Water Usage with Glass Specific Diamond Blades
A Wet Saw is a Wet Saw, is a Wet Saw...
That is, until it doesn't exactly get as wet as it should.
Diamond blades are not all made equally. Most diamond blades on the market are geared towards cutting ceramic tile, and while they may advertise the they work with glass as well, they don't actually work very well with glass. Sure they'll cut through the glass but they'll also tend to chip the edges pretty dramatically. With these types of diamond blades, they generally will have a rougher diamond in a higher concentration on the blade. They cut through the glass quickly (and poorly) and won't require much water at the contact point of the blade and glass because they are moving through the glass pretty quickly and creating very little heat buildup in the process.
The problems start showing up when you move to a more glass specific diamond blade. These blades are made specifically for giving you a great cut on your glass with little to no edge chipping. The compromise is that they will cut through glass at a slower rate and will therefore run the risk of generating more heat at the contact point of the blade and the glass. This is where it is vitally important that your wet saw is capable to supplying water to the right point on the blade for your new blade to grind through your glass correctly and efficiently.
Bad Water Placement = Bad Cuts
With the picture on the left, you can see what happens when you only have a single top down flow of water on your saw blade. More often than not, the water will travel to one side of the blade or the other and not contact the rim edge of the blade. While this saw has plenty of water flowing through it, it's all exiting the saw to the right of the blade and there is no water at all contacting the blade where it is cutting through the glass. This type of water delivery setup on your wet saw will accomplish nothing but cracking and chipping your glass and could possible damage your blade as well.
Preparation is as Important as the Final Cut
You can see now how important having a correct water flow to your blade can be when working with glass specific saw blades. It's not a lot of trouble, but making sure that your saw is capable of delivering water flow to the correct area of your blade and your glass can cut down on hours of frustration and broken glass.