There are many common methods for glass cleaning, which can be summarized as solvent cleaning, heating and radiation cleaning, ultrasonic cleaning, discharge cleaning, etc. among them, solvent cleaning and heating cleaning are the most common. Solvent cleaning is a common method, which uses water, dilute acid or alkali containing cleaning agent, anhydrous solvents such as ethanol, propylene, etc., or emulsion or solvent vapor. The type of solvent used depends on the nature of the contaminant. Solvent cleaning can be divided into scrubbing, immersion (including acid cleaning, alkali cleaning, etc.) and steam degreasing spray cleaning
Scrubbing glass
The simplest way to clean glass is to rub the surface with a absorbent cotton, which is immersed in a precipitated mixture of silica, alcohol or ammonia. There are indications that white marks can be left on these surfaces, so these parts must be carefully cleaned with purified water or ethanol after treatment. This method is most suitable for pre cleaning, which is the first step of cleaning procedure. It is almost a standard cleaning method to wipe the bottom of lens or mirror with lens paper full of solvent. When the fiber of lens paper rubs the surface, it uses solvent to extract and apply high liquid shear force to the attached particles. The final cleanliness is related to the solvent and the pollutants in the lens paper. Each lens paper is discarded after being used once to avoid re pollution. A high level of surface cleanliness can be achieved with this cleaning method.
Immersion glass
Soaking glass is another simple and commonly used cleaning method. The basic equipment used for soaking cleaning is an open container made of glass, plastic or stainless steel, which is filled with cleaning solution. The glass parts are clamped with forging or clamped with a special clamp, and then put into the cleaning solution. It can be stirred or not. After soaking for a short time, it is taken out of the container, Then dry the wet parts with uncontaminated cotton cloth, and inspect with dark field lighting equipment. If the cleanliness does not meet the requirements, soak again in the same liquid or other cleaning solution, and repeat the above process.
Pickling glass
The so-called pickling, is the use of various strengths of acid (from weak acid to strong acid) and its mixture (such as the mixture of Grignard acid and sulfuric acid) to clean the glass. In order to produce a clean glass surface, all other acids except hydrochloric acid must be heated to 60 ~ 85 ℃ for use, because silica is not easy to be dissolved by acids (except hydrochloric acid), and there is always fine silicon on the surface of aging glass. Higher temperature is conducive to the dissolution of silica. Practice has proved that a cooling dilution mixture containing 5% HF, 33% HNO3, 2% teepol cationic detergent and 60% H2O is an excellent general liquid for cleaning glass and silica.
It should be noted that pickling is not suitable for all glasses, especially for glasses with high content of barium oxide or lead oxide (such as some optical glasses). These substances can even be leached by weak acid to form a kind of thiopine silica surface.
Alkali washed glass
Alkaline glass cleaning is to use caustic soda solution (NaOH solution) to clean glass. NaOH solution has the ability of descaling and removing grease. Grease and lipid like materials can be saponified by alkali to form lipid anti acid salts. The reaction products of these aqueous solutions can be easily rinsed out of the clean surface. Generally, the cleaning process is limited to the contaminated layer, but the light use of the material itself is allowed. It ensures the success of the cleaning process. It must be noted that there is no strong genus effect and leaching effect, which will damage the surface quality, So it should be avoided. Chemical ionization resistant inorganic and organic glass can be found in glass product samples. Simple and composite immersion cleaning processes are mainly used for cleaning small parts.
Degreasing and cleaning glass with steam
Steam degreasing is mainly used to remove surface oil and broken glass. In the cleaning of glass, it is often used as the last step of various cleaning processes. The steam stripper is basically composed of an open vessel with a heating element at the bottom and a water-cooled serpentine around the top. The cleaning fluid can be isoendoethanol or an oxidized and chlorinated carbohydrate. The solvent evaporates to form a hot high-density gas. The cooling coil prevents the loss of steam, so the steam can be retained in the equipment. Hold the cold glass to be washed with special tools and immerse it in concentrated steam for 15 seconds to a few minutes. The pure cleaning liquid gas has high solubility for many substances. It forms a solution with pollutants on the cold glass and drips, and then is replaced by a purer condensing solvent. This process continues until the glass is overheated and no longer condenses. The larger the heat capacity of the glass is, the more time the steam continuously condenses to clean the soaked surface. The glass belt cleaned by this method has static electricity, This charge must be treated in ionized clean air to dissipate longer.
In order to prevent the attraction of dust particles in the atmosphere. Because of the power effect, the dust particles are strongly attached, and vapor degreasing is an excellent way to obtain high quality clean surfaces. The cleaning efficiency can be tested by measuring the friction coefficient. In addition, there are dark field test, contact angle and film adhesion measurement. These values are high, please clean the surface.
Cleaning glass with spray
Jet cleaning uses the shear force exerted by the moving fluid on the small particles to destroy the adhesion force between the particles and the surface. The particles are suspended in the flow fluid and taken away from the surface by the fluid. The liquid usually used for leaching cleaning can also be used for jet cleaning. At a constant jet speed, the thicker the cleaning solution is, the greater the kinetic energy is transferred to the adhered particles. The cleaning efficiency can be improved by increasing the pressure and the corresponding liquid flow velocity. The pressure used is about 350 kPa. In order to obtain the best results, a thin fan nozzle is used, and the distance between the nozzle and the surface should not exceed 100 times of the nozzle diameter. High pressure injection of organic liquid causes surface cooling problems, and then water vapor is not expected to form surface stains. The above situation can be avoided by replacing organic liquid with hydrogen or water jet without dirt. High pressure liquid injection is a very effective method to remove particles as small as 5pm. High pressure air or gas injection is also effective in some cases.
There is a certain procedure for cleaning glass with solvent. Because when cleaning glass with solvent, each method has its own applicable scope. In many cases, especially when the solvent itself is a pollutant, it is not applicable. Cleaning solution is usually incompatible with each other, so before using another cleaning solution, it must be completely removed from the surface. In the cleaning process, the order of cleaning solution must be chemically compatible and miscible, and there is no precipitation in each stage. Change from acidic solution to alkaline solution, during which it needs to be washed with pure water. In order to change from aqueous solution to organic solution, a miscible cosolvent (such as alcohol or special water removal liquid) is always needed for intermediate treatment. plus
Chemical corrosives and corrosive cleaning agents are only allowed to stay on the surface for a short time. The last step of the cleaning procedure must be done with great care. When wet treatment is used, the final flushing solution must be as pure as possible. Generally, it should be very easy to use. The choice of the best cleaning procedure requires experience. Finally, the most important thing is that the cleaned surface should not be left unprotected. Before the last step of coating treatment, it is strictly required to store and move properly.
Post time: May-31-2021