Corrosion

[Pluto1948]

Hi Guys

Can anyone give me some advice on how to solve a problem of corrosion affecting my LX200 GPS 10" scope I need to try and rectify it so it doesn't c get any worse, once this is done I then need to have it painted so it looks like new.

[Peter Drew]

The components are aluminium alloy castings and as such are relatively porous. This always eventually gets permeated with damp and corrosion takes place. Cleaned up the castings will be rather pitted and will require filling and rubbing down before repainting. A good etch primer before painting will be essential to prolong its new coat. 

[Pluto1948]

Hi Peter 

Thanks for the info, I have my Dremmel at the ready, and I hope I have found a company called Corrosion X that sell preventative agents for alloy, my other problem is the painting once cleaned and polished it will have to be powder coated for the finish unless you can offer an alternative.

[trazor]

Hi Peter 

Thanks for the info, I have my Dremmel at the ready, and I hope I have found a company called Corrosion X that sell preventative agents for alloy, my other problem is the painting once cleaned and polished it will have to be powder coated for the finish unless you can offer an alternative.

My suggestion is to keep your Dremmel  and preventative agents well away from your scope.

Strip down, and take the parts to a local powder coaters.

They will have all the knowledge and equipment to provide a first class finish.

[perfrej]

I see aluminium and stainless steel screws... That combo eats the aluminium as it is more anodic. Stainless steel has about -0.60V with respect to gold, aluminium has -0.95V. The difference of about 0.35V is considered above the safe level for corrosion (0.25V) in a normal environment. In more humidity controlled environments, a 0.5V difference can be acceptable, while more salt and humid environments will need a smaller difference to be safe.

Sorry to say, this factor is not always considered by telescope and mount manufacturers, and many parts of our equipment are essentially batteries that last until the aluminium is completely converted to aluminium oxide

You should redo the ring properly (powder) as suggested above and consider using high quality nylon screws if they can take the load.

All the best,

Per