a while ago I got ready-to-use cleaned fossile radiolaria from Barbados. I began to think about what mountant I should use to make slides from this material. A high refractive Index is not necessary for radiolaria. Some radiolaria are quite big so this won't be a very thin preparation. A mountant that would shrink a lot might crush the big radiolaria. So I came to the idea to use an UV hardening adhesive. Here I had 3 types in the drawer: Stuff to glue false finger nails on, stuff to smear onto the nails and stuff called LOCA (liquid optica clear adhesive) for glueing glas screens onto smartphone displays. I chose to use LOCA. I bought the cheapest that was available on ebay. I have no experience what differences there are. LOCA is mostly sold without an explicit maker information so there might be surprises.
What did I do?
- round cover slips cleaned with ethanol and moved through the flame of an alcohol flame (for optimal spreading on the cover slip)
- drop of radiolaria in water onto the cover slip (difficult to get the right density)
- drying at 90 °C
- 1 drop of LOCA onto the cover slip (seem to penetrate very well)
- holding slide over cover slip, capillary forces attach it upwards to the slide
- applying and releasing vacuum 5x to remove bubbles, not strictly necessary (cover slip down)
- Into UV-lamp (cover slip down) for a couple of minutes (I use a pink finger-nail thing, always easy to find
)- LOCA becomes like cured silicone, elastic but not fluid
- apply paint ring (I don't know how important this is)
=> All radiolaria right below the cover slip, good contrast in the slide
=> 2 month storage showed not sinking down of radiolaria
I keept the cover slip down through the whole process and was rewarded with a nice even preparation. There are still some bubbles in the slide, so there is room for improvement. The big advantage of LOCA is that it doesn't shrink wihile curing, and that it is really fast. I can't say much about it's other properties so I don't know whether it would be suitable for the mounting e.g. of stained botanical sections.
Curing with sunlight is probably also possible. I can't test it because we don't have any at the moment, rain, rain, more rain...
The used LOCA was something like this: https://www.ebay.de/itm/UV-Loca-TP-2500 ... Sw3WxZ6gzX
It would be nice if you try it out for your applications and report your experiences here.
The image is not stacked, 10x objective, bright field
Bob
