Terms of the deal were not disclosed.
Global Security Glazing makes ballistics-grade security glass as well as other glass and glazing products for a variety of applications, the two companies said in a statement.
The company is expected to develop new products and to buy related companies as a result of the acquisition, said Beth Lesniak, vice president of Grey Mountain. The company's glass products are in demand to help make government buildings more safe and secure as well as to help with energy efficiency, Lesniak said.
Global Security Glazing's products also provide fire resistant protection to buildings and vehicles. Prisons, embassies and armored vehicles are a few of the areas where the products have been used in the past.
Grey Mountain Partners most commonly invests in middle-market companies with enterprise values between $30 million and $150 million.