* Please read the article Survey of Sealer Options for Concrete Countertops before reading this article.

Introduction

Stain-resistant concrete countertops are here! The Concrete Countertop Institute (CCI) created stain-resistant, acid-resistant, heat-resistant and abrasion-resistant concrete countertops using a urethane-based sealing system from RJSC.

This article explains tests that CCI performed using specific topical sealing products: a 2-part water-based urethane, which is applied over a 2-part epoxy primer, which is applied over an organo-silane surface conditioner that enhances bond. This complex combination of chemicals resulted in a very high-performance surface.

The effort and skill required to apply these products was considerable, but it resulted in excellent performance over time.

Overview of the Steps

This system is manufactured by RJSC The steps and detailed instructions below come from those 2 companies.

1. Apply surface conditioner (O-S/W, a water-borne organo-silane)
2. Apply epoxy primer (StoneLok E3, a water-borne 2-part 51% solids epoxy)
3. Apply urethane top coat (StoneLok 2K, a water-dilutable 2-part polyurethane available in Gloss, Low Gloss and Xtra Low Gloss)

Click here for RJSC's instruction overview document. Note: You must use the StoneLok E3 to achieve the performance results detailed in this article. If you take the option of skipping this step as mentioned in the overview document, you will not get the same stain resistance.

Detailed Instructions

In our tests, we followed the manufacturer's instructions. Please note that The Concrete Countertop Institute (CCI) does not manufacture or sell these products. They are subject to RJSC's limited warranty. While CCI has tested the products on its own concrete formulation, it is impossible to test in all possible situations, and therefore we cannot accept any liability for performance of these products. 

We can say that you must follow all instructions exactly and practice to get good results! Download and read each of the information/instruction sheets below, and PRACTICE!

You will find the staff at RJSC to be very knowledgable and helpful, and able to make recommendations for your specific situation. They will even test a sample of your concrete free of charge!

• Apply surface conditioner according to manufacturer's instructions (O/S-W, a water-borne organo-silane)
  • O-S/W Data Sheet
  • O-S/W Directions
• Apply epoxy primer according to manufacturer's instructions (StoneLok E3, a water-borne 2-part 51% solids epoxy)
  • StoneLok E3 Data Sheet
  • StoneLok E3 Directions
  • StoneLok E3 Special notes over acid stain
  • StoneLok E3 Post application care
• Apply urethane top coat according to manufacturer's instructions (StoneLok 2K, a water-dilutable 2-part polyurethane available in Gloss, Low Gloss and Xtra Low Gloss)
  • StoneLok 2K Data Sheet
  • StoneLok 2K Directions (directions for any quantity)
  • StoneLok 2K Directions (directions for 12oz quantity included in kit)
  • StoneLok 2K Directions for hot weather (over 85 degrees F)
  • StoneLok 2K Post application care

Performance

This system is an advanced urethane-based system. As mentioned in the article Survey of Sealer Options for Concrete Countertops, urethanes commonly require a primer, as is the case with this system. This system also utilizes a surface conditioner, in this case an organo-silane used before applying the epoxy primer coat. Overall, however, the performance of the system exhibits the "pros and cons" described for urethanes in the article Survey of Sealer Options for Concrete Countertops.

While this system involves three stages, the first is simple and fast. The organo-silane surface conditioner ensures a good chemical bond with the concrete, essential for long-term reliability and performance. Application is simple: brush on and let dry. There is no surface film or residue, so streaking or bubbles are not an issue.

The second and third stages are the primer and sealer. Both are water based so thinning and cleanup are very easy, and involve no expensive or hazardous chemicals. Application can be by rolling or by spraying.

The Concrete Countertop Institute tests on concrete sealed with this system demonstrated very good stain resistance and a high quality surface finish. Concrete samples were first treated with the OS/W surface conditioner, then primed with the epoxy primer, and then sealed with one coat of the StoneLok 2K urethane (S2K).

The Xtra Low Gloss version was tested. While not matte or dead flat, the Xtra Low Gloss had a pleasantly soft sheen that enhanced the surface color without looking shiny or plasticky. The film thickness of both the primer and sealer were estimated to be on the order of 5 to 10 mils or so - very thin.

Stain tests demonstrated excellent performance:

• When left on for 24 hours, vinegar, red wine, oil, beer, cola, ketchup and rubbing alcohol did nothing. No marks, discoloration or sheen change.
• Water did not penetrate at all.
• Mustard did discolor the sealer (but not the concrete) when left on for 24 hours, but bleach eliminated the spot.
• When left on for 24 hours, bleach did dull the sealer, but 1 hour of exposure didn't do anything at all.

Heat tests were also very successful. A 1/4" thick steel plate was heated in a toaster oven set on broil. It sat in the oven for 20 minutes before being placed directly on a sample of sealed concrete. The steel plate was allowed to cool to room temperature before being inspected. No damage, discoloration or change of any kind was detected.

This sealer has demonstrated excellent bonding characteristics, both to the concrete and to itself. Peel tests performed by first scoring the sealer with a razor and then ripping duct tape applied over the cuts did not peel any of the sealer off the concrete, testament to its excellent bond.

When one coat of the S2K sealer was applied over month-old sealer with no surface preparation (other than cleaning with water), the reapplied sealer passed the peel test with no peeling or debonding. This indicates that repairs can be made with confidence and without extensive surface preparation.

Where to Get It

This system is available as a kit from the manufacturer, RJSC. RJSC is a research and development company specifically for the study of cementitious substrates and surface defects. They both manufacture a variety of concrete sealing products of their own, as well as carry other manufacturers' products. The products described in this article are manufactured by Richard James Specialty Chemicals Corporation, which is where the detailed instruction sheets come from.

RJSC's goal is to provide superior products and recommend others of high quality when their own products are not suitable for the job. They don't just sell sealers; they solve problems. RJSC welcomes your questions about this sealing system, and can provide you with expert technical support. Contact:

Bob Chatterton
607-655-2362 (direct) or 800-475-1975 (main office)
bob@surface519.com
www.rjsconline.com

RJSC sells this system as a complete kit, in a small quantity that is affordable and gives you an opportunity to learn and test the system. When ordering, refer to the "Counter Top Test Kit". If you decide to use the system for all your countertops, you may later order larger quantities of each product at a savings per unit price.

* EXCLUSIVE BENEFIT for Concrete Connections Members! Members receive 5% off all orders of O-S/W, StoneLok E3 and StoneLok 2K! RJSC supports Concrete Connections' goal of providing the latest and greatest concrete countertop information, and believes that the better-educated their customers are, the more successful everyone will be. RJSC has teamed with The Concrete Countertop Institute to offer this exclusive benefit and encourage concrete countertop professionals to Get in the Know. Click here for Concrete Connections membership information. Members may find details about how to get their discount here.