The benefits of glass grinder coolants are a subject of debate within the stained glass community. Many experienced crafters use only plain water and recommend simply changing the water frequently to achieve similar results.  However, with the rising costs of hobby supplies, grinder bit longevity becomes more important, so it is worth a deeper dive into the possible benefits of grinder coolant. 

First, what is stained glass grinder coolant?  It is a lubricating additive designed to be mixed with the water in a glass grinder's reservoir to reduce friction and heat between the glass and the diamond grinding bit. This helps to extend the life of the diamond bits and can promote faster, smoother grinding. Another term for lubricating additive is surfactant. 

Surfactants (like mild soaps or detergents) are used to help water wet the glass better, allowing it to carry away glass dust (slurry) and reduce surface tension, preventing streaking and ensuring the coolant effectively cools the bit and glass, making the grinding process smoother, cleaner, and prolonging bit life. 

Purpose and Function

• Lubrication: The primary function is lubrication. The coolant acts as a buffer or surfactant, which "wets" the water, allowing it to better lubricate the diamond head and clear away fine glass particles (sludge) more efficiently than water alone.
• Heat Reduction: By reducing friction, it helps control the temperature buildup on the diamond bit and the glass being worked, which prevents overheating.
• Tool Longevity: Manufacturers claim that using the coolant can significantly increase the lifespan of your grinder bits and saw blades, with some suggesting an increase of up to 50%.
• Improved Finish: Proper lubrication and cooling can lead to a cleaner cut and a better surface finish on the ground glass edge.
• Safety: The water/coolant mixture also helps keep harmful glass dust particles out of the air. 

Composition

Most commercially available stained glass coolants, such as those made by Novacan or Glastar, are water-soluble and non-toxic formulas. They are specifically formulated for use with diamond grit tools and are generally easy to clean up with water. Always follow the manufacturer's instructions for your specific grinder model, as some manuals explicitly state to use only water. 

In summary, while grinder coolant is not required for stained glass grinding, the surfactant makes the water work better as a coolant and cleaning agent for your glass grinding. If you consider the cost of a few capfuls of coolant vs. a new diamond grinder bit, many hobbyists are choosing to invest in a coolant additive. We hope this article helps dispel the mystery around grinder coolant!