After moisture, the concrete surface temperature along with the air temperature causes the most amount of problems when applying sealers to decorative concrete.
The surface temperature is usually the most important to consider.
After applying a sealer it goes through a chemical reaction that causes it to cure and form a film.
Extreme hot or cold temperatures will cause the sealer to dry too fast or too slow.
The best range of temperature is 50 to 80 degrees F. That 30 degree window isn't very big, especially when working outside in the summer months.
It is very important to check the weather when sealing concrete, here is what can happen if the temperature is too low or high.
All sealers have a minimum temperature they need to dry properly. For most sealers this is around 40 - 45 degrees.
Most sealer manufactures recommend 50 degrees for a minimum. If the temperature is below 40 degrees you risk the sealer not completely drying.
This weakens the sealer and it usually doesn't last very long before it starts to fail.
If the temperature is extremely cold you will notice a white powder left by the sealer after its solvent or water content evaporates.
As the temperature increases the speed of the chemical reaction (drying time) of the sealer increases also.
The faster the sealer drys the less time it has to lay out evenly on the concrete surface and form its film.
High temperatures make it difficult to roll out sealers efficiently, the sealer usually starts sticking to the roller causing a stringy effect and leaving roller lint behind.
Spraying solvent based sealers is recommended when the temperature rises because it is much faster.
Always have a backup sprayer ready in case the first one breaks or plugs up.
A common problem caused by high temperatures is the formation of bubbles or blisters in the sealer as it drys out. The solvent drys too fast trapping air and gas in the sealer.
Because of strict VOC requirements, higher solvents are being used in concrete sealers. This makes planning your time to apply sealers very important.
Try sealing concrete in the early morning or early evening for best results.
For information on other related concrete sealer topics click on the links below.
CONCRETE SEALER AND CONDENSATION PROBLEMS
DEICING SALTS AND CONCRETE SEALER PROBLEMS
WHAT CAUSES SEALER BLISTERS AND BUBBLES?
SEALER SURFACE PREPARATION BEFORE SEALING
IS THERE A TINTED SEALER I CAN USE?
WHAT KIND OF SEALER APPLICATOR SHOULD I USE?