Latest News

Kazakhstan Float Glass Advances

As the process technology provider of the Orda Glass float glass manufacturing and processing plant in Kyzylorda, Kazakhstan, Stewart Engineers, Inc. is pleased to announce that installation of production equipment support steel structures is advancing.

The installation crew on site in Kyzylorda, under the supervision of Stewart Engineers, is ramping up the installation of support steel structures for the tin bath and melting furnace of the Kyzylorda float glass plant.

Support steel installation commenced in early March. Nearly 80% of the support steel installation is expected to be complete as early as July, at which time sufficient steel will be in place to begin installation of the melting furnace and tin bath, which comprise the heart of the float glass production line. It is critical, however, that a new construction company be appointed shortly to continue the civil works, as the melting furnace and tin bath cannot be installed until civil construction is sufficiently advanced. The batch plant (for mixing of glass-forming ingredients) must also be completed in order to commence heat up of the melting furnace.

“Stewart Engineers is delighted that work continues and we applaud the efforts of our partner Orda Glass Ltd. LLP in searching for a new civil works construction company to fulfill Orda’s civil works responsibilities” advised Stewart Engineers’ Vice President of Technology, Chris Cording. “Stewart Engineers is assisting Orda in this initiative. China Triumph International Engineering, a well-known float glass factory construction company is currently in negotiations to take over the civil works from the previous contractor ShymkentKhimMontazh.”

CVD vs. Sputter


The two primary methods of depositing coatings on glass are Physical Vapor Deposition (PVD) and Chemical Vapor Deposition (CVD). Magnetron sputtering is the most common PVD process. Sputtered coatings are generally referred to as “soft-coat” because they are “painted on” by ionized metals directed at the glass. CVD coatings are referred to as “hard-coat” because they are burned onto the glass and become part of the structure. These coatings can be harder than the glass itself and boost chemical resistance. Both types of coating offer advantages and disadvantages. When evaluating the best option for a glass manufacturing facility, coating performance and ease of fabrication are important factors.

Magnetron Sputtered Technology
Sputtered coatings are applied independently of the float glass manufacturing process (“off-line”). Thin films are formed by accelerating high energy ions from targets toward the glass surface at low temperatures. The ions bombard the glass surface forming uniform thin layers. The bond is weak, causing a “soft coating” that is more easily scratched or damaged and chemically fragile.

Commercial sputtered coatings are applied in a vacuum chamber and typically consist of 6-12 layers of thin metallic and oxide coatings. Silver is the active layer for “Low E” (low emissivity) sputtered coatings. Remaining layers include barriers, color modification oxide layers, and sacrificial metal layers. Sputter manufactures use these additional layers to offer more products than pyrolytic producers offer.

Offline sputtered soft-coating offers a few benefits:

  1. Sputtering can be done by companies not involved in glass production.
  2. Sputtering is a well-established process with a broad range of target materials.
  3. Short delivery times are possible with less inventory per product.
  4. Sputtered coatings can offer better properties for some applications.

Many companies embrace sputter coating for the advantages listed above. Glass distributors only coating choice is to install sputter systems, which accounts for their popularity. However, glass manufacturers have other options and should consider the disadvantages of sputter coating listed below:

  1. Capital costs are higher for sputtering equipment relative to production capacity.
  2. Manufacturing costs are high due to materials, energy, maintenance, and depreciation (often 2 to 3 times the price of CVD coatings), resulting in low margins.
  3. Production yields decline as more layers are deposited.
  4. Sputtered coatings are soft and are damaged more easily during normal handling and fabrication.
  5. Sputtered coatings are sensitive to moisture requiring sealed bags with desiccant.
  6. Shelf life is limited in sealed packaging, but is further reduced after packaging is opened.
  7. Sputtered coatings have weak adhesion which can cause sealant failures in insulated glass units.  Edge deletion of sputtered coatings is recommended which adds manufacturing costs.  Sputtered coatings that “don’t require edge deletion” can experience rapid seal failure due to certain detergents and brick washes.
  8. Sputtered coatings cannot typically be used with single pane applications.
  9. Tempering soft coat requires unusual skill, and  usually results in increased tempering losses.

Pyrolytic CVD Technology
Chemical Vapor Deposition (CVD) can produce a variety of aesthetic and functional coatings. Chemical vapors are brought to the hot glass surface with specialized coaters during glass manufacturing. The vapors react with the hot glass (600°C to 700°C) and form a covalent bond. This results in a hard and robust coating that enhances the strength and stain resistance of the glass. Fragile sputtered soft-coatings can be accidently wiped off during normal handling. Manufacturers and fabricators handle CVD coatings with the same procedures and equipment as standard float glass resulting in higher yields, higher profit, excellent lead times, and improved customer service.

