Molten Aura Labs Introduces SANDCRAFTED® Borosilicate Colors
Our unique glass colors start as crystalline quartz silica. That silica gets combined with high-purity chemicals, then melted into glass at temperatures exceeding 3000 degrees Fahrenheit. Samples of each formula are tested at The Orton Materials Testing and Research Center for exact strain point, annealing point, and CTE (Coefficient of Thermal Expansion).
Every element we use in the glass affects it’s working characteristics in some way. Having complete control over the composition allows us to minimize undesirable traits while maximizing color saturation and usability. No color is ever going to work exactly like clear. However, we go to great lengths to ensure that the balance of CTE and viscosity ensures compatibility with the NIST Borosilicate standard (3.3 x 10-60).
Why make borosilicate colors from scratch?
Simply put, we wanted stronger colors without sacrificing compatibility. To us, the industry standard process of buying clear glass, grinding it into powder, and adding small amounts of colorants seems outdated and inflexible. Clear borosilicate is essentially 81% Silica, 13% Boron, 4% Alkali, 2% Alumina. As soon as you add anything to the clear cullet to colorize it, you alter the ratio, changing its workability. Trying to create saturated colors using pre-made glass as a base presents far too many limitations.
If you are familiar with painting and the process of mixing colors, then you know that a color can never get any more saturated than it is “straight from the tube”, so to speak. As soon as you mix a color with any other color, it loses intensity. A painter has the luxury of starting with extremely saturated colors, allowing for the maximum range of hue, saturation, and value in the final work. In a similar way, we want to give glass artists a deeper toolset to choose from. Our colors are designed to be layered over or under clear, applied over white or Moonstone, vac-stacked, blown-in, or used at full-strength.
In addition to enhanced saturation levels, we are able to improve the working properties, stabilize the colors that are typically unstable, and minimize, if not eliminate, surface issues.
Our vision is to propel a new generation of borosilicate artwork forward with the richness and optical clarity that has been a staple in soft glass for centuries. We see SANDCRAFTED® glass as the logical next frontier for discerning borosilicate artists.
We know that CTE doesn’t tell the full story about compatibility, but it is a good starting point. The viscosity of the glass, particularly within it’s cooling temperature range, is a huge factor as well. This is where a polariscope becomes an essential tool for the modern glassmaker (and glassblower!). You can use a small piece of polarized film and use your cellphone’s white screen as the light source (most phone displays emit polarized light). This will work for you in a pinch if you don’t have access to a laboratory grade polariscope.