Specification

ManualsBrandsUSG ManualsPaint1.5 lb. Standard-Strength Retarder

Description

USG retarders are additives that lengthen the setting time of gypsum plaster by slowing the chemical crystal

formation that causes the gypsum plaster to set or harden.

USG offers two retarder products to meet a wide range of needs. USG standard-strength retarder is

recommended for slight to moderate (30 to 45 minutes) lengthening of set times of veneer and conventional

plasters as well as setting-type joint compounds. USG retarder for lime-containing plaster products is used with

DiamonD veneer ﬁnish, ReD Top

ﬁnish plaster and ReD Top

gauging/lime ﬁnishes.

Limitations – Excessive additions of retarder will drastically reduce strength, thereby impairing the integrity of the ﬁnish work.

– Excessive amounts may produce “dry-out”—the inability of plaster to set before the water necessary for chemical

reaction evaporates.

– USG retarders should never be added directly to the plaster mix. While this practice may perform adequately,

it is not recommended. The addition of dry retarder does not provide controlled dispersion as quickly or uniformly

as retarder pre-mixed with water.

Directions Application—General Prior to use of any additive, mix a trial batch of formulated product and determine the set time. Once the set

time is known, a measured amount of USG retarder/water mixture is added to adjust the set. Any available

container (wax cup, coffee can, measuring cup, etc.) can be used to measure the retarder/water mixture.

Keep mixing equipment clean between batches to prevent altered setting in subsequent mixes.

Application—USG Standard All retarders should be mixed with water before adding to plaster. Mix one teaspoon of dry USG standard-

Strength Retarder

strength retarder with ﬁve ﬂuid ounces of water to prepare a solution that will extend the set time of 100 pounds

of gypsum plaster by 30-40 minutes or more.

For larger quantities, mix an entire 1-1/4 lb. container of USG standard-strength retarder with ﬁve gallons of

water in a convenient size container to prepare the retarder solution. Slowly add retarder to the water and stir

until dispersed. Screen out any retarder lumps that may have formed. These lumps would cause soft discolored

spots in the plaster surface. Note that retarder is only dispersed in water and not dissolved, thus prolonged

standing will allow the retarder to settle out. Always stir the retarder mixture before using. Poor dispersion

increases the possibility of variable sets and soft unset spots in the plaster surface.

USG Retarder for Add directly to the mixing water prior to the addition of plaster. Once the proper amount of retarder is added,

Lime-Containing Plaster

the water should be stirred to dissolve the retarder. As little as 1 teaspoon per 50 lb. bag of lime-containing

Products

plaster will extend the setting time by 20 minutes or more.

Cleanup and Storage Clean mixing containers and tools with water immediately after use. Partially used containers should be closed

as tightly as possible. Store material in a cool, dry place. Avoid direct sunlight. Maintain temperature above

40 °F (4 °C).

Product Data Shelf Life Up to 12 months under protected storage conditions. Rotate stock.

Availability USG retarders are distributed throughout the United States. Contact a United States Gypsum

Company sales ofﬁce or sales person for additional information.

Packaging USG standard-strength retarder is available in 1.25 lb. containers. USG retarder for lime-containing

plaster products is available in 1.5 lb. containers.

Submittal Sheet

09210

USG

™

Retarders

For slowing the setting time of conventional plasters, veneer plasters, lime ﬁnish plasters and

setting-type joint compounds

– Two formulations meet a variety of setting requirements.

– Products easily disperse into mixing water for quick addition to plaster mix.

– USG

™

standard-strength retarder recommended for slight to moderate lengthening of set times of plaster

products and setting-type joint compounds.

– USG

™

retarder for lime-containing plaster products is used with conventional lime/ﬁnish plasters and DiamonD

brand veneer ﬁnish.

Summary of content (2 pages)

PAGE 1
Submittal Sheet 09210 USG Retarders ™ F or slowing the setting time of conventional plasters, veneer plasters, lime finish plasters and setting-type joint compounds – Two formulations meet a variety of setting requirements. – Products easily disperse into mixing water for quick addition to plaster mix. – USG™ standard-strength retarder recommended for slight to moderate lengthening of set times of plaster products and setting-type joint compounds.
PAGE 2
Submittal Approvals: Job Name Contractor WARNING! When mixed with water, this material hardens and becomes very hot – sometimes quickly. DO NOT attempt to make a cast enclosing any part of the body using this material. Failure to follow these instructions can cause severe burns that may require surgical removal of affected tissue or amputation of limb. Hydrated lime and sodium hydroxide are strongly alkaline. Direct contact can cause severe damage or chemical burns to the eyes and skin.