What the difference is between a small and long crack?

To put it simply, the primary difference is that one is subsurface and the other surface.  

Subsurface cracks usually refer to the initial impact point where a rock or hard projectile hits the windshield and creates a small circle-like crack.  

It looks something like the one pictured in this image:

You’ve probably seen this before and experience a sudden bang on your windshield, only to see this happen in an instant.  

Once you have fixed a few of these, you’ll notice that they are usually around 1 inch in diameter and the cracks reside below the surface of the windshield.    

Over time, this cone shaped crack will eventually turn into what’s called, a long crack if not taken care of.  Micro-cracks will weaken and spread /extend due to stress and vibrations of the vehicle.

This leads to a surface crack, which means that it is now exposed to the top layer of the glass whereas the initial impact point is not.  

In the image below, you’ll see that the cracks are extending longer than an inch past the original core impact point.

How can you check if it’s a subsurface or surface crack?

The easiest and quickest way is to use something flat and fine edged like a razor blade and run it along the top of the crack.  If you can feel an uneven bump on the surface, this will indicate that that' it’s a surface crack that has to be repaired in a slightly different manner than if it were a subsurface one.

Our training videos and guide will show you how to fix both types of cracks with Clearshield’s Windshield repair kits.