Virgin vs. Recycled Glass Interleaving Paper


Watch out for added chemicals in your paper! Glass manufacturers should be aware that if their paper is not produced specifically for glass interleaving, the paper mill can add chemicals to the paper at any point. Typical paper mills will often incorporate chemicals to decrease cost and increase efficiency assuming that the paper they are producing will go into flexible packaging and other specialty applications. Silicone based defoamers are one example of this.

In paper manufacturing, silicone-based defoamer agents can decrease cost and are therefore gaining in popularity. Unless the paper mill producing your paper is custom manufacturing a glass interleaving paper specifically for this application, they are likely to maximize efficiency without regard for how chemical changes can impact glass products.

In fact, one of our current customers first came to us with a defect that was happening for months. Our laboratory analyzed the defect and determined that there was a thin coating of silicone on every window. As it turned out, the paper mill had switched to a silicone defoamer with the goal of decreasing their cost. The glass defect was costing hundreds of thousands of dollars annually. This customer switched to Flexsheen® and has not had an interleaving-related defect since.

No Chemical Controls with Recycled Paper

It may seem obvious, but no chemical controls are possible with recycled paper. Regardless of the level of cleaning, recycling facilities are not able to remove 100% of the dirt and debris. Moreover, recycled pulp mills are not able to wash out all of the impurities. Therefore, glass interleaving paper must be 100% virgin.

While this may seem cut and dry, specifying 100% virgin paper can be confusing. This is because in some segments of the paper market, industry standards all manufacturers to use up to 20% recycled pulp and still label their paper as “virgin”. Therefore, glass manufacturers should specify that their paper be made with “100% virgin cellulose fibers”.

Learn More by Downloading Our White Paper

The range of glass interleaving papers available is as varied as the level of knowledge regarding their use. With this in mind, our free white paper discusses the factors that allow a paper to effectively interleave glass:

  • Uncontrollable and controllable factors in glass interleaving
    • Moisture
    •  pH
    •  Resin
    • Ambient heat
  • Added chemicals like silicone-based defoamer agents

Download our free white paper to learn more about the factors to consider when selecting glass interleaving paper for your application!

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