Painting in cold weather
Painting in cold weather can be fraught with issues, not only that you are cold while you are painting.
And, it is not just the weather forecast that is important if you are outside, or just ignored if you are inside. The paint might have been kept in a warm room, but what about the air temperature and the substrate temperature. It can take many, many hours to warm up a cold concrete floor that might be at about freezing point, but it takes seconds for warm paint to reach that temperature when applied. An infra-red thermometer can be cheap to get and can save a lot of time and money in the end.
Make sure that the paint is suitable for the temperatures you are working with and check up on the dew point to prevent condensation on the paint as you apply it, or before it has had time to dry.
Bear in mind also, that lowering the temperature increases the time for things to happen, so if a data sheet says that a paint is hard dry in 4hrs, make sure you know what temperature that refers to. It may then take twice as long if the temperature drops by 10'C. Not good if you have told a client he can get back to work at 0800hrs and it is still all tacky and ends up with footprints all over it.
Some other things that might happen are:
- Colour patchiness
- Paint film cracking
- Alkyd/solvent based paints can become more viscous, even becoming very thick or even semi solid.
- Water based paints may freeze or the evaporation of the water and volatile additives may be slowed down.
- Extended drying, re-coating and curing times
- Longer mixing may be required
- Water spotting and condensation issues may occur
- The paint film may not form properly and it may then turn powdery
- Being thicker, the paint will not go as far.
- As the temperature is warming and the substrate is cold, the paint can skin on the surface resulting in solvent entraption.
- If the temperature drops after work, some of the issues may occur after you have done the job and gone home. When you come back in the morning, what you see may not be what you expect.
So, although painting can be done when it is cold, there are a number of issues that should be borne in mind before starting work on a paint job in cold weather.