In the actual production, there are many reasons for the bubbles inthe float glass.

Lassifying  the bubbles according to its source can help find out the reasons and

 appropriate solutions.Generally speaking, bubbles in the float glass are mainly produced

during the melting process and then molding in the tin bath. The first type of bubbles is

refined bubbles residual in the glass after the primary melting and refining. The second

is caused by the  re-deposition of dissolved gases. The third is bubbles entrained gas,

 liquid or solid foreign objects. They are air bubbles, work bubbles, iron bubble and

pollution bubbles caused the impurities and  refractory materials. Distinguishing the type

of bubbles can help speculate in which area the defects are produced.According to the

 reasons of bubbles, bubbles can be  divided into primary bubbles, secondary bubbles,

 external air bubbles, bubbles caused by refractory materials and impurities, etc..

1)Primary bubbles

After refining, some air or gases is not completely removed, or re-deposited from glass

liquid. Those air and gases remain in the glass and produce the primary bubbles. 

As we all know, when the formulation is the same, the refining of  glass liquid can be

affected by different reasons: whether the ingredients in the raw materials that can

produce gases can intensively decompose and release gases, whether the tiny unreleased

bubbles can be dissolved in the glass and disappear., whether the dissolved gases in the

melt can be deposited from the  melt quickly, whether the deep flow at the beginning of

the refining  flow can proceed smoothly upward and release bubbles, the

refining  temperature, time,   external pressure, etc..

2)Secondary bubbles

The refined glass liquid should be in equilibrium state with gases  dissolved in it. When

The conditions are changed, bubbles or gray bubbles will appear again in the glass

 liquid. Those are the  secondary bubbles. Under normal production conditions, the

external factors will not  cause the reheating of glass liquid and the sudden change of the

atmosphere and result in the re-deposition of  gases in the. Only the reflux of the melting

zone and cooling zone can cause the reheating  of glass liquid or malfunction causes the

sudden change of the atmosphere which can cause the re-deposition of gases. 

3)External air bubbles

Those bubbles are caused by the poor working condition of the  blender such as bad

bubbling and entangling when molding. If  handled properly, those bubbles are easy to

exclude. 

4)Bubbles caused by refractory materials

The impurities or pores in the refractory materials may cause bubbles when in contact

With  the glass liquid. The pores, iron or carbon can react with the glass and cause

bubbles. The gases exhausted from the pores in the refractory of the cooling zone

and  molding zone or the reduction of iron silicate may produce a large amount of tiny

bubbles. It is at greatest risk when the bubbles near  the molding area such as the launder

bricks. 

5)Bubbles caused by impurities

Some solid or liquid inclusions can directly enter the melt such as the duct or condensate.

The substances in the refractory materials or  metals enter the melt due to the corrosion.

both can cause bubbles.In the actual production, there are many reasons for the bubbles

in the float glass.   Classifying the bubbles according to its source can help find out the

reasons and appropriate solutions.