Originally Posted by gregoryzim
Tks - I will try it. If I'm making a new one - what is balsam sold as or where is it sold? Do they still use it in optics or is there some new chemical product in the 21st century?
Optical balsam does show up from time to time on eBay but is not cheap I guess because it has to be highly refined and is highly specialized. https://www.ebay.com/itm/Canada-Bals...frcectupt=true
There are some more modern alternatives I understand. This appears to be one such alternative but there is no real description of its uses but it seems to be the sort of thing used. https://www.ebay.com/itm/NEW-Astro-O...frcectupt=true
You can Google this subject and I am pretty sure you will find how the process is carried out - I seem to recall seeing such posts at some time. Use this search phrase "alternatives to balsam for optics" and "optical lens glue"
In the event that you are ever working on an existing balsamed element an alternative if yours is not too far gone is to gently heat the lens group having first removed it from the lens barrel, cleaned it etc then when the balsam melts under heat to push the elements together. And I believe the google search will find posts where people have discussed how they have done this.