How to Clean a Telescope Mirror Using Alcohol

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Cleaning Telescope Mirror Alcohol

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After proper dusting, your telescope mirror surface, spray the solvent (alcohol). You can either opt to use a tissue or cotton to wipe off the solvent. However, for proper cleaning, lay the tissue across the mirror and pour a little solvent on it. It will stick to the mirror through surface tension, and you will gently drag the tissue sideways off the mirror. 

Telescope mirror cleaning should only be done when necessary. Therefore, frequent or aggressive cleaning can prematurely age or damage the special coating on the lens or mirrors.

That might lead to permanently degrading the performance of your telescope mirror. However, when your optics are truly dirty, that’s when you need to clean them. One of the best tactics is advanced cleaning.

Where you tend only as much as you need your mirror clean, begin with the gentlest cleaning and progress to thorough cleaning. 

Simple Steps of Cleaning Telescope Mirror

In the telescope mirror cleaning process, it is crucial to blow off dust using compressed air. Additionally, ensure that the mirror remains in the telescope tube with the tube ends facing downwards. Maintain at least a 1-foot distance away from the mirror when blowing off the dust.

After blowing, ensure that the tube faces downwards for about 15 minutes.  

The benefit of doing that is to ensure dust in the gadget gets out of the tube. You also get to avoid regular mirror cleaning.

1. Separate the mirror from the Telescope

You can separate the mirror from your Telescope by undoing the screws attaching the primary mirror cell to the end of the tube. Then gently pull out the cell with the mirror and unscrew the holding clips to get the mirror inside it.

Ensure to avoid touching the shiny surface.

You will also need to remove holders of the minor secondary mirror present at the front end of the tube to get the secondary mirror. The grit removing process is essential and should be performed correctly. 

2. Use Compressed air or gas to blow off loose dust.

The main benefit of blowing off loose particles is avoiding your lens or mirror from scratches in all successive steps. However, the use of canned gases requires precautionary measures since they contain bitterants and other compounds prone to leaving deposits. 

Always vent out a jet of gas away from the telescope mirror, then shake the can of compressed gas. Keep the can in an upright position while using it to move slowly or instead move the mirror.

Filter the compressed air or jet it away from the telescope mirror to blow off dust in the line. 

3. Use Cleaning solvent (Alcohol) to clean off remaining smudges or dirt gently.

Alcohol is the recommended solvent in lifting off any remaining dirt. The use of alcohol is most preferred for its high percentage of evaporation.

It also has more chances of dissolving optical cement, lacquers, and non-metallic compounds on mechanical parts if it accidentally penetrates through the wrong parts of a telescope. 

You can directly use pure alcohol in cleaning or add one or two drops of clear liquid dish-type soap per quart. That helps in lifting off dirt and finger oils from your lens.

Remember, too much soap is likely to leave a visible residue on your optics.

4. Use the solvent to wet plain tissue or cotton balls. 

When doing the procedure, ensure that you only use a little solvent to avoid excess fluid from running off to other surfaces. It would be best if you also considered the surface area of the optics you are to clean. 

Smaller optics like lenses, you only need cotton swabs and wipe with little or no pressure. It would be best to use straight strokes across the lens surface as you rotate the swap to lift dirt off the lens.

You can repeat the process to remove any remaining dirt or oil.

For the more enormous or primary mirror, consider using a tissue or cotton ball by wetting it and gently dragging it across the surface in straight strokes. Always ensure that you are pulling it with the lowest force possible.

That will provide the slightest chance of scratching from any remaining dust particles. 

If you are to repeat the procedure, ensure that you do it with new balls/tissues. Any force needed when dragging must be as little as you can.

Only enough to remove the deposit without damaging the mirror surface.

Tips to Keep Your Telescope Mirror Clean

  • Always avoid touching the mirror. Your skin contains oil that can probably corrode the surface coating of the telescope mirror. If you touch, wipe off with a cleaning solvent as soon as you can. Remember, only the dirt or dust that gets inside the Telescope requires advanced cleaning. 
  • Ensure that you keep the mirror/ lens cap on when the Telescope is not in use. If you might have misplaced it, make your own. All you need is a cover that holds and covers the mirror securely. 
  • Keep your Telescope pointing at the ground after you are done using it. By doing that, you prevent any dust from settling down on the mirror. 
  • Always consider using soft cotton or clothing to clean off dust from your mirror. Solid or fibrous materials can scratch the surface of the mirror. The scratching can significantly degrade your mirror, and it is vital to be keen when selecting wiping materials. 
  • Consider covering your Telescope with plastic when it is not in use. It is the best method of minimizing dust from accumulating on your device. 
  • Avoid storing the Telescope from direct sunlight. Always ensure it is in a position. 
  • Remember to plug the hole present on your focuser with a plastic 35mm canister after using your Telescope. 
  • Regulate the pressure of the compressed air when blowing off dust on the mirror. 

Final Thoughts

Telescope mirror cleaning is a simple procedure that any astronomer can do. You can also prevent dust accumulation by capping both ends and ensuring your device is well stored.

Additionally, it would be best to handle your telescope mirror with great care when cleaning to avoid scratches. The unscrewing and screwing when removing and returning the mirror should be professional to prevent breaking or loose holding of your mirror to the tube.


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