From the Floor Up, a Blog for the Flooring Professional From the Floor Up, a Blog for the Flooring Professional

Tips of the Trade: River Rock Tile / Urethane Grout Installation

Friday, September 23, 2011
River rock, also known as pebble stone, tile installations can be difficult and requires special grouting techniques depending on the river rock material selected. The challenge is the grout joints in river rock applications often fall outside the widths/depths recommended for many types of grout, including Urethane Grout. Failure to recognize and account for this fact can lead to grout failure if proper installation techniques and the appropriate precautions are not taken.

Urethane Grouting Tips—

Before spreading grout: Stir each bucket from the bottom up just enough to mix in the skim of urethane that may be on top (by hand – preferred; drill mixer – low speed for 30 seconds; no drill mixer for glass filled grout). Do not add anything to the bucket. Stir grout periodically during installation.

Remember to seal and/or enhance any natural stone depending on your requirement. Some kind of sealing is required prior to grouting. Be sure to follow the sealer manufacturer’s cure time instructions before grouting. A good rule of thumb is to wait at least 24 hours after sealing before grouting.

While spreading grout:

Use a sponge and clean water to lightly dampen 3-5 square feet of River Rock Tile (generally not necessary on vertical surfaces).
• Float grout in using a softer-edged stone float, ensuring that all joints and spaces are tightly filled. Do not overfill as this may make grout cleanup very difficult. Grout joints must be 1/16” - 1/2” in width and at least 1/8” in depth. Joints that are deeper than 3/8” will require more cure time than typically recommended. Spread only in an area that you can reach (3-5 square foot sections typically for River Rock tile) to apply and clean urethane grout. Remove excess grout from the tile surface.
• Use a whisk broom or a block brush to knock grout from the face of the tile/stone and to smooth the areas between the stones.
• For best results, remove grout haze as you work, particularly in warm or dry climates. If working alone, only grout as far as you can reach (arm’s length) before initial cleaning. If working as a team, one person should grout, with the other(s) cleaning immediately behind the first person.
Rinse sponge in water and wring out completely. Since urethane grout requires very little water during cleanup, make sure that the sponge is wrung nearly dry. Wipe lightly, leaving sponge flat on the tile surface to prevent grout removal from joints. Excessive water during cleanup can dilute the urethane binder and cause curing issues that may lead to grout failure. Change rinse water every 100 square feet or less.

After installation:
Allow cleaned tile areas to dry, then inspect the surface. If additional haze removal is necessary, we recommend the use of Bostik® Blaze™ Urethane Grout Haze and General Purpose Cleaner. Wait 3 hours in low humidity/warm temperature (< 50% RH and > 70°F) environments and 6 hours in high humidity environments/cool temperature (> 50%RH and < 70°F) environments before using Bostik Blaze. Make sure the grout is cured enough to withstand light
finger pressure without losing form. Spray Bostik Blaze on a scrub pad designed for delicate surfaces such as the 3M™ Doodlebug™ white cleaning pad. Rub the cleaning pad lightly over the urethane haze on the tile being careful not to touch the grout joints. Note that excessive haze may require direct spray on surface, more dwell time or repeated cleaning. Do not flood the surface with cleaner. Allow Bostik Blaze to rest on the tile/stone surface for at least 60 seconds to ensure sufficient penetration. Use a damp sponge and clean water to remove the film and cleaner. Finish by drying the tile surface with a clean towel or cloth. Allow urethane grout products to cure sufficiently as follows: Light foot traffic – 24 hours; heavy foot traffic and normal cleaning – 3 days; wet areas such as showers – 7 days.


