How To Clean A Reflector Telescope – A Guide For Beginners!!

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The thing with reflector based systems is that there lenses for the most part tend to be exposed. This means that they are a lot more susceptible to being covered in dust even when a dust cap is worn to minimise it.

In turn this of course means that they will need to cleaned as regularly as possible.

However, this isn’t an easy thing due to a number of factors.

These factors include the reflective mirrors generally being a lot more delicate than the glass lenses found within refractor telescopes and areas of compound systems therefore, they could suffer far more obvious permanent damages when cleaning them.

That’s why in this article I’ll aim to break down the process you’ll need to follow to minimise any problems, along with how you should go about cleaning your reflector telescope efficiently and effectively l

A brief explanation of the steps required for to cleaning the mirrors within your reflector telescope would go as follows :

  • Step 1: Remove the primary and secondary mirrors using screwdrivers, an allen key and pen
  • Step 2: fill up a bucket with lukewarm water using a couple drops of detergent and allow your mirror to sit in it for 5 minutes
  • Step 3: You’ll want to remove the previous water and refill the bucket again with lukewarm water and detergent to soak your high-grade cotton in. You’ll use these soaked cotton buds and through it’s weight alone gently brush across the surface of the mirror to clean it.
  • Step 4: after cleaning the mirror with the cotton bud you’ll firstly want to wash off all the soap on its surface using warm water and after the soap has been removed, use distilled water to further clean it up.
  • Step 5: the final step will require you to place your telescope mirror on a clean towel, propped up in a steep angle to allow for the distilled water to drain off it whilst using a paper towel to gently remove the droplets on the edges. After the mirrors are dried up you should be good to install it back into your telescope

Due to the complexity of cleaning the mirrors of a telescope, I would recommend you go to an expert to get it cleaned up if you’re not comfortable doing so  yourself but, if that’s not an option, I’ll break down the steps mentioned above in more detail down below

Why Do You Need To Clean A Reflector Telescope?

This is a pretty simple question to answer, in short if you don’t clean the lenses on your reflector system, the mirrors will get dirty and in turn this dirt will result in your overall image quality really nosediving.

Furthermore, if you do not clean it up as you should do on a fairly regular basis, the dust build up may even become a nuisance and may result in your mirrors getting scratched, which is definitely not something you’d want to happen.

Even with the use of a dust cap, smaller pieces foliage and other forms of dust along with the forming of dew will result in a reflector systems mirrors eventually getting dusty so, to counteract that you will more than likely want and even in some cases need to clean it off.

What Equiment Will You Need

Firstly before moving onto the cleaning side of things, allow me to list down the main equipment you’ll need when attempting to clean your telescope.

The equipment that’s required includes the following :

  • Clean towels : where you would place your mirrors after cleaning them
  • Detergent : used to clean the mirrors
  • Distilled water (if you can find it) : to wash the soap off the telescope mirrors at the end
  • Highgrade cotton wool : the high grade cotton is essential for safely removing and cleaning the dust from the mirrors
  • Screwdrivers, Allen keys and pen : these will be used to open up your telescope and take out the mirrors for cleaning as well as for putting your device back together
  • Lukewarm tapwater and a plastic bowl : it’s within this bowl, which will likely be in your sink, where you’ll clean the mirror.
  • Air compresser/blowing tool (optional) : these are most effective for minimising any type of mirror damage that may occur through manual removal of the dust

How Do You Clean Your Reflector Telescope?

The first thing you’ll need to do before attempting to clean the mirrors is of course to remove them from within the tube. This is where you’re screwdrivers, allen key and pens will come in handy.

Normally you’ll be required to unscrew a few screws at the backend rim of your system, remove the multiple mirror strips that attach the mirror to the cell (normally around 3 or so) before gently removing the mirrors

In fact before removing the mirror you’ll want to mark the vertical edge of the mirror and the cell to ensure that you can reassemble the primary mirror in the same position afterwards.

As for the secondary mirror, you’ll want to lay your telescope down horizontally and carefully hold the mirror whilst undoing the central screw holding it in place.

Of course every system will be slightly different when it comes to the removal process so I would recommend checking out a YouTube video on your specific reflective system to get a more visual understanding of how to take apart your mirrors.

Cleaning The Primary Mirror

After you’ve taken your primary mirror out and have all of the equipment mentioned above, you should be ready to get your primary mirror cleaned up.

Firstly, you’ll want to fill up a bucket with lukewarm water with a couple drops of soap/detergent placed in it and then place the primary mirror inside.

The primary should soak in the bucket for around 5 minutes. After the 5 minutes have passed you’ll want to rinse it with lukewarm water before moving on to the next step.

After this you’ll want to get rid of the used water and refill it again bucket mixed in with some more detergent, grab your high grade cotton, soak it in the mixed water and allow the cotton wool to clean the mirror using its own weight to gently remove the dirt from it’s surface.

Remember you don’t want to add any force when wiping, just allow the weight of the soaked cotton to drag across the surface.

Once you’ve wiped the mirror clean you’ll want to empty the bucket once again and place the mirror within the bucket and use as much water as you need to remove all the detergent on the mirrors surface before finally rinsing it with as much distilled water as is necessary.

Lastly, you’ll want to place the primary mirror on a clean towel whilst proping it up in a somewhat steep angle. This is so you can let the distilled water drain off the surface before carefully removing the droplets on the edges using either a paper towel or even a cotton bud.

After the mirror has dried up, you should be able to put it back into the base of your telescope following the marking you placed initially to accurately do so.

For a more visual look at the whole process, I’d suggest checking out the video below.

Cleaning The Secondary Mirror

You’ll want to take the secondary mirror, ideally at a similar time to when the primary mirror is taken out and more or less follow the same steps in the cleaning process.

So you’ll want to place the secondary mirror in a bucket of lukewarm water filled with a few droplets of detergent for about 5 minutes, clean it with a soap filled high-grade cotton bud very gently, wash off the mirror using warm water and distilled before propping it up at a steep angle on a clean towel to allow the distilled water to drain off.

Of course after it’s dried up you’ll want to place the mirror back into the front of your device.


Hopefully this article along with the video provided will help you out if you ever decide to clean a reflector telescopes mirror down the road.

The fact is that cleaning these systems are lot easier said than done so, I would always recommend you do so in a cautious manner or even ask an expert to do it for you . Then again even experts will make mistakes so learning the whole process isn’t a bad thing either.

All I can say is that if you do plan on cleaning your reflector telescope’s mirrors, make sure to be very very careful.

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