[Nhcoll-l] [EXTERNAL] light damage to microscope slides?

[Simon Moore]

C. Balsam, despite being an archival mountant is nonetheless vulnerable to gradual oxidation. If it show any discolouration at the edges of the coverslip, this is usually what has happened and that can affect the colour of historical dyes.

With all good wishes, Simon 

Simon Moore MIScT, RSci, FLS, ACR
Conservator of Natural Sciences and Cutlery Historian.

www.natural-history-conservation.com



> On 27 Apr 2026, at 19:12, Woodward, Jon <jwoodward at oeb.harvard.edu> wrote:
> 
> Thanks all -- 
> 
> Kevin, the mountant is Canada balsam. The proposed term of the exhibition is (IIRC) between six months and a year. 
> 
> Regular pictures with a settings template is a good idea. 
> 
> --Jon
> 
> 
> 
> From: Kevin Kocot <kmkocot at ua.edu>
> Sent: Monday, April 27, 2026 12:55 PM
> To: Woodward, Jon <jwoodward at oeb.harvard.edu>; Nhcoll-l at mailman.yale.edu <Nhcoll-l at mailman.yale.edu>
> Subject: Re: [EXTERNAL] [Nhcoll-l] light damage to microscope slides?
>  Hi Jon,
> 
> My sense is that Orange G is not particularly sensitive to photo bleaching but the cochineal might be. What are the sections mounted in? How long will the exhibit be up? 
> 
> Presumably the LED photo table produces little to no UV light and I think the motion activated light is a great idea. I think you don't have much to worry about for a short-term exhibit, but I'm not sure if anyone's going to be able to give you a confident answer. 
> 
> If you say yes, you might ask the borrower to regularly take pictures (even a quick macro photo of the slides in situ with one's phone using a camera app that forces all the same settings) and compare them over time to watch for signs of fading.
> 
> Best,
> Kevin 
> 
> 
> 
> 
> 
> 
> From: Nhcoll-l <nhcoll-l-bounces at mailman.yale.edu> on behalf of Woodward, Jon <jwoodward at oeb.harvard.edu>
> Sent: Monday, April 27, 2026 9:26:04 AM
> To: Nhcoll-l at mailman.yale.edu <Nhcoll-l at mailman.yale.edu>
> Subject: [EXTERNAL] [Nhcoll-l] light damage to microscope slides?
> 
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> Hi all, 
> 
> We've gotten an exhibition loan request for some microscope slides which preserve the histological serial sections of a hagfish embryo. The slide prep was done (very nicely) in 1926. The stain was recorded as "Alum cochineal and Orange G." The sections are a little faint, and we're worried that putting them on display (on an LED light table) might result in further fading or other damage. The borrower proposes to put the light on a motion sensor, so the slides would only be lit when a visitor was nearby, rather than 24/7, which seems sensible. I would welcome anyone's thoughts about possible risks and mitigations. 
> 
> Thanks,
> Jon
> 
> 
> -------
> Jon Woodward
> Digitization Manager, Collections Operations
> Harvard Museum of Comparative Zoology
> 26 Oxford St.
> Cambridge, MA 02138
> 617-495-8205
> 
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