1. Use an approved waterproofing membrane such as Bostik® GoldPlus™ for mud bed applications. Be sure to follow the manufacturer’s recommendations for membrane installation. Apply to within 1” of any drains to prevent weep hole blockage. The use of pre-sloped, waterproof trays (instead of mud beds) is highly recommended.
2. Do not use urethane grout to re-grout commercial and wet areas such as showers, steam showers, and outdoor applications. On traditional shower floors apply a waterproof membrane such as Bostik GoldPlus over sand/mud bed to keep hydration from slowing or stopping full grout cure.
3. Protect outdoor applications by tenting the grouted area at least 1 foot above surface for 7 days.
4. It is not recommended to grout or clean tile if the tile surface temperature is above 90°F (32°C). If this is the case, wait for the tile surface to cool prior to grouting or cleaning. You may accelerate the tile cooling process by wiping with a damp sponge. Be careful not to add excessive water during the tile cooling process.

Need more help? Contact our Technical Service group at 1-800-7/BOSTIK.

Visit Bostik at the 2011 National Hardware Show

Thursday, March 31, 2011

Well, it is hard to believe another year has come and gone, but the 2011 National Hardware Show ( is just around the corner - May 10-12, 2011 at the Las Vegas Convention Center.

I am very excited that we will be exhibiting at the show again this year since there will be more than 18,000 buyers and retailers attending. We
will be showing off our entire line up of consumer products, including hardwood adhesives and accessories and urethane grout. A major focus will be on our new woodworking lubricant products GlideCote™ and BladeCote™. These two innovative products, which have primarily been used exclusively among professional woodworkers, is now available to the consumer with the following features and benefits:


• Eliminates “hang-ups
” on sliding surfaces.

• Protects all tools an
d equipment from rust.

• Contains no silicone or petroleum oil. Will not stain wood or interfere with glues or finishes.

• Perfect for table saw beds, drill presses, lathes, planers, band saws, miters, panel saws, and all hand tools.

• Prevents resin build-up. Reduces blade cleanings.

• Works equally well on steel or carbide, stellite and diamond-tipped cutting blades.

• Extends overall life of blades and bits.

• Contains no silicone or petroleum oil. Will not stain wood or interfere with glues or finishes.

Stop by our booth #4126.

This Old House Uses TruColor Pre-Mixed Grout!

Monday, January 18, 2010


Tune into THIS OLD HOUSE on PBS on Wednesday, January 27th at 8:00 p.m. to see tile contractor Mark Ferrante install and grout a subway tile backsplash using "a new pre-mixed urethane grout that promises faster installation time, greater stain resistance, and no additional sealing." The grout he's using? TruColor PreMixed Grout, of course!

You can also pick up the latest issue of This Old House magazine,
hitting t
he stands January 18th, to see TruColor PreMixed Grout used as the grout of choice for installing a glass mosaic backsplash, featured in "Weekend Remodel". You can also see this feature Weekend Remodel on the This Old House website

Installing Glass Tile

Monday, December 28, 2009
Glass tile installations have become very popular and are a growing market share. Glass tiles are ecologically sound (many glass tile are made from recycled glass) and offer a wide range of colors.

The key to achieving a good installation is substrate preparation. Substrate preparation is the #1 factor that accounts for the success or failure of an installation. Surfaces need to be clean, level and stable. It is highly recommended to use a waterproofing/crack isolation membrane prior to installing glass tiles to prevent shrinkage or movement in the substrate. We suggest Hydroment Gold, a Latex-Based Anti-Fracture and Waterproofing Membrane.

It is imperative to install all glass tiles with a quality white latex-fortified Portland cement thin set, as this will have the least affect on the color and transparency of the tiles. Some suggestions include Hydroment StoneWall High Performance-Non Sag Mortar or Hydroment ReFlex Ultra Premium Latex-Modified Thin Set Mortar. Never use any multi-purpose or regular thin set mortars or any type of mastic as this will may result in failure. To install the glass tiles, skim coat the substrate with the thin set using the flat side of the trowel then use the proper notch side of the trowel to install the tile. Press the tiles into the thin set ensuring that the back of the tiles are completely coated and flat.

After the thin set has cured, you are ready to start grouting. We suggest the use of Bostik's TruColor Pre-Mixed Urethane Grout. TruColor is excellent for glass tiles, offers the ultimate in color consistency, crack resistance and stain protection, TruColor never needs to be sealed! TruColor is a clean as you go product so we suggest you grout as far as you can reach (10-12 square foot area). Clean and rinse sponge in water and wring nearly dry. Please read installation directions for all products used to be assured of a successful installation.

