Page 7 of 7 FirstFirst ... 567
Results 61 to 66 of 66

Thread: How I did it: new balsam for a sick RR

  1. #61

    Join Date
    Jan 2015
    Location
    Arlington, Texas
    Posts
    58

    Re: How I did it: new balsam for a sick RR

    Click image for larger version. 

Name:	P1140277.jpg 
Views:	29 
Size:	50.2 KB 
ID:	163793

    After about 10 minutes of warming, (ok, it's hot now) the original 125+ year old balsam is melting and the 2 pieces came apart.

  2. #62

    Join Date
    Jan 2015
    Location
    Arlington, Texas
    Posts
    58

    Re: How I did it: new balsam for a sick RR

    Click image for larger version. 

Name:	P1140289.jpg 
Views:	26 
Size:	32.3 KB 
ID:	163794

    After cooling in the pan to room temperature, I removed the lenses and put them on a paper towel to dry.

    Next step is to wipe the lenses clean with alcohol.

    More to follow.

  3. #63

    Join Date
    Jan 2015
    Location
    Arlington, Texas
    Posts
    58

    Re: How I did it: new balsam for a sick RR

    Click image for larger version. 

Name:	P1140302.jpg 
Views:	23 
Size:	30.1 KB 
ID:	163894

    After cleaning both lenses with alcohol, I placed a small piece of blue tape on each of the "facing out" sides of the lens. Then cleaned again with a mild window cleaner to make sure all the old balsam was gone.

  4. #64

    Join Date
    Jan 2015
    Location
    Arlington, Texas
    Posts
    58

    Re: How I did it: new balsam for a sick RR

    Click image for larger version. 

Name:	P1140307.jpg 
Views:	32 
Size:	50.3 KB 
ID:	163895

    Pressing both lens elements together caused the balsam to spread out to the edges of the lens. After double checking the alignment, I used a simple Craftsman brand pressure clamp to hold the lenses together as the balsam dries.

  5. #65

    Join Date
    Jan 2015
    Location
    Arlington, Texas
    Posts
    58

    Re: How I did it: new balsam for a sick RR

    More to follow when dry.

    Oh, and a huge thank you to Steven for his inspiration.

  6. #66

    Join Date
    Jan 2009
    Location
    Denmark
    Posts
    5,322

    Re: How I did it: new balsam for a sick RR

    Based on old and recent experience, I have found that the occasional devitrification which occurs seems to be associated with:-

    Crown glass used in both Petzval achromats and Rapid Rectilinear (Aplanat) doublets. This is a glass which was used extensively from the start of Photography.

    It is a phenomenum which starts at the surface and can spread into the body of the lens. Both degrees of attack mean a scrap lens. The flint glass is always OK,

    For sometime I thought that use of aqueous solutions used in the separation of cemented lenses might be the cause (microscopic defusion of water molecules into the glass skin) but this is not so. All glass failures have occured during gentle warming. I used to recommend heating as a way of speeding up the slow solvent dissolution of hardened balsam. I now think that the only safe way to harden the new balsam is warming to just over room temperatures in one process. I have examples of repeated warming to just under 100 degree which went OK the first few times, then, suddenly it happened in just a few minutes! Repeated temperature stress is a killer for crown glass.

Similar Threads

  1. Balsam Breakdown on ML Petzval
    By Pete Watkins in forum Lenses & Lens Accessories
    Replies: 9
    Last Post: 30-Dec-2009, 02:52
  2. replacement of Canada Balsam?
    By jack_hui in forum Lenses & Lens Accessories
    Replies: 9
    Last Post: 29-Nov-2009, 15:48
  3. Aero Ektar: balsam fault?
    By kilimanjaro1996 in forum Lenses & Lens Accessories
    Replies: 5
    Last Post: 27-Oct-2009, 20:23
  4. Canada Balsam
    By lungovw in forum Lenses & Lens Accessories
    Replies: 9
    Last Post: 18-Jun-2008, 18:43
  5. sick and tired-please help
    By P. Robertson in forum Darkroom: Film, Processing & Printing
    Replies: 11
    Last Post: 17-Nov-2005, 22:48

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •