SILCOR® Fast Set Primer Data Sheet

Two component, low viscosity urethane primer for sprayable primer use with Silcor 900MP only.

Product Description

SILCOR® Fast Set Primer is a two-component fast curing, short recoat time urethane primer for concrete substrates specifically designed for the SILCOR® 900MP liquid waterproofing membranes.

Product Advantages

  • Fast curing with short recoat time : Minimum 20 minute recoat time at 70°F (21°C)
  • Easy to apply by spray or roller or brush
  • Convenient for large size jobs (10 gallon kit)
  • Simple mix ratio (1:1 ratio by volume)
  • Excellent adhesion exceeds concrete cohesive strength
  • Can be applied easily from 40°F to 100°F (4-38°C)
  • Can be applied over wood, concrete and steel after relevant prep of substrates


1. Surface Preparation

  • Minimum pull-off adhesion strength of the concrete substrate as determined by ASTM D4541 or ASTM D7234 shall be115 psi for limited access roofs and 215 psi for vehicular trafficked decks. Where these values are not achieved by pull-off adhesion testing, remove all laitance by shot blasting.
  • Surfaces must be clean, sound, free of dust, laitance, sealers, grease or any other contaminants that might reduce adhesion.
  • If power washing the substrate, allow sufficient time for the residual humidity to dissipate. The substrate moisture content before application of the primer must be less than 5%. The primer surface before application of SILCOR® 900MP liquid membrane must be clean and dry.

2. Mixing

  • Store SILCOR® Fast Set Primer in a dry and cool place out of direct sunlight.
  • Add the complete quantity of the B-component to the A-component to assure correct mixing ratio.
  • Mix with a slow turning mixer (less than 300 rpm) for 3 minutes in order to obtain a homogeneous mixture.

3. Application

  • The application temperature range is 40°F to 100°F. Higher temperatures reduce the pot-life considerably.
  • Apply SILCOR® Fast Set Primer to the surface by brush or roller immediately after mixing ensuring coverage of the entire surface.
  • Pour the primer onto the surface in a zigzag pattern.
  • After pouring onto the surface, distribute the primer evenly with foam rubber squeegees and roll using Perlon rollers.
  • The primer should be evenly distributed at 10 mils thickness with complete coverage of the surface.
  • If the surface is very porous and absorbs primer to the extent that open surface remains additional primer must be added in this area within the pot life or recoat time of the primer.

4. Curing

  • The SILCOR® 900MP membrane should be applied within 24 hours. This window is influenced by ambient temperature and humidity. When this time is exceeded before the membrane is applied, re-apply a new layer of SILCOR® Fast Set Primer.

Recoat Times

  • SILCOR® Fast Set Primer has excellent wetting and soaks into the concrete surface, tack free time is not a good indicator for recoat time. GCP recommends recoat time with adhesion strength testing according to ASTM D4541.
Ambient & Substrate Temperature Minimum Recoat Time
95°F (35°C) 10 minutes
70°F (21°C) 20 minutes
40°F (4°C) 30 minutes

5. Cleaning

  • Mixing and application equipment should be cleaned immediately with mineral spirits. Remove hardened material mechanically. All solvents should be used only in accordance with manufacturer’s recommendations. Do not use solvents to clean hands or skin.


SILCOR® Fast Set Primer Part A 5 gal (iso)
SILCOR® Fast Set Primer Part B 5 gal (resin)

Typical Properties

Solid Contents 96.4% ASTM D2369
Working Time, cup, 70°F (21°C) 20 minutes
Concrete Adhesion 1,000 psi (6.9 MPa) or substrate failure ASTM D4541
Steel Adhesion 1,000 psi (6.9 MPa) or substrate failure ASTM D4541
Mix Ratio (by Volume) 1:1


Approximately 192 ft2/gal (1,920 sqft/10 gallon kit), actual will vary depending on the absorption and profile of the surface.


SILCOR® Fast Set Primer should be stored and shipped in clean, dry, low-humidity, and shaded or covered environments in original sealed containers between 50°F (10°C) and 90°F (32°C). Shelf life is 1 year in unopened containers stored under the conditions described above.

Health and Safety

Read the product label and Safety Data Sheets (SDS) (SDS A) (SDS B) before use. SDSs can be obtained from GCP Applied Technologies. | North America Customer Service: +1 (877) 423 6491

We hope the information here will be helpful. It is based on data and knowledge considered to be true and accurate, and is offered for consideration, investigation and verification by the user, but we do not warrant the results to be obtained. Please read all statements, recommendations, and suggestions in conjunction with our conditions of sale, which apply to all goods supplied by us. No statement, recommendation, or suggestion is intended for any use that would infringe any patent, copyright, or other third party right.

SILCOR is a trademark, which may be registered in the United States and/or other countries, of GCP Applied Technologies Inc. This trademark list has been compiled using available published information as of the publication date and may not accurately reflect current trademark ownership or status.

© 2021 GCP Applied Technologies Inc. All rights reserved

GCP Applied Technologies Inc., 2325 Lakeview Parkway, Suite 475, Alpharetta, GA 30009, USA
GCP Canada, Inc., 294 Clements Road, West, Ajax, Ontario, Canada L1S 3C6
This document is only current as of the last updated date stated below and is valid only for use in the United States. It is important that you always refer to the currently available information at the URL below to provide the most current product information at the time of use. Additional literature such as Contractor Manuals, Technical Bulletins, Detail Drawings and detailing recommendations and other relevant documents are also available on Information found on other websites must not be relied upon, as they may not be up-to-date or applicable to the conditions in your location and we do not accept any responsibility for their content. If there are any conflicts or if you need more information, please contact GCP Customer Service.

Last Updated: 2024-06-21