Best Practices Drymounts

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linuxusr
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Best Practices Drymounts

#1 Post by linuxusr » Sat Apr 24, 2021 3:58 am

I use mostly wetmounts and if I use drymounts, they are pre-purchased and fixed. Like a lot of people, I'm fascinated by diatoms but there's a lot to be said for found objects that you find in your environment, such as a salt crystal or a fly's wing.

So let me start with some problems and questions from a recent miscroscopy session: subject: a fly's wing.

In a wet mount, surface tension is broken with the cover slip, and there is no issue with the slip adhering to the slide. In the case of the fly wing, which I decided to leave attached to the body, I could only compress this hard object so much, and I kept dropping cover slips; they were sliding off my specimen left and right.

Is there some some substance I could use on the four corners of my slip to cause it to adhere? Or just not use a coverslip and find a way to adhere the specimen? I'm wonder if in a drymount that's not going to be fixed whether that coverslip is necessary at all. Avoiding contact with an objective lens would be a plus; however, objective lenses are below the metal surface of the objective that would actually touch a specimen or coverslip if you came up too short on your working distance.

Your best practices and hints will be appreciated.

FYI, I did get a great wing view. At 10x, the structure is made of straight lines and ellipses, squeezed at one end and open at edge. At 40x, I estimated about 10^3 hairs, each a bent cone. It was surprising to find the wing studded with hairs. 10x did not resolve them at all. The legs also have clusters of hair tufts. Any housefly wing observations?
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MicroBob
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Re: Best Practices Drymounts

#2 Post by MicroBob » Sat Apr 24, 2021 7:39 am

Hi,
I have little experience with dry mounts but my head is full of good ideas. :roll:
Genereally I like to make permanent mounts to be able to come back to them with different techniques etc. For a good slide the cover slip is necessary unless your objectives are not meant for use with one (e.g. on a metallurcical microscope). To mount the slide you have several options:

- place object on slide, fix cover slip with adhesive tape
- fix object to slide, add distancer of some kind, cover slip on distancer
- fix object to the cover slip, support cover slip over slide

To fix the objects you can use:
- thin layer of shellac (5% concentration coming from saturated solution), let dry, fix object by warming to 90°C
- sugar based diatom adhesives , breathe on to activate
- any kind of glue

For spacers you can use:
- wax bits on the corners of the cover slip
- washers
- gasket rings
- paper reinforcing rings
- DIN 988 shin washers

In the end you might have to cover the edges with paint to seal the slide.

Bob

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Re: Best Practices Drymounts

#3 Post by mrsonchus » Sat Apr 24, 2021 8:34 am

Hi, you may have a go at cutting some spacers from coverslips - see this post with example. It works very well indeed. To stick a dried specimen to the slide simply place onto a tiny amount of the resinous mountant used. The correct height of spacer is easily built-up from sveral layers of coverslip-pieces. It's far easier to cut a coverslip into a nice straight-edged rectangle than it looks!
John B

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Re: Best Practices Drymounts

#4 Post by linuxusr » Sun Apr 25, 2021 12:28 am

@MicroBob
@mrsonchus

This is exactly the information and hints I need and have been looking for. I'm calling it a day. I'll get back to you tomorrow. Just wanted to thank you in advance.
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Re: Best Practices Drymounts

#5 Post by mrsonchus » Sun Apr 25, 2021 8:57 am

linuxusr wrote:
Sun Apr 25, 2021 12:28 am
@MicroBob
@mrsonchus

This is exactly the information and hints I need and have been looking for. I'm calling it a day. I'll get back to you tomorrow. Just wanted to thank you in advance.
Most welcome. One other hint, when applying the dremel-bit or other suitable hard point to the glass for scoring the cut/snap - don't overthink the angle or face of the scoring piece to the glass - it's far easier than it looks. No great pressure is needed and a clearly visible scored line isn't a must either. If the score is there the glass will snap easily - so easily in fact than more often than not I simply pull-apart the pieces either side of the score without the need to 'snap' as with conventional e.g. window-pane glass cutting. Don't bother trying to snap it laid on a surface either as in tile-cutting etc, it doesn't work as the very thin glass is simply too flexible,

The main points for the scoring 'bit' are hardness (e.g. as in being able to mark glass) and the sharpish-point with which to score. The dremel bits I use aren't used 'as dremel bits' as it were, but as such a sharp and hard pointy-thing as needed. You can feel quite easily when the scoring bit has the right 'bite' to score the glass well.

I found this method to be really very easy and able to ensure amongst other factors that the finally-mounted coverslip will be parallel to the slide's surface as the coverslip thicknesses are easily reliable enough to be used for the thicker mounts as either single or indeed built-up layers of support....
Hmm, a few other hints then!
John B

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Re: Best Practices Drymounts

#6 Post by MicroBob » Sun Apr 25, 2021 10:02 am

For labeling slides and cutting cover slips I have a pen that was sold as diamond tipped, might be carbide. It wasn't expensive but works well as long as used only for this fine work.

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Re: Best Practices Drymounts

#7 Post by mrsonchus » Sun Apr 25, 2021 10:26 am

MicroBob wrote:
Sun Apr 25, 2021 10:02 am
For labeling slides and cutting cover slips I have a pen that was sold as diamond tipped, might be carbide. It wasn't expensive but works well as long as used only for this fine work.
That sounds just the job! I think I'll have a look for such a pen, it would be pretty handy and easier than getting out the dremel bits.
John B

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Re: Best Practices Drymounts

#8 Post by MicroBob » Sun Apr 25, 2021 11:53 am

Hi John,
this is the one I bought and I like it: https://de.aliexpress.com/item/32906393 ... 4c4dSHExGM
It actually has a dark tip insert so it's not plain steel, but I can't determine whether it's diamond or carbide. It works! :D

Bob

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Re: Best Practices Drymounts

#9 Post by 75RR » Mon Apr 26, 2021 1:04 pm

MicroBob wrote:
Sun Apr 25, 2021 11:53 am
Hi John,
this is the one I bought and I like it: https://de.aliexpress.com/item/32906393 ... 4c4dSHExGM
It actually has a dark tip insert so it's not plain steel, but I can't determine whether it's diamond or carbide. It works! :D

Bob
That is very reasonably priced. A steel ruler and you are in business.

Have you tried to cut out a square or circle in the center of a cover slip?
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Re: Best Practices Drymounts

#10 Post by MicroBob » Mon Apr 26, 2021 3:18 pm

I bougth the pen to label a stack of slides for paraffin sections. I label them in advance and take notes in a book to make sure I know what they are.
Last I used the pen to cut 20x20 cover slips in quaters. I used them for a diatom incineration cleaning method that works best with small rectangular cover slips.
Straight cuts are simple, making a cutout in the center should be nearly impossible.

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Re: Best Practices Drymounts

#11 Post by linuxusr » Wed Apr 28, 2021 3:43 am

@Bob
I like the idea of adhesive tape for a mount intended for a short time (days, weeks). It occurs to me that the Scotch "transparent" tape may be thinner than a 0.17 mm coverglass.

Can you tell me more about the diatom adhesive that you blow on? Name? Where do I find it?
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Re: Best Practices Drymounts

#12 Post by linuxusr » Wed Apr 28, 2021 3:45 am

Sorry, MicroBob
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Re: Best Practices Drymounts

#13 Post by microcosmos » Thu Jul 01, 2021 10:59 am

Is there an adhesive tape that is isotropic and wouldn't give a signal under a polarizing microscope, so it can be used to mount birefringent specimens for examination under polarized light?

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