New method for mounting radiolaria and probably other objects

[MicroBob]

Hi together,
when talking with a young female apprentice about artificial finger nails I became interested in UV adhesives. Later I found LOCA, an UV adhesive used in smartphone display repairs and looked for promising objects to test it. I found that it is a very good mounting medium for radiolaria and prepared it as a topic for a group meeting. We had especially nice deep sea radiolaria material so the esthetic aspect was cared for too. It was a very lively meeting and the marine zoology professor who held a lecture afterwards regretted that he didn't have the method in his active times.
I post a link to the german description of the method. When I find that the is much interest in it, I might make an english version from it too. It would be nice if you give it a try, also for other objects, and post your results. LOCA is not useful for diatoms, but it may be interesting for insect parts and other thicker objects. I have no experience about the influence on stains so far. It would be nice to find out the pH value of it, but for this platin electrodes would be needed as far as I know.

Here is the link:http://www.mikrohamