin the first coat by

10–15% with an appropriate thinner. Most

manufacturers do not recommend thin-

ning waterborne finishes. —the editors

Restoring this house means I’ve been doing a lot of wood finishing—some of it

on previously finished or newly stripped old wood, and some on replacement

work, including furniture and recently a new chair rail. Should I be using a

sealer before the final finish? —Tim Butler, Aurora, Illinois