USG IMPERIAL Basecoat Plaster User Manual

Page 4

MPERIAL

Brand

Machine application of I

MPERIAL

Brand Basecoat Plaster (MA) requires special equipment that provides for auto

Basecoat Plaster

matic catalyst injection. The machine should be operated in strict accordance with the manufacturer’s directions.

(machine-applied)

Successful results require advance job planning and operator training. The plaster base should be protected
from overspray or contamination by lime or casein materials. Such materials adversely affect the bonding
characteristics of plaster. Mask all areas to be protected from plaster overspray with plastic sheeting or paper
secured with masking tape.

Mix one to three 3-lb. bags of USG

™

Accelerator—Alum Catalyst in 3 gal. of clean water in a plastic pail. The

amount of catalyst used will be determined by the desired setting time. Stir until the material dissolves, then let
the residue settle and pour the solution into the accelerator tank of the machine.

Mix the plaster as previously described and pour it into the machine through the 8x8-mesh screen hopper.
Adjust water in plaster mix until 75% to 90% will pass the screen without shaking.

Caution:

Clean the mixing

equipment after each batch. Clean the hopper and screen free of set plaster to avoid acceleration. The machine
should be completely cleaned after each four hours of use. Adjust the setting time by controlling the catalyst
flow at the machine. Test by spraying plaster on plaster base scrap.

With the setting time adjusted to 30 minutes, spray the taped joints and corner-bead flanges in a pattern wide
enough to cover the tape and metal trim flanges. Immediately trowel level, completely embedding the tape and
metal-component flanges. Leave no voids. Allow to set before plastering. This initial spraying is not required over
S

HEETROCK

Brand Setting-Type Joint Compound (D

URABOND

or E

ASY

AND

Adjust the set for 20 to 30 minutes, then spray I

MPERIAL

Brand Basecoat Plaster (MA) over the entire area to a

thickness of 1/32

Љ, then immediately cross-spray to a total thickness of 1/16Љ. Allow the plaster to set and dry

sufficiently to provide proper suction for the finish coat.

Apply the finish as described above for hand-applied basecoat.

MPERIAL

Brand

The surface must be porous and develop proper suction or be scored to provide adequate mechanical bond.

Basecoat Plaster

Lightly spray the walls with water to provide uniform suction. Fill and level all voids, depressions and joints with

applied to

MPERIAL

Brand Basecoat Plaster and allow it to set; then apply subsequent coats as with gypsum base applica-

concrete block

tion, leaving the final surface rough and open to provide proper bonding of the finish coat.

MPERIAL

Brand

Prepare the surface with an application of USG

™

Plaster Bonder. Fill all voids and depressions with I

MPERIAL

Basecoat Plaster

Brand Basecoat Plaster and allow it to set and partially dry. Then apply I

MPERIAL

Brand Basecoat Plaster as with

applied to

gypsum base or concrete block.

Important:

As no suction is provided over surfaces treated with a plaster bonding

monolithic concrete

agent, it is essential that the applied basecoat surface be raked or broomed once the material has become firm
for a rough and open surface to provide proper suction for the finish coat. Failure to do so may result in delami-
nation of the finish material.

SAFETY FIRST!
Follow good safety practices.
Read material safety data
sheets and related literature on
products before specification
and/or installation.

Trademarks
The following trademarks used
herein are owned by United
States Gypsum or a related
company: C

HAMPION

, D

IAMOND

URABOND

, E

ASY

AND

, I

MPERIAL

, S

HEETROCK

, S

TAR

TRUCTO

-G

AUGE

and USG.

Note
Products described here may
not be available in all geo-
graphic markets. Consult your
U.S. Gypsum Company sales
office or representative for
information.
Notice
We shall not be liable for inci-
dental or consequential dam-
ages, directly or indirectly sus-
tained, 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 lia-
bility 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.

Manufactured by
United States Gypsum Company
125 South Franklin Street
Chicago, IL 60606

800 USG.4YOU (874-4968)
www.usg.com

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