Re: Slide Mounting

[P3D emdesher <emdesher@xxxxxxxxxxxxxxxxxxxx>]

On Fri, 5 Sep 1997, P3D Karen Obusek wrote:

> Hi folks. I appreciate the help concerning slide mounting but one
> question remains unanswered. Can I safely project a non-protected slide
> for a few minutes to determine if I want to glass mount? Can this be
> done with any type of mount? It would be difficult at best to drop these
> in EMDE's just to preview! The efforts to jam them into glass and remove
> them again is not feasable. How long can I leave a slide in a projector
> before I run the risk of damage? (without glass)  Thanks
> MARK DOTTLE
> 
> 
It would be difficult to say, as physical damage may depend on what type of 
slide carrier you are using.  There are really only two reasons to glass 
mount a slide: first is to give physical protection to the film (to avoid 
scratches, fingerprints etc.) and second, to prevent the heat from the 
projection lamp from "popping" it or causing a curvature to the film.  This 
causes the slide to be out of sharp focus and necessitates a focus 
readjustment.  Contrary to what some believe, enclosing film in a glass 
mounted slide does not prevent heat damage; that's what the heat absorbing 
glass in the projector's light path is for.  So, the length of time any slide 
can be left projected is more a function of how good the projector's cooling 
system is (ignoring the question of film fading due to light exposure), rather 
than the type of mount used.  Dennis Sherwood   emdesher@xxxxxxxxxxxx 


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