Welcome to the Group Grant!

I haven't been collecting as long as you have, but did start a few years
ago. It started when I went to replace an old slide rule I carry in
the car. Surprise! You can't just buy them at the corner store anymore.
Well, the rest is history.

As for your question on the yellowing. I have also heard the same as
you about exposure to sunlight. You don't want to do is for a long
period of time like days or something. What I have heard is to do it
a couple hours at a time. I know with a regular slide rule, they do like
to breath and the light does seem to cut back on the yellowing. I'd
give it a try for short periods. I admit, I am not an expert on this though.
You are a lucky one...at least you have a 4012. I have been looking
to get one someday, as well as a Fuller. I'd think eBay is probably
the best game in town, but they are pretty pricy. Good luck.

Regards,
Miles Schcumacher

..deletia...

>
>
> Two questions for members, if I may. First, I would like to brighten
> the yellowed scales of an old K&E Thacher 4012 but have been afraid
> to touch it for fear of making things worse. Someone suggested
> exposure to sunlight but that seems insane to me. Any suggestions?
> Also, I am looking for an original instruction book for the Thacher
> as well as for a Stanley Fuller Model II (the manual usually provided
> instructions for all three models). Does anyone know where I might
> locate either of these beasts? Thanks for a interesting forum for
> those of us who long for the feel of mahogany and celluloid.
> Grant Hutchinson