The Architect’s Viewpoint – Part IV
The Architect’s Viewpoint: Specifying the Right Floor—Part IV
By Andy Bowman
Here is the final installment of this four-part article. Parts I to III were published in the three previous issues of Concrete Openings and focused on the selection and preparation of the appropriate flooring system. Please refer to the Archives page to view online.
Floor System Troubleshooting
They occur due to a difference in surface tension between the coating and the substrate. This can be the result of a contaminant (oil, grease, dust, sealers, etc.), amine blush, primer outside the recoat window, moisture, etc. In most cases, good surface preparation will solve the problem. To verify if the problem is substrate or product related, mix a small amount of the material and apply to a sealed surface outside of the project environment. If this does not “fish eye,” you know the problem is on the substrate. If this also fish eyes, stop coating and call your product supplier.
To stop fish eyes, you can add 1-2 pounds of 325 mesh silica flour, per mixed gallon of pigmented epoxy. The silica flour can only be mixed in (dispersed) with a drill mixer. This can slightly change the color so be consistent. This is not a substitute for proper surface preparation. Do not add silica flour into a clear epoxy topcoat, as it will cloud or opaque the coating.
Air bubbles come from a variety of factors. Typically, if the problem is in the material, bubbles will occur uniformly and within 30 minutes of application. This can be the result of the product, temperature, mixing or application technique.
Check substrate and product temperature. The thicker the film and lower the temperature, the more difficult it is for the resin to release air. The addition of silica flour, as mentioned above for fish eyes, will stop air bubbles if they are product or mixing related. Have an air release additive on hand for all coating application, as a precaution.
Substrate out-gassing is difficult to predict or anticipate. Priming or coating late in the day, as the slab temperature is falling, is a good practice. These bubbles occur late in the cure, often after the contractor has gone. The product is no longer fluid and will not flow back to close the hole. They appear as small craters, with raised edges. To repair, they must be sanded smooth and the hole filled prior to coating or they will reappear.
This phenomenon is common. The name refers to the curing agent/ hardener, which is an amine. It can and will react with moisture and carbon dioxide in the air to form the blush. Dependent upon the formulation, it is most likely to occur at low temperatures or high humidity and is worse when in combination. Many novolac epoxies will blush in ideal conditions. The blush should be visible as a film or haze on the surface that reduces gloss. It is noticeable by touch. It can be removed by a warm water detergent scrub, solvent or mechanical abrasion (sanding). A blush can also be an indication of improper mix ratio or an incomplete mixing.
Color Change/Pigment Float
Epoxies by chemistry are not color stable. If you do a project in phases, with the same batch # of material, you can anticipate a slight shade differential at the tie-in. Use only one batch # of topcoat, if you have more than one batch #, box the material.
Plan your project to minimize the time between mix-to-mix tie-ins. This is formulation and temperature dependent but a good rule is: try not to go beyond 20 minutes. Do not roll into a partially cured edge. Use joints or other natural breaks to minimize the time between mixes. If you cut-in too far out in front, you will need to re-roll over this material to avoid a shade differential.
Special color requests are more likely to have a pigment flotation issue than standard colors. It can be more pronounced in dark/deep blues, browns and greens.
Having the flooring system installation tools will minimize problems and the need to possibly redo a job.
- Spiked shoes – Those back rolling will need to walk in wet material.
- Silica flour
- Loop rollers – For self-leveling coating applications of more than 12-15 milliliters. They leave no roller fuzz nor do they impart air. If utilized in a thin film, they will leave texture.
- Porcupine rollers – To remove air bubbles, while the material is still wet.
- Mil Gauges – To insure thickness and coverage rates.
- Infrared Thermometer – Do not leave home without it.
- Dew Point/Humidity Meter (Psychrometer)
- Air Release Additive
- Adhesive roller covers are great to back roll with but can be hard to find. Some Home Depot and Sherwin-Williams stores do carry them. They shed almost no roller fuzz/lint. They should only be used to back roll as they hold little material and must be kept full to avoid whipping air into the coating.
Ongoing Maintenance and Protection of the Flooring System
Seamless floors are based upon a chemical reaction, which converts the fluid-applied flooring material into a strong and durable solid floor. Just as in the chemistry lab or in the kitchen, the chemical reaction will be affected by temperature, moisture and other contaminants. Therefore, throughout the curing process and before placing the floor into service, the flooring system must be protected from both environmental and physical damage.
- Maintain ambient and substrate temperature, moisture, humidity, ventilation and other conditions of rooms where work occurs. The facility temperature and humidity must be measured and maintained 72 hours prior to and throughout the installation period.
- Do not install materials until building is permanently enclosed and wet construction is complete, dry and cured.
- Prevent dust and airborne contaminants from entering the uncured resin.
- Immediately after application, it is important to keep traffic and debris off the surface until the coating is fully cured (18 – 24 hours @ 77 degrees Fahrenheit), unless otherwise stated by the manufacturer.
- Allow the resinous flooring system to cure for 24 – 48 hours prior to covering to protect from damage and wear during the construction operation.
- Cover flooring with a breathable material such as cardboard, carpet padding or Kraft paper. Do not cover with plastic.
- Cover this breathable material with 6-millimeter (0.25-inch) thick hardboard, drywall, plywood or particleboard. Tape edges to prevent movement in areas where foot or vehicle traffic, rolling of fixed scaffolding and overhead work occurs.
- Do not allow the protection of the underlying finished flooring system to be exposed to water or other moisture during the construction period.
Allow all decorative epoxy topcoats to cure for five to seven days prior to applying water or exposing to chemicals.
DO NOT leave cleaning solutions or water puddle on floor, especially on fresh coating (three to seven days), as discoloration may occur. Follow Detergent Manufacturer’s Cleaning Instructions.