Is the old saying of holding your thumb up to the windscreen to prevent breakage from a stone true?

Is the old saying of holding your thumb up to the windscreen to prevent breakage from a stone true?

There is an old saying that suggests holding your thumb up to the windscreen can prevent breakage from a stone. But is there any truth to this claim? Let's examine the science behind it.

Firstly, it is important to understand how windshields are made. Modern windshields are typically constructed using laminated glass, which consists of two layers of glass with a layer of polyvinyl butyral (PVB) sandwiched in between. This design provides strength and durability to the windshield.

When a stone or any other object hits the windshield, the impact energy is distributed across the surface of the glass. The PVB layer helps to absorb and disperse the energy, preventing the glass from shattering. This is why windshields are designed to withstand small impacts without breaking.

The old saying suggests that holding your thumb up to the windscreen can somehow redirect the trajectory of a stone, preventing it from hitting the glass directly. However, there is no scientific evidence to support this claim. The size and speed of the stone, as well as the angle at which it hits the windshield, are the primary factors that determine whether the glass will break or not.

While holding your thumb up to the windscreen may create a psychological sense of protection, it is unlikely to have any significant impact on the outcome. The force of a stone hitting the windshield is often too powerful to be influenced by the presence of a thumb.

It is worth noting that there are other effective ways to prevent windshield damage from stones. Maintaining a safe distance from other vehicles, especially trucks and construction vehicles, can reduce the likelihood of stones being thrown up onto your windshield. Additionally, avoiding gravel roads and driving at a moderate speed can help minimize the risk of stone impacts.

In conclusion, the old saying of holding your thumb up to the windscreen to prevent breakage from a stone does not have any scientific basis. While it may provide a sense of reassurance, it is unlikely to offer any real protection against stone impacts. It is always best to focus on safe driving practices and take necessary precautions to minimize the risk of windshield damage.