UV glass bonding offers niche opportunity for fabricators
The art of glass bonding has hundreds of uses in glass construction and provides fabricators with another niche to help grow their business. By utilizing the latest innovations in adhesives, fixation devices, ultraviolet lamps and hardware, as well as proper training and technical assistance, fabricators can create store displays, showcases and furniture designs without the usual mechanical fasteners, moving toward the clean transparent look of UV-bonded components. Today’s advanced UV adhesives provide strong bonds to many different substrates, so glass can be bonded to different materials including steel, aluminum, stainless steel, ceramic, stone, wood and plastic. For example, with glass bonding, you can apply glass shelves to mirrors, bond glass table tops to metal posts, attach door handles to glass doors, and bond metal hinges and locks to glass cabinets.
Bonding glass with UV-curing adhesives can easily be achieved by following these basic steps.
1. Material selection
The selection of glass and adhesive is critical to the results because different choices result in varying bond strengths. Although clear float glass, mirrored, tempered and smooth flat wired glass can be easily bonded, structured glass, such as patterned, sandblasted or wired glass can cause lower bond strengths or cannot be bonded at all. The UVA light permeability depends on the glass thickness and color intensity. Glass with high UV absorption, such as laminated or colored, cannot be bonded with common UV adhesives and requires a highly sensitive adhesive. Bonding metal to glass also requires a suitable adhesive. The manufacturer/supplier can assist you with the proper choices of adhesives.
2. Surface preparation
Wear Nitrile or latex gloves to keep all bonding surfaces clean, free of grease and dry. Use appropriate cleaners free of surfactants such as soap or other contaminants. In most cases, common glass cleaners are not suitable. All parts to be bonded must be at room temperature to obtain a stable and durable bond. Heating all surfaces to 155 degrees Fahrenheit (68 degrees Centigrade) prior to bonding will remove any condensation that could adversely affect the bond strength.
3. Adhesive selection and application
The technological development of UV glass bonding has created a range of adhesive choices with unique design, performance and processing benefits. These amazing materials have properties that allow them to remain in a liquid state during proper storage, and are able to later cure with UV light exposure in a matter of seconds. UV adhesives are available in high, medium and low viscosity forms, in both clear and colored versions. Some are best suited for glass-to-glass bonding, some for glass-to-metal bonding, and others for laminated glass. Choose your UV adhesive according to the bonding materials, the application of the finished product, and the resulting stress load. When adhering towel bars or shelves, choose a high viscosity, 100 percent solid general purpose adhesive that forms resilient, high-strength bonds between materials such as glass, steel, aluminum, stainless steel and many plastics. It’s best to source all the supplies and tools needed for your glass bonding from a highly dependable single source who can recommend the products best suited for each application.
4. Applying UV adhesive
Before applying the adhesive, check to see if the bonding parts fit in their intended position. One way to do this is to assemble the project without bonding by using fixation devices to hold the surfaces in position. When ready to apply adhesive, be sure to heat the parts first, within five minutes of application. If possible, the bonding surfaces should be in a horizontal position when the adhesive is applied. The smoother the bonding surface and the thinner the layer of adhesive, the stronger and more resilient the bond will be, so use the manufacturer’s dispensing systems and application needles. Medium/high viscosity adhesives should be applied in a “wiggly” pattern before the parts are joined. Bonding parts should be evenly and carefully joined to avoid trapping air bubbles. When bonding metal to glass, a liberal amount of adhesive should be applied to the center of the part and gently squeezed or clamped to eliminate air bubbles. A low-viscosity adhesive seeps into the bond line gap by itself and therefore can be applied after the bonding parts are joined in their final position. When applying the adhesive after joining the parts, the project should be built one step at a time. To achieve distribution over the entire bonding surface, the parts should be slightly lifted and lowered to increase coverage before curing. Low-viscosity adhered joints are heated together after pre-assembly, and then UV adhesive is applied. The heat gun can be aimed around all the fixation devices, allowing the heat to warm the entire joint area.
5. Structural stability
It is critical that the bonded surfaces are kept in a stable and fixed position, and that is where the fixation devices come in. There are a variety of fixtures available to suit each particular application and provide high-precision positioning of the assembly parts. These include adjustable suction holders, angle clamps, adjustable and fixed 90-degree inside and outside suction holders, pump-activated suction holders and corner clamps for bonding surfaces in a wide range of angles.
6. Curing UV adhesive
When curing UV adhesives, wear safety glasses that have UV filters. Use a suitable UV curing lamp that is not shorter than the bonding edge to avoid tension build-up due to uneven curing. A wide variety of curing lamps are available. There are hand-held lamps and battery-operated versions, as well as curing tube lamps and high-intensity LED lamps. Position the lamp as close as possible, and do not move the parts during the curing process. Pre-cure by exposing to UV light from 10 seconds to two minutes, depending on type of lamp and thickness of glass. The fixation device should be removed and any adhesive residue cleaned. Then expose to the UV light for at least 60 seconds to five minutes. Twenty-four hours after this final UV exposure, the bond will be fully cured and can then be put under load.
7. Bond test
The final step is to test the strength of the bond by subjecting it to stresses exceeding those it would normally incur by impacts, tilting and sudden movements. As mentioned earlier, it is always a good idea to order bonding adhesives, fixtures, lamps and other accessories through a single source. A larger supplier also will have an array of glass furniture hardware such as hinges, locks and latches, knobs, shelf supports, furniture feet and casters, and table legs, posts and base plates. You should also work with a source that provides training and technical assistance. In-house seminars, instructional videos and Webinars are always helpful. On-call technical assistance is invaluable. Although this article summarizes the basic bonding process, there are many choices to be made in adhesives, curing lamps, fixation devices and other elements. An experienced technical expert can help address your particular needs and walk you through the ordering process. One thing is definite - with the proper training and equipment, glass bonding can be a fun, creative, additional source of projects, income and happy customers.
Read a related article on how the team at Elite Glass & Mirror, Las Vegas, used UV glass bonding technology to create display cubes for a priceless collection of Chinese artifacts at the Khotan restaurant in the Treasure Island Resort Casino.
View a photo gallery documenting the Elite Glass & Mirror team's experience.