Tristar Glass, Inc.'s spandrel lines give our clients the ability to create exciting new looks that increase aesthetic appeal and building performance. Coatings are available in both a ceramic frit and ICD Coating’s OPACICOAT-300®.
Spandrel glass is glass that has been rendered near opaque by coating, hiding the utilities and control areas of a building, typically found between the occupancy floors or as wall cladding. The process of rendering this glass opaque takes place by passing clean glass through a roller coating machine that transfers a coating onto the surface of the glass. The coating is either a silicone based paint ICD Opaci-Coat 300 or ceramic frit. The ceramic frit must be fired onto the surface of the glass during the heat treatment process, creating a permanent bond to the glass surface. This production process, while 'state-of-the-art", produces a spandrel area quality product. There are and will be, inconsistencies. When either of these products are placed in a spandrel area cavity on the number four surface and the back lighting in the cavity is eliminated the inconsistencies inherit to the product wash out. Neither product is meant to be used in a vision area application.
Spandrel glass must be heat-strengthened or fully tempered. Tristar Glass Products supports the industry standards concerning the use of fully tempered glass. In other words, fully tempered glass should only be used when and where necessary. These areas are defined as areas where safety glazing characteristics are required by code and for high wind load areas where both annealed and/ or heat-strengthened glass will not meet the appropriate project design wind loads.
Ceramic frit or ICD Opaci-Coat 300 should be installed in applications that do not allow viewing of the glass in transmission. A uniform colored insulation or back-pan should be placed at a minimum distance of 1" behind the spandrel glass to eliminate the possibility of read-through. Spandrel glass is never meant to be used in a vision area. Spandrel areas should never be backlit or installed in a manner that allows daylight or artificial light on the opposite side.
Glass types with high visible light transmittance or low visible reflectance tend to show more contrast between vision areas and spandrel areas than do glass types with lower visible light transmittance and high reflectivity. This contrast can be further minimized by maintaining a consistent construction between the spandrel and vision insulated glass units in regards to the exterior glass color and coating.
Ceramic Frit vs. ICD Opaci-Coat 300:
Both ceramic frit and Opaci-coat have outstanding records of durability and long-term performance. In most applications, the products are equivalently matched and either would satisfy project requirements at a comparable cost. However, there are certain applications in which the slight differences between the two products qualify one as a superior choice. Many of these differences are outlines in the "Applications and Limitations" sections found in the next two pages. In all cases, the two products should not be mixed on a project without fully understanding the implications/impact this could have on the exterior appearance of the building.
Please visit our resource page for installation instruction and guidelines.
For information on proper cleaning, storage and handling of spandrel glass, refer to the Glass Association of North America (GANA) glass information bulletins: "Proper Procedures for Cleaning Architectural Glass Products" and "Construction Site Protection and Maintenance of Architectural Glass"
Choosing a surface:
Please be advised that the preferred placement of ceramic frit or Opaci-Coat 3000 in a spandrel area IGU is on the number four surface versus that of the number three surface.
Due to the high temperatures experienced in spandrel much attention is paid to achieving the best possible primary IGU seal. This is to ensure the longevity of the unit. We know from experience that the best possible seal is achieved with sealant to glass contact. With ceramic frit placed on the third surface you end up with sealant to ceramic frit contact in lieu of sealant to glass contact. When placing Opaci-Coat 300 on the third surface the outer perimeter of the coating must be edge deleted to allow for proper adhesion of the spaced PIB to the surface of the glass. By relocating the ceramic frit or Opaci-Coat 300 coatings to the number four surface the desired sealant to glass conract is achieved, allowing for the best possible performance of the unit over its life time.
In addition, ceramic frit or Opaci-Coat 300 located on the number four surface serves to minimize the difference in appearance between vision and spandrel areas. In a vision area, light is both transmitted and reflected through both an outboard and inboard lite of glass creating an appearance of depth from the project exterior. When you locate a ceramic frit or Opaci-COat 300 coating on the number three surface you lose this appearance of depth. This is caused by light transmitting and reflecting through only one lite of glass. When viewed from the project exterior, the result is spandrel area glass appearing more noticeable in comparison to the vision area glass.