There are two basic types of traffic paint used primarily: waterborne and solvent based. Both can be advantageous depending on the application and each situation can dictate which one to use. All NCDOT projects must waterborne paint, while each municipality has varying specifications as to what can be used. Waterborne paint is also required when painting on a coal tar sealer. Waterborne paint has better color retention, is easily cleaned and disposal is much easier, however waterborne paint is much more susceptible to atmospheric conditions such as temperature and humidity. Waterborne paint will dry much faster than solvent based paint at higher temperatures or low humidity, but at lower temperatures or higher humidity, can take a multiple of the time needed for solvent based paint. Care must be taken when the temperatures approach the dew point, as waterborne paints will not dry when temperatures get within 5 degrees of the dew point. This is most prevalent when striping parking decks in the colder winter months. Most waterborne paints cannot be applied at temperatures below 50 degrees F, but solvent based can be applied down to 40 degrees F. For this reason, solvent based paint is much preferred in the colder months.
When applying traffic paint to new asphalt, the asphalt needs to cure about 30 days before applying the pavement markings, however in the real world, no one will ever wait this long due to the construction schedule or susceptibility of the surface to be subjected to mud or dirty conditions requiring extensive cleaning before the application of markings resulting in additional cost to the general contractor. When waterborne paints are used before the proper cure time is allowed, the paint has a tendency to lift or curl. This can be reduced by applying two thin coats of paint instead of one, but again, increasing the cost to the general contractor as most specifications call for one coat at 15 wet mils. Solvent based paints do not have the tendency to lift when applied to new asphalt, and therefore is preferred for new construction.
Care must also be taken when painting on new concrete, which also is preferred to have a 30 day cure time and any curing compound must be removed prior to application of paint.
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