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The Process of Tempering Glass

Tempered glass, or heat strengthened glass, is glass that has been heat-treated to make it stronger, more resistant to heat and break in a way to prevent injury. The first patent on a whole process to make tempered glass was held by chemist Rudolph A. Seiden who was born in 1900 in Austria and immigrated to the United States in 1935

Today, tempered glass is made all over the world including at our OEM & Distribution facility in Neenah. How does annealed glass become tempered glass? We’ll take you through the steps.

Step 1: Pick The Glass. We have sheets and sheets of glass that are 8 feet by 11 feet.  We can store more than 1,000 sheets of glass in our warehouse at time. The thickness ranges from 5/32 to 1/2 inch. We have everything from clear glass to frosted glass to clear mirror.

Step 2: Cut the Glass into the Desired Shape.  The sheet of glass gets move by a machine and placed on the CNC Cutting Machine. The CNC machine is programmed to cut the desired shape. Afterwards, the employee breaks the excess glass manually.

This has to be done before the glass is tempered, as the tempering process will weaken the glass if it is cut or etched afterward and may increase the likelihood of breakage.

Step 3: Seaming Machine, Glass Edger, CNC Mill or Water jet. Depending on the type of order, the sheet of glass can go several different ways either to the seaming machine, glass edger, CNC mill or water jet.

The seaming machine is used to take the sharp edge off of the glass. The glass edger creates a ground  or high polish on the edge of the glass. The CNC Mill is used to make or edge custom and DOT patterns. It can cut, seam, or even high polish shapes and holes. Like drilling, milling uses a rotating cylindrical cutting tool. Abrasive water jet cutting technology is a great method for cutting glass because it allows for contours and shapes that cannot be achieved or achieved easily with other cutting machines at a reasonable cost. 

Step 4: High Speed Washer. This removes any tiny grains of glass deposited during the other processes, as well as any dirt that may interfere with the tempering process.

Step 5: Heat the glass in the tempering oven. The oven reaches temperatures of over 600 degrees Celsius (1,112 degrees Fahrenheit), with the industry standard being 620 degrees Celsius (1,148 degrees Fahrenheit). The temperatures changes depending on the thickness of the glass, color of the glass or even the temperature outside. The tempering process takes about 2-25 minutes.

Step 6: Quench the glass to cool it. The heated glass is subjected to seconds or minutes of high-pressure blasts of air at various angles. The rapid cooling causes the outer surfaces of the glass to cool and contract faster than the center, giving the tempered glass its strength.

Step 7: Label, Package & Delivery. The glass is off to the customer.  

Omni OEM Glass Fabrication’s understanding of current industry trends, fabrication, fit, and finish allow us to provide innovative new products, designed and manufactured right here in the USA.

Call Us Today! 1.800.236.7887


I just spoke with Dave V. by phone, but wanted to be sure that my appreciation did not go unnoticed. Jeff and Mark of your residential division just left my home after spending two days replacing several storm damaged windows.  I am calling and writing to express my deep appreciation for their professionalism, expertise and spirit.  They are both an asset to your company.  With a positive experience like the one I have experienced, you can bet that if there is additional work that I need done, Omni will be my first call.   ~ Thom N. Oshkosh, WI

“Mark and Brandon are going great guns here. Thanks for sending these gentlemen to do our installation. I have a GREAT deal of confidence in them and fully expect the entire job to go as well as it has to this point.”-Jim

“Your residential installer was wonderful and did an amazing job.”-Kyle, Green Lake

“Both Steve Bridwell & Mark Willems did a great job of helping me with my patio door after my home invasion.”-Kathy, Oshkosh

I wanted you to know that Mark Willems our installer did a FANTASTIC job. He is very professional, knowledgeable and personable. He represents your company well. P.S. We have made several referrals based on our experience! -Mike & Mary Kay, Winneconne

My recent experience with Omni Glass & Paint was fantastic. I had been waiting 3 months for a part for our front door from another glass company in Oshkosh. I reached out to Omni Glass & Paint; they came to look at the door, found the part and installed the part in less than a day. The door works perfect now. I was so impressed with Omni’s work and would highly recommend them to anyone. – Matt Bakalars, Fox Valley Savings Bank

Mark and Jeff installed windows in our home in Oshkosh.  We were extremely happy with their work but more than that, they went above and beyond to install those windows and were extremely friendly and informative along the way.  They even found an issue with rotten wood that the workers who installed our siding just covered up…so we are very grateful. Because of their services we would highly recommend Omni Glass to everyone.  And the windows are outstanding too!   ~ Roxanne D. – Oshkosh, WI

I just called to compliment the man who installed my new shower door.  Jeff was very pleasant, he did an AWESOME job, everything is perfect, and he left the place neater than when he arrived!  Everything lines up, everything fits, nothing leaks! I am so happy with the job he did!   ~ Nancy, Oshkosh, WI

I just wanted to congratulate the great crew we had working at my home, they were fantastic.  I am very, very pleased with their knowledge and abilities, they were the most impressive group of people I have ever worked with. Mark was especially helpful, he was absolutely wonderful to work with. Thanks again!   ~ Rick, P

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