Like acrylic sealers, the solvent-based urethanes are more durable and more chemically resistant than the water-based urethanes. However, both types of urethanes require detailed attention to the concrete. The concrete surface should have as close to a neutral pH as possible, and the concrete needs to be totally dry, John says.
"The water-based is the most important to get to a neutral base. The solvent-based are a little more tolerant, but it's still important," John says.
Polyureas are a relatively new technology in the decorative concrete industry. These quick-setting sealers are easy to apply and are becoming more popular, but they also come at a higher cost, Thome says. "They're starting to put them on concrete countertops because it is a small scale where cost per square foot really doesn't matter. You're looking at long-term durability in that respect," he says. "But when you're talking about a 5,000- or 6,000-square-foot floor, now the cost becomes a little bit more important."
So contractors who are doing larger projects may want to consider what the cost would be before choosing a polyurea sealer.
Cure and seals
Another option for contractors is to choose a cure and seal product. These products help accelerate the curing of concrete while providing a seal at the same time, Asmuth says. Cure and seals also help increase the density of the concrete, which improves the concrete's strength.
Cure and seals are good if a contractor wants the concrete to cure faster. It also provides contractors with a shorter wait when applying a second sealer over the concrete, which is a common practice Asmuth suggests. "It's an extra step, but it can help reduce problems, especially with sealers that may be of a lower quality," he says.
However, cure and seals either should be avoided or removed if a reactive penetrating sealer, epoxy or urethane will be applied in the future. There are some dissipating cure and seals which can be easily removed for these situations, John says.
So which one?
Equipped with knowledge of the types of sealers available, the next step is the big one: how to choose the best sealer for the job. The characteristics of each sealer are a good starting point. But other considerations are involved. Below are factors to consider when picking a sealer:
- Customer preference/requests
- Environment - type of facility, indoor or outdoor, ambient temperature, weather conditions, etc.
- Level of maintenance customer prefers
- Time between resealing
- Final color
- Cost - although this should not be the determining factor
- Ease of application
- How consistent the sealer is across the application
- How the sealer cures
Remember, the customer is boss. If the customer leaves the choice up to the contractor, always make sure the customer understands the sealer choice and how it will affect the concrete. "Always do a mockup. And maybe show the customer a couple of different types before you go and apply," John says. "Have the customer approve it and then continue."
Asmuth suggests finding a sealer that works for different applications. Most decorative concrete contractors do multiple types of decorative work. Finding a sealer that can work on all or most of those applications can help make a contractor's sealer choice easier.
Finally, once you find a sealer that works for you, keep it. "Every environment is different. If it works in your environment keep on using it; don't change," Thome says.
This isn't to say that a contractor should never try different sealers. But if you find one that works for your jobs and in your climate, make it easier on yourself and stick with it.