How do you clean refractor diagonal?

[KenLM (Ken)]

I have successfully cleaned the main and secondary mirror in a reflector several times with never a problem. Now I have one of these refractor telescopes with a 2" diagonal at one end. A little dusty I have dealt with a blower no problems. Now I have some water residue from dew but I dare not touch the surface.

What is the the accepted safe way to clean a refractor diagonal? I am thinking of gentlely flushing with filtered/distilled water but a little worried about what that might do to the insides of the diagonal housing! Anyone with some tips?

Thanks... Ken

[DavidU (Dave)]

Ken, I just undo the screws on the back plate and remove the mirror and wash it the same way I do the Newtonian mirror.Put it all back together......quite easy.

[KenLM (Ken)]

David, Job done - almost!
Added a dash of Iso-alcohol and bubble bath into the mix. Followed by a rinse with filtered water. All very shiney now. Thanks for your tip.

Ooops... Mirror fell out of the holder, soft towel on bottom of dish caught it all, pays to be cautious. Waiting for eveything to dry before deciding what to do next. There was a soft pad underneath which doesn't appear to have been a sticky surface. Looks like it was just sitting there the whole time. This is a high desinty black foam pad that will take a long time to dry.

Anyone have a hint for this?

[KenLM (Ken)]

There were no further replies so I took a leaf out of Richard Berry's book: Build your ow telescope. Added three very small dabs of silicone around the edge to hold the mirror in. If I ever want/need to take the mirror out I can slice through the silicone with a hobby knife.

Easy peasy and very shiny. Job all done now.

[dannat (Daniel)]

the foam was probably there to prevent rattling against the back surface,,when you glued it was it lined up - was there any lateral movement

[KenLM (Ken)]

You got that exactly right. The foam went back in and it's all snug. The drops of silicone are there to make sure it doesn't go anywhere.