USG STRUCTO-BASE Gypsum Plaster User Manual
Preparation In cold weather,all glazing should be completed and the building heated to a minimum of 55 °F (13 °C) before
gypsum base or lath and plaster installation. The temperature of the building must be maintained in uniform range
above 55 °F for an adequate period prior to application of plaster,while plastering is being done, and until plaster
is dry.Heat should be well distributed in all areas, with deflection or protective screens used to prevent concentrated
or irregular heat on the plaster surfaces.
Ventilation and air circulation should be provided to properly dry the plaster subsequent to plaster applications
and proper set. This can be accomplished by keeping windows open sufficiently to provide air circulation in
glazed buildings; in enclosed areas lacking normal ventilation, provisions must be made to mechanically remove
moisture-laden air.
If glazed sashes are not in place and the building is subject to hot, dry winds or temperature differentials from
day to night of 20 °F (11 °C) or more, openings must be screened with cheesecloth or similar material.
Application Mixing STRUCTO-BASE Brand Gypsum Plaster is to be mixed with sand aggregate for machine application or hand applica-
Conventional
tion. When mixing S
TRUCTO-BASE Brand Gypsum Plaster for application in STRUCTOCORE Security Wall Systems, the
Plaster
initial plaster mix is applied as a fog coat 1/8 to 1/4 thick prior to the scratch coat. See Technical Folder SA1119
for information on specific mixes for using S
TRUCTO-BASE Gypsum Plaster in STRUCTOCORE Security Wall Systems.
Applying Mix basecoat plaster by hand or in a mechanical mixer to a uniform consistency.Apply the basecoat plaster by
Basecoat
hand or machine in one or two coats. Monolithic or unit masonry surfaces that exhibit high suction should be
moderately wetted immediately before plastering.
For two-coat work over gypsum lath and masonry, apply the S
TRUCTO-BASE Brand Gypsum Plaster basecoat with
sufficient material and pressure to form a good bond to the base and to cover well; then double back to bring
the plaster out to grounds. Straighten to a true surface with a rod and darby without the use of additional water
and leave it rough to receive the finish coat.
For three-coat work over metal lath or other substrates when desired, apply the S
TRUCTO-BASE Brand Gypsum
Plaster scratch (first) coat with sufficient material and pressure to form good full keys on metal lath, and good
bond on other bases, and then cross-rake. Apply brown (second) coat after scratch (first) coat has set firm and
hard. Bring out to grounds and straighten to a true surface with a rod and darby without the use of additional
water. Leave the brown coat rough to receive the finish (third) coat.
When applying S
TRUCTO-BASE Brand Gypsum Plaster over STRUCTOCORE Steel Sheets in the STRUCTOCORE Security
Wall Systems, a fog coat 1/8 to 1/4 thick is applied as the initial coat, prior to the application of scratch coat
and brown coat. See USG publication SA1119 for information on applying S
TRUCTO-BASE Brand Gypsum Plaster
in S
TRUCTOCORE Security Wall Systems.
STRUCTO
-BASE
®
Brand
Gypsum Plaster
Application Tips
Manufactured by
United States Gypsum Company
125 South Franklin Street
Chicago, IL 60606
800 USG.4YOU (874-4968)
www.usg.com
P847/2-04
©2004, United States Gypsum Company
Printed in U.S.A.
Trademarks
The following is a trademark of
USG Corporation: S
TRUCTO-BASE,
S
TRUCTOCORE, USG.
Note
Products described here
may not be available in all geographic markets. Consult your
U.S. Gypsum Company sales
office or representative for
information.
Notice
We shall not be liable for incidental or consequential damages, directly or indirectly sustained, nor for any loss caused
by application of these goods
not in accordance with current
printed instructions or for other
than their intended use. Our liability is expressly limited to
replacement of defective goods.
Any claim shall be deemed
waived unless made in writing
to us within thirty (30) days from
the date it was or reasonably
should have been discovered.
SAFETY FIRST!
Follow good safety practices.
Read material safety data
sheets and related literature on
products before specification
and/or installation.
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