Top-Surface Retarder

Product Description

TOP-CAST is a water-based, top-surface retarder which does not require covering with plastic for protection. It is available in 12 depths of etch, each one color and number coded for safety and convenience.

Product Advantages

  • Comprehensive range of etch depths
  • Excellent depth of etch control
  • Color coded products
  • Heavily pigmented for ease of application
  • Excellent coverage rates
  • Solvent free, odorless
  • Heat resistance up to 150°F (65°C)

Product Uses

Ideal for poured-in-place flatwork and the top surface of precast panels. The wide selection of grades available provides a comprehensive range of effects, from a simulated light acid wash or sand blast finish up to full exposure of 1 1⁄4 in. (32 mm) aggregate.


Each product grade creates a unique degree of reaction to produce the desired effect on the surface mortar. The retarding chemicals diffuse into the paste during the first hours of curing and slow down the cement hydration reaction. During the next 16+ hours of curing the bulk concrete hardens, except where the cement matrix has been retarded. The retarded surface can then be removed by water or pressurized water, revealing the aggregate in the concrete mix.

Application Information

Always prepare small test panels to determine the most suitable grade to obtain the desired depth of etch. When pouring test samples, always simulate job site conditions as well as mix designs to be used on the project to establish the proper grade selection and procedures.


In preparation for pouring of concrete, protect all curbs, borders, adjacent stones, pavers, etc. with a coat of TOP-CAST® SS-100 surface protectant. Allow coating to dry before pouring concrete. Pour concrete and float or trowel finish. Alternatively, screed away excess water, and hand seed extra stone into top surface, if desired. Finish with a Darby trowel to keep concrete pores open for surface retarder application.

Mix TOP-CAST thoroughly before application. Apply TOP-CAST ® surface retarder uniformly to the wet concrete after the initial bleed water rises to the surface. Spray with a low-pressure sprayer (plastic preferred) until the surface has a complete hiding coat. Do not apply too sparingly. Use water for clean up. Once dry (1-2 hours after application), TOP-CAST® provides good protection against intermittent rain and does not require additional cover.


Wash off with high-pressure water. Actual removal time for the desired appearance varies based upon concrete mix design, finishing technique, weather conditions and grade of TOP-CAST used. The retarded cement matrix can be removed as early as 4 hours and up to 16 hours depending on conditions. Complete your project with one of the products from the TOP-CAST® decorative finish system.

Coverage Rates

TOP-CAST surface retarder will cover approximately 200–300 ft /gal (4.9–7.4 m /L).

TOP-CAST® Grade Guide

Light Acid Wash 01 White
Acid Etch 03 Light Violet
Sand Blast 05 Powder Blue Violet
Up to 1/4 in. (Up to 6.5 mm) 15 Yellow
1/8 to 1/4 in. (3.0 to 6.5 mm) 25 Beige
1/8 to 3/8 in. (3.0 to 9.5 mm) 50 Canary Green
1/8 to 3/8 in. (3.0 to 9.5 mm) 75 Blue
3/8 to 1/2 in. (9.5 to 13 mm) 100 Gray
3/8 to 5/8 in. (13 to 16 mm) 125 Pink
3/8 to 5/8 in. (13 to 16 mm) 150 Green
5/8 to 1 in. (16 to 25 mm) 200 Salmon
1 to 3/2 in. (25 to 38 mm) 250 Orange

*564 lbs/yd3 or 355 kg/m3 of cement.

Packaging & Handling

TOP-CAST® surface retarder is available in 5 gal (19 L) plastic containers.


TOP-CAST® surface retarder has a shelf life of two years from date of manufacture in closed original containers.

Store out of direct sunlight and between 50°F and 90°F. Do not allow to freeze.

All precautions defined on the SDS (Safety Data Sheet) for Top-Cast must be followed. | North America customer service: 1-877-4AD-MIX (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.

TOP-CAST 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.

© Copyright 2019 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 Canada. 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