Can I split Plossl lens pairs?

[Lung]

I dismantled my Tal 25mm Plossl eyepiece to clean it as it was filthy,  but some demin water seems to have got inside the front lens pair. Will it dry out over time, or can I split the lens to dry it out?

[John]

It might be difficult to split them without damage - the 2 elements are cemented together and the cement is quite tough.

Best leave that pair to see if the moisture will evaporate naturally I think.

[Naughty Neal]

You could try placing the lens in a sealed container with some decassent sac's to se eif they can draw out the moisture.

[Don Pensack]

It is possible to dissolve the glue and re-cement the elements, but unless you want to do it for the experience, you'd have to value your time at zero to make it worthwhile.

You have a stain on the lens that will impact its usability, so you have three choices:

1) buy a new eyepiece

2) separate the lenses and clean them, then re-cement.

3) find a used version of the same eyepiece and snitch an element from it.

 

FWIW, the fact water got in is an indication it was improperly cemented in the first place.

[Lung]

Thanks all. I think it's worth trying some dessicant I reckon, or trying to draw it out via capillary action (which I tried yesterday but not for very long). It's also some way from the middle of the lens so I can probably live with it for the time being while I learn the astronomy ropes.

[Louis D]

I wonder if you could try an alcohol or acetone soak to see if it could coax the water out or clean up the stain.  The acetone might dissolve the cement, though.  Regardless, the cement clearly doesn't cover the entire surface of the two joined lenses.