The Sound Truth about Wood Flooring and Accoustical Systems

Tuesday, August 18, 2009
Many residents in multi-family construction and high rise condominiums would like to replace carpeting with wood flooring. However such installations are concerning due to condominium requirements and building codes relating to noise which may transfer to neighbors down stairs.

Fortunately there are several ways to meet or exceed local codes and not violate your condominium association rules.

The most common material used for this purpose is cork. Typically 1⁄4” cork underlayment installed beneath wood flooring is provides sufficient acoustical dampening to meet all requirements. Bostik sells both 1⁄4” and 1⁄2” cork underlayment which may be glued to concrete subfloors using any of Bostik’s Urethane adhesives. Once the cork is installed, wood flooring is bonded directly over the cork underlayment with a Bostik Urethane adhesive.

The cork system is popular and proven. However installation of cork prior to the flooring adds considerable labor, materials cost and elevation. So, as an alternative to cork Bostik manufactures MVP4 which is a liquid applied urethane membrane with good acoustical dampening properties. MVP4 is simply applied with a notched trowel the afternoon before installation of wood flooring. It is a quick, easy process that does not add any appreciable elevation to the project.

There are various acoustical systems on the market. Most of which are compatible with with Bostik Urethane adhesives. For more information call Bostik Technical Service at 800 523 6530

LEED Silver hospital -are there any useful suggestions that will safeguard this installation from potential failure for at least 10 years?

Wednesday, July 29, 2009
Prior to installing 50,000 square feet of recycled rubber flooring on the concrete slab of my client’s new LEED Silver hospital, are there any useful suggestions that will safeguard this installation from potential failure for at least 10 years?

The number one thing to do prior to the installation of virtually any floor covering on a concrete slab is to test for the presence of elevated moisture vapor emission or pH levels.
It is essential to install a moisture vapor barrier coating if either of these conditions is above industry standards, but also a wise step to take as a precautionary measure to avoid potential problems in the future. Perhaps the greatest reason floor covering installations fail today is due to the breakdown of the adhesives used due to elevated levels of either condition.

The most robust moisture vapor barrier coatings for the installation of rubber flooring are made of epoxy resins and are a great preventive measure for any installation, regardless of size. Bostik is a global leader in the sale of moisture vapor emission control systems and has a choice of two-component coatings available. Bostik’s Durabond D-250 Moisture Vapor Barrier Coating and D-261 Extreme Moisture Vapor Barrier Coating are both high performance, roller-applied, epoxy coatings that meet LEED credit MR 4.2 Low-Emitting Materials – Paints & Coatings. Both coatings have VOC contents well below the 100 g/L LEED limit for this category of waterproofing sealers. These coatings have minimal odor, dry rapidly and contain Bostik’s Blockade™ antimicrobial protection. Either coating can be used in conjunction with Bostik’s complete line of Durabond installation materials that include cement repair patches, self-leveling underlayments and adhesives. In fact, when used as part of a complete Bostik system, the installation can be warranted for a period of 10 years.

Controlling Moisture Vapor in Concrete Prior to Gluing Down Wood Flooring

Monday, July 13, 2009
All concrete surfaces regardless of age or grade level will release some level of moisture vapor. Vapor retarders such as Bostik's MVP4 Moisture Vapor Protection has been extremely effective in controlling the rate of vapor transmission from the subfloor when used in conjunction with any approved Bostik Urethane Adhesive. Bostik’s MVP4, being the first one-part, polyurethane product in the market, currently is the only vapor protection product that does not require moisture testing prior to use and also does not have an upper limit! Once your concrete substrate is properly prepared, MVP4 is easily troweled on using a 3/16" x 5/32" V-Notch trowel and has virtually no odor. After a short cure time of 12 hours, you can begin installing solid or engineered wood flooring using Bostik's Best, TKO, BSTurethane or EFA+.