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Moisture Tolerant Smoothing Compound

SX250 is a pre-smoothing and repair compound for clean, sound, porous substrates.

SX250 is specifically designed for preparation of interior applications and can be applied by hand or by pump.

  • Suitable for use below a damp proof membrane
  • High compressive strength for heavy traffic applications
  • Shrinkage compensated
  • Can be mixed with clean aggregate
  • Protein free

Moisture Testing

(in accordance with British Standards 8203)

  • Suitable for application on substrates with <75 % RH.
  • It is recommended that a moisture test is conducted prior to the application of SX250. For further details or to arrange for a moisture test please contact tremco illbruck Technical Services.


  • Ensure all surfaces to be coated are clean, dry, frost free and free from grease, oil, dirt, dust, loose friable material and any other contaminants (coating, laitance, etc.).
  • Heavy shot blasting; scabbling or floor planing is recommended.
  • Any surface hardener or curing compounds should be thoroughly removed prior to the application of SX250. For full details of surface preparation contact tremco illbruck Technical Services.


Use CS175 Epoxy Primer for Porous Substrates as a primer in all cases. See separate data sheet for application. When using SX250, the CS175 should be allowed to dry and overlaid within 24 hours.


Mix by hand or using an electric drill and paddle. Add 4 litres of water to the mixing vessel and add the 25 kg of SX250 powder while mixing to ensure a smooth flowing consistency ensuring all particles are well mixed. Do not add additional water as this will reduce the performance of the final screed.


Material should be trowelled smooth before the application of a TREMCO surface membrane.

For full application information, refer to product data sheet or contact tremco illbruck customer services on 01942 251400

Technical data

CompositionA blend of special cements, graded
fillers and modified polymers
Open Time/Workability
(at +20°C)
up to 25 minutes
Pot Life
(at 20°C)
20 minutes
Compressive Strength1 day 18.33 N/mm²
7 days 33.70 N/mm²
28 days 42.84 N/mm²
Tensile Strength1 hour 1.67 N/mm²
7 days 2.98 N/mm²
28 days 4.16 N/mm²
CoverageApproximately 5 m² per 25 kg sack at 3 mm thickness
Cure Time
(at 20°C)
Between 2 - 4 hours for foot traffic and 8 - 12 hours
for application of damp proof membrane, floor covering
and loading
StorageStore in dry, shaded conditions between +5°C and +35°C
Shelf Life6 months when stored as recommended in original unopened packaging
High temperatures and humidity will lead to a reduced shelf life

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