What is the etch rate for a pH 14 solution on silica glass at room temperature?

In summary, the etch rate for a solution with a pH of 14 on silica glass at room temperature will likely be very low, potentially on the scale of nm/month. However, it could also be higher if the solution contains strong bases like AlOH. If given the options of nm/hr, microns/hr, or mm/hr, the most likely option would be microns/hr based on visible etching observed at that concentration. However, this rate is still insufficient to completely dissolve glass beakers with a thickness of 1-2 mm.
  • #1
Claude Bile
Science Advisor
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Greetings,

Just a quick question.

I would like to know what order of magnitude the etch rate will be for a solution with a pH of 14 on silica glass (flat surface at room temp) - are we talking nm/hr? microns/hr? mm/hr?

Thanks,

Claude.
 
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  • #2
It's going to depend on what is in the solution.

Lots of strong bases (AlOH is one) are stored in silica glass. So at room temp, I'll ballpark that the rate is going to be very low.Perhaps nm/month?

You could etch glass with HF...
 
  • #3
If those were my three choices, I would say it is microns/hr. Visible etching is observed during that time at that concentration so the scale must be larger than a wavelength of light (500 to 900 nm) but the rate is insufficient to completely dissolve the bottom out of glass beakers (thickness of 1-2 mm) containing pH 14 liquid.
 
  • #4
Thanks for the responses.

Claude.
 

1. What is the purpose of using alkalis for etching glass?

Alkalis, such as sodium hydroxide and potassium hydroxide, are commonly used in etching glass because they are strong bases that can chemically react with the glass surface. This reaction creates a frosted or matte appearance on the glass, making it ideal for decorative or privacy purposes.

2. Is etching glass with alkalis safe?

Etching glass using alkalis can be hazardous if proper safety precautions are not taken. These chemicals are corrosive and can cause skin and eye irritation. It is important to wear protective gear, such as gloves and goggles, when working with alkalis. It is also recommended to work in a well-ventilated area to avoid inhaling any fumes.

3. Can any type of glass be etched using alkalis?

While most types of glass can be etched using alkalis, some glass may not react as well or produce the desired effect. For example, tempered or safety glass is more resistant to chemical reactions and may be more difficult to etch. It is best to test a small area of the glass first before attempting to etch the entire surface.

4. How long does it take to etch glass using alkalis?

The time it takes to etch glass using alkalis can vary depending on the strength of the solution and the desired level of etching. Generally, it can take anywhere from 5 minutes to an hour for the chemical reaction to occur. It is important to closely monitor the glass during the etching process to achieve the desired result.

5. Can the etched design on glass be removed?

Once glass has been etched using alkalis, the design is permanently etched into the surface and cannot be removed. However, the level of opacity can be adjusted by using a weaker or stronger solution. It is also possible to sand or polish the surface of the glass to remove some of the etching, but this may affect the overall appearance of the glass.

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