What’s the best interleaving powder for a glass fabricator to use in float glass, tempered glass, soft coat glass, and hard coat glass? What’s the best way to apply this glass separating powder?
Recently a glass fabricator contacted me asking if there’s just one interleaving powder that can be used for the wide variety of glass types and how to best go about applying it. This is a question I’ve gotten many times over the years. Here’s my response.
Interleaving powders such as those offered by Lucite and Teknapack are customized for use in the various applications you’ve described. There isn’t exactly one powder that can work for all applications if the requirement is high volume and specific. A float glass or tempering facility will specialize in a powder that works best for that application and that will be a different material than that used by a hard coat or soft coat low e-glass facility.
The powder used for float glass and tempered glass is usually a mixture of acrylic beads and acid powder such as adipic acid or boric acid. The beads provide separation and the acid is a chemical inhibitor of glass surface corrosion.
The powder used for hard coat low e glass can be either small acrylic beads or Ultra-High Molecular Weight Polyethylene (UHMWPE). These materials are most commonly used without any additives. The materials have physical properties that can tolerate the abrasive surface of the hard coating.
The powder used for soft coat low e-glass is commonly acrylic beads that are slightly compressible and very tight in size distribution. Being both compressible and close to the same size minimizes the chance that the beads will damage the soft coating.
For a fabricator with a variety of glass types, it is possible to select one powder that can work for all applications but it’s important to be mindful of limitations.
Selecting a product made from acrylic beads with no additives and having the beads be close in size is the best all-around compromise option.
If float glass and tempered glass are fabricated, packaged, and will be shipped, and/or stored in a way that minimizes exposure to high humidity or becoming wet the corrosion inhibiting acid can be eliminated. For example, if float or tempered glass is fabricated and consumed by the customer within a few days the risk of exposure to high humidity or water is much less than if the glass will be stored in an outside warehouse for many months.
For coated glass, having beads that are very close in size will work well if the powder is applied at an appropriate level. The old saying many hands make light work kind of communicates the idea. With a sufficient amount of near-size beads on the coated glass surface, the contact pressure is low and the risk of beads being damaged by a hard coating or the beads damaging a soft coating is minimized.
Teknapack offers TEK-C-47GS which is acrylic material that has been processed to remove large and small particles. The product has a mean particle size of about 125 microns.
We are also in the early stages of offering TEK-C-4F which is acrylic material that has been processed to remove large and small particles and has a mean particle size of about 75 microns.
One of these materials is probably the best option to consider for a one size fits all requirement, given the limitations I’ve described.
In regard to application methods, this too depends on the fabricating facility configuration. Float facilities and high-volume coating operations will install powder application machines above the conveyor line. These machines are fine-tuned to optimize the application rate. They cost anywhere from $40,000 – $80,000 USD depending on machine size and accessories. Many fabricators have created homegrown application methods that include modified handheld paint sprayers, salt shaker-style bottles, and even linin gloves filled with powder attached to the end of a stick. At least one of the powder machine manufacturers has offered a portable powder applicator although I don’t know if this is still available. As I recall this cost about $20,000 USD.
Generally speaking, interleaving powder/glass separating powder can replace paper or cork buttons for many applications but there are challenges and compromises to take into consideration. Paper and cork will always have a place as a reliable way to protect the fabricated glass.
Thanks for the great question and as always, feel free to contact me with any other questions.