Standard Gypsum Retarder
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For slowing the setting time of conventional plasters, veneer plasters,
lime finish plasters and setting-type joint compounds.
· Easy
to use – they are dispersed in mixing water for additional to plaster
mix.
· Standard Gypsum Retarder is recommended for slight to
moderate lengthening of set times of plaster products and setting-type joint
compounds. |
| Description |
- Retarder is an additive that slow or lengthen the setting time of
gypsum plaster. Retarder is added to the plaster in specific amounts
during the manufacture to provide a setting time that meets product
and job needs. Standard 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.
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| Limitations |
- Excessive additions of retarder will drastically reduce the 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 evaporated.
- Retarder 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.
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| Directions |
- Applications General – Prior to use of any additive, good job
practices involves mixing a trial batch of formulated product and determining
the set time. Once the set time is known, a measured amount or Retarder/water
mixture is added to adjust the set. Any available container (wax cup,
coffee can, measuring cup) can be used to measure the retarder/water
mixture. Also, it is a good practice to always keep the mixing equipment
clean between batches to prevent quick-setting action from occurring
in subsequent mixes.
- Application Standard Retarder - Retarder should be mixed with water
before adding to plaster. Mix one teaspoon of dry retarder with five
fluid ounces of water to prepare a solution that will extend the set
time of 100 pound of gypsum plaster by 30-40 minutes or more. For larger
quantities, mix and entire 1 ¼ lb container of Standard Retarder
with 5 gallons of water in a convenient size container to prepare the
retarder solution. Slowly add retarder to the water and stir until the
retarder is dispersed. Screen out any retarder lumps that may have formed.
These lumps will cause soft discolored spots in the plaster surface.
Not 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.
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| Cleanup and storage |
- Clean mixing container 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 directly sunlight. Maintain temperature
about 40oF (4oC).
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Technical Support Hotline: 212-367-7561 |
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