Anthony Wells, Marketing Manager for Industry at Sika Limited

Often people are amazed when they hear that the only thing holding the windscreen to their car is some adhesive and a clip on rubber gasket. It’s actually the best technology for this particular application, but how does it affect you as a driver?

What is Keeping the Windscreen on my Car?

Traditionally windscreens are held in place with an adhesive called urethane. These urethanes possess different properties making them cure at different rates. The cure rate of the urethane depends on weather conditions (temperature and humidity) and type of urethane used during the replacement. Technology has developed quickly over the years with curing rates becoming faster. Last year Sika launched PowerCure, an adhesive that fully cures within 60 minutes.

Safety

In most vehicles, the passenger side air bag uses the windscreen to direct the air bag at the passenger. If the urethane is not cured when this occurs, the windscreen can end up on the ground which reduces its effectiveness. In an accident where multiple areas of the car receive an impact, the windscreen improves the cars rigidity, which in turn reduces the amount of damage caused. Many people have the perception that glass and adhesives are not the strongest of materials, however the windscreen now accounts for up to 30 percent of a car’s torsional rigidity. Ultimately the windscreen plays a big part on safety.

 

One of the questions that you need to ask the person replacing your windscreen is “what is the safe drive away time?” Safe Drive Away Time (SDAT) is the amount of time an adhesive requires to reach the level of strength necessary to safely hold a windscreen in place in the event of a crash.  

Does SDAT Mean The Adhesive Has Fully Cured?

Not necessarily, although the vehicle is deemed safe, the bead of adhesive will take longer to cure, in some cases 24 hours. There are technologies such as Sika PowerCure that will fully cure in 1 hour; it all depends on what product is used.