[photo-3d] Film slippage in RBT mounts

[Paul Talbot <list_post@xxxxxxxxx>]

On the usviews list, Jim Harp wrote regarding a slide
received by postal mail:
 
> Strangely enough the RBT mounted slide arrived with the left
> chip slid towards the center so much that part of the left
> aperture was open.   Apparently the chip had slid during
> shipping.  It was very easy to slide the chip back into place,
> and I got to set the window to my liking.  Has anyone seen
> this happen before?   

Yes, the same thing has happened to me, both in receipt of a
usviews slide and in a slide submitted to a Detroit club
competition.  This definitely makes me nervous about mailing
RBT-mounted slides to PSA salons!

Variability in the snugness of fit of RBT pin bars in the
mount channels has been mentioned on photo-3d before.  What
happened in these three cases seems to be an extreme case of
this looseness problem.  (In the two cases I have seen, light
finger pressure on the film chips, with the mount still snapped
shut, was sufficient to slide the pin bar inside the channel.)
I have no data on how common it might be for the problem to be
this severe.

I think I recently read someone mention always taping down the
RBT pin bars.  While that adds an extra step, it seems like it
might be a wise precaution when mailing slides mounted in RBT
mounts.

Paul Talbot