Glass Lid, Normal Dome Tempered Glass Lid for Cookware

Test for quality control:
1. FLATNESS CHECK
Place the glass lid on a completely smooth table , and put a piece of 1mm thickness iron plate beside the ring the glass lid, then moving the iron gauge along with the circumference of the lid, the glass lid passes the test if the iron plate does not push in

2. HTERMAL SHOCK
Put the glass lid into oven temperature to 200°C, and constant temperature for 30 minutes, remove it immediately into 20°C water , glass no broken or crack

3. IMPACT TEST
Place a lid, domed size up, on a hard surface,
Dropping a 225 grams steel ball from a height of 1.5meter,
No fracture no shatter, to pass
Note : Don't drop the ball near or onto a vent hole /rivet hole 

4.SCRATCH TEST (PRESSURE TEST)
Use 120-grit (abrasive paper ) sandpaper to scratch two side and three directions 15 times, then put into room temperature water for 15 minutes, it pass if no breakage and no crack.

5. POLOLARISCOPE CHECK
To test the balance of compressive stress and tensile stress depends on the color what you see.

6. FRAGMENTATION CHECK
Apply tape (adhesive film)on the convex (front) surface of the lid, domed side upward, break it with a hammer broken 5X5cm measuring range , number of particles (fragments) counted should be at least 40,
The purpose of this test is to determine whether the glass has been adequately toughened.