Yellowing Super Tak? Unconventional fix.

http://www.hermes.net.au/bayling/repair.html

Don't try this at home

Just think of the radioactive dust polluting the atmosphere!

Kim

Very effective method i would say
Oddly enough i was just browsing Kim's Website and reading another method of fixing yellowing in lenses and it looked nothing like the one you have produced

There is a link to the "hammer" method in the article on yellowing.

Kim

Oh i must have missed it

I remember seeing a post somewhere on a different forum where a guy had some pics of a yellowed lens (it was very noticeable) and he was asking how to remove it. Nobody could help so he took to it with (i think either turps or metho) and it cleaned up a treat. I think he just erased the entire SMC though

It would not have been the normal yellowing then. The yellow is actually in the glass. At the time Pentax used thoriated glass for one of the elements. It is very mildy radioactive in the same way luminous watches were. As the thorium decays, it causes the glass itself to yellow. It is easily reversed by exposure to UV light.

The "cure" is here together with some links to the background. http://www.pentax-manuals.com/repairs/yellow.htm

Kim