Typical Single Flow CVD Coater

Pyrolytic CVD coatings offer several benefits:

  1. Lower capital investment.
  2. Higher yields.
  3. Lower manufacturing cost.  CVD coatings cost ~$1/m2 vs. Sputter coatings ~$4/m2.
  4. CVD is an on-line process, resulting in unmatched throughput.
  5. CVD coatings are bonded to the glass with covalent bonds, resulting in increased shelf life, scratch resistance, and stain resistance.
  6. CVD coatings can be used in specialty applications like monolithic, touch screen, and anti-microbial. Conductive coating applications, like solar panels and appliance glass, are much more practical with CVD coatings.
  7. Special handling equipment and procedures are not needed; glass is handled and shipped with the same equipment as base glass.
  8. CVD coatings are not susceptible to delamination caused by moisture in the air, resulting in an unlimited shelf life.
  9. CVD glass is tempered similarly to standard float glass products, resulting in improved throughput and cost effectiveness.
  10. There is no visual differentiation between annealed or tempered CVD products. Projects requiring a mix of tempered and annealed glass benefit from a more pleasing uniform color.

While possessing several benefits from a production standpoint, CVD is not as widely used as sputtering for the following reasons:

  1. Until recently, CVD technology, for on-line use, was not readily available on attractive commercial terms. Stewart Engineers is now your source for “state of the art” CVD coating systems.
  2. CVD systems must be installed on-line at a float glass manufacturing facility, either at a new build or a retro-fit.
  3. Some manufacturers mistakenly believe CVD cannot be installed due to space constraints. Most float baths will accommodate an on-line CVD system.
  4. Some manufacturers mistakenly believe CVD can only be installed during a cold repair.

Which is best?
For a glass manufacturer, which type of coated glass is best depends on a number of factors, including where customers are located, the size and type of operation, inventory turns, desired durability, etc. However, for most glass manufacturers, pyrolytic CVD technology is superior due to lower capital cost, lower operating cost, and higher throughput.

For downstream customers, both sputter coated and pyrolytic glass are viewed as high-performance glass products. Architects and building owners are generally open to using both products and are primarily concerned with aesthetics which slightly favors CVD. For further information regarding Stewart Engineers’ world class AcuraCoat® Pyrolytic CVD Technology please contact us at

30 Year Anniversary

It all began in 1986, when Mr. Leslie T. Stewart CEO embarked on a journey to develop control systems to support the glass industry.  Stewart Engineers was founded in Grosse Ile, Michigan.  For several years, they served local clients in the control system industry.  As the team worked closely with these clients, they saw more and more business opportunities in the glass industry.  This led to an expansion in their team for the development of float innovative technology specifically for the float glass industry.

Early in the 1990’s, Stewart Engineers designed its first StewartFloat® Tin Bath Furnace.  The first StewartFloat® was installed and successfully commissioned in Indonesia.  Towards the end of that project Andrew Stewart, now President of Stewart Engineers, signed on to work for the company as a Controls System Engineer.

Leslie T. Stewart




Andrew Stewart



After successfully commissioning over 20 StewartFloat® Tin Bath Furnaces, Andrew Stewart relocated the office and all its employees to Wake Forest, North Carolina. Andrew then led the design of the AcuraCoat® On-Line chemical vapor deposition (CVD) glass coating system and was promoted to President of Stewart Engineers.  He has steered the team in the successful commission of 3 turnkey glass manufacturing facilities, over 20 custom StewartFloat® Tin Bath Furnaces, 5 AcuraCoat® on-line glass coating systems, and over 100 other glass industry related projects.

Our latest world class turn-key glass manufacturing project is ORDA Glass, located in Kyzylorda, Kazakhstan.

ORDA Glass Complex Manufacturing Capabilities:

  •     600 MTPD
  •     2-12 mm glass thickness
  •     Producing export quality architectural glass
  •     CVD coated glass products:
    •         Low E
    •         Sunlite
    •         Solar control

Orda Glass


Stewart Engineers is the Technology Provider and Partner, EPC Contractor, Project Manager, and responsible for all product guarantees. The ORDA Glass complex will be ready for production in 2017 and is expected to be the most technically advanced glass complex in the world.
Stewart Engineers is a leader in the Glass Industry and has a presence on nearly every continent.  The growth of Stewart Engineers in this challenging economy is largely due to the investments in innovative technology advancements, the authority to provide technology licensing, all while offering the highest quality products at competitive prices.

Stewart Engineers would like to take this opportunity to express its appreciation to all clients, suppliers, and business partners for their continued support and commitments over the years.  We look forward to new opportunities and continuing to work in this great industry.

Orda Glass Construction Update 4/13/2016

The construction of the Orda Glass float glass manufacturing facility in Kyzylorda, Kazakhstan is making dynamic progress.

With all of the engineering complete and the warehouse erection nearly finished, the site team is moving activities to the process buildings. The civil works are moving along at a productive steady pace. Our project managers, engineers, and construction team have assured the timely completion of the project while maintaining the highest quality. In addition, all the process suppliers are actively procuring the process equipment. It is anticipated that the first shipments of process equipment will start arriving in Kyzylorda in summer of 2016.

The Orda Glass Plant is projected to be completed in the Spring of 2017.NorthEast View 2