After investing a great deal of time and effort into your countertop project, you want the last step to go smoothly. You may not realize that there are differences between successfully sealing indoor countertops and sealing outdoor countertops but there are and here to tell us all about it is Shawna Turner, General Manager for Direct Colors.
Amie Nolen: Welcome, Shawna.
Shawna Turner: Thank you.
AN: So this seems like it might be a big deal. Why should folks sealing outdoor countertops be concerned or take extra care during application?
ST: Absolutely right. It is a big deal that could become a costly and irritating problem, fortunately, with some careful preparation, one that is completely avoidable. Outdoor countertops need special consideration during sealing because unlike indoor tops, they’re outside and exposed to temperatures and direct sunlight. As long as temperature and sun exposure can be controlled for before and during the application, the sealer should go down properly.
AN: What can a homeowner do to create the ideal application conditions?
ST: The first step would be to put a tarp up around the countertop 24 hours prior to sealing to prevent contact with direct sunlight. Concrete in direct sunlight can be as much as 30 degrees hotter than shaded concrete and darkly colored concrete can be even hotter. No sealer can be applied successfully to concrete that hot. For best results, place a flat thermometer on the countertop, cover with a towel and read after 5 minutes. Repeat elsewhere on the surface. Every reading should be 75F or less to begin sealing. Ideally the ambient temperature should be no higher than 85F as well.
AN: What happens if the countertop surface is hotter than 75F?
ST: When you apply a countertop sealer to hot concrete, small air bubbles are very likely appear either during the application or just after. The air bubbles are formed by air rising through the concrete and becoming trapped in the sealer. The bubbles will eventually collapse leaving unattractive concave spots behind. The only way to correct this problem is to sand and apply again. Nobody wants to do that if it can be avoided.
The best time of day for sealing outdoor countertops is when it is cooling or contracting rather than expanding. As the day heats up, so does the concrete and air begins to pass through the surface. When temperatures are cooling, the concrete contracts is therefore a better candidate for sealing. My recommendation would be to seal the concrete when it is at its lowest temperature of the day. Depending on where the countertop is located, that could be very early in the morning or late in the evening.
AN: What sealer do you recommend most frequently for outdoor use?
ST: I probably recommend the 500 Solvent Based Polyurethane most commonly for outdoor use. It’s our most durable and chemical-resistant product. I also think it’s easier to apply and of course, the odor is less of a problem outside. Our 550 Water Based Polyurethane can also be used outdoors if preferred. Polyurethanes should be expected to last about 5 years outdoors depending in part on weather conditions and use. The 100% Epoxy is NOT intended for use outside for any reason.
AN: Is there anything that can be done to extend the life of a sealer on an outdoor countertop?
ST: There are a few things. First I’d recommend listening to our podcast, Care and Maintenance for Countertop Sealers, for more information on how to wisely take care of countertop sealers over time. Second, for our listeners in a cold weather climate, cover your outdoor countertops with a tarp in the winter to protect it from winter precipitation. It will make a big difference how long the sealer lasts. Customers living in extremely hot climates, especially in the desert, should expect direct sunlight to degrade their sealer more quickly unless the countertops can be shielded from the sun as much as possible.
AN: Thanks for the great preemptive outdoor sealing advice. I’m sure many mistakes will be avoided after listening to this podcast. For more information on concrete countertop projects indoors or out, visit our blog at www.directcolors.com. If you’d like a free design consultation tailored to your project, send us pictures and a description by email or call us at 877-255-2656. We’re ready to help!