formula 150, MIL-P-24441, 2- to 4-mils dry-film
MIL-P-24441, 2- to 4-mils dry-film thickness,
thickness, or an equivalent coating.
according to NSTM, chapter 631.
Surface Wetting Coat
One part rubber latex mixed thoroughly with 2
The on-deck magnesia insulation should be
parts underlay powder by weight should be brushed
trowelled smooth, a minimum of 1 inch thick over
on in a thin coat, assuring that all of the deck is wetted
rough finish latex underlay MIL-D-3135, type I.
thoroughly. The purpose of the wetting coat is to
Apply a one-eighth inch minimum thickness of
assure that the underlay bonds securely to the surface.
underlay. Exposed aluminum fittings should be
protected from corrosive attack from the magnesia by
Underlay Body Coat
either a coating satisfactory for aluminum (see NSTM,
chapter 631) or a suitable covering such as a wrapping
Mix thoroughly 1 part rubber latex, 1 1/2 parts of
of a vinyl tape.
underlay powder, and 1 1/2 parts aggregate (all by
weight). Mix only in such quantity that the material
will not set up before application. Make certain there
are no dry particles left. The following approximate
Rubber terrazzo, which is used in washrooms,
quantities of materials are required to cover 100
showers, sculleries, and water closets, is a colored
square feet (one-fourth of an inch thick):
material that contains chips of white and colored
49 lb rubber latex
marble. The material is mixed at the time of
application and is applied with trowels; it requires
73 lb underlay powder
machine grinding to provide a smooth surface. The
73 lb underlay aggregate
usual thickness of application is one-fourth of an inch.
The material may be applied to a maximum of one-half
While the surface wetting coat is still wet, trowel
of an inch without causing the wet mix to sag. If
on the underlay body coat and level off with battens.
greater thickness must be used, apply latex underlay
After leveling off, go over the surface with steel
trowels, working down hard to flow the mix together
and to blend it with the surface wetting coat. Allow
The materials required for mixing rubber terrazzo
the surface to dry hard (at least 2 days) before applying
are as follows:
the deck covering. If the underlay is used in excess of
one-half inch thick in one layer, it will tend to develop
hairline cracks. Latex underlayment for use under
deck tile and resilient sheeting should conform to
MIL-D-3135, type II, and should be installed
Terrazzo mix (including aggregate)
according to the manufacturer's directions. Type II
can be featheredged and trowelled to a smooth finish
Before rubber terrazzo is applied, the deck surface
and 4 inches of vertical bounding surfaces against
which the covering will abut must be cleansed by
wirebrushing or similar methods. If necessary, the
Insulation underlay may be used to prevent
deck should be faired with underlay in low spots and
around rivets and welds.
heat from the overheads of machinery spaces,
After the deck has been cleaned, give it a wetting
especially where these surfaces form the decks of
coat of grout. Mix, apply, seal, and grind the terrazzo
living spaces. The magnesia insulation that is used
according to the manufacturer's instructions. Allow
should conform to MIL-D-23134.
the terrazzo to dry for 72 hours before grinding it.
After grinding, clean the deck with a broom or a
vacuum cleaner. This should produce a smooth,
durable, nonporous surface in which the marble chips
Remove and clean the deck free of rust, dirt, old
are uniformly distributed and firmly embedded. Cover
paint, oil, and grease. Apply one coat of epoxy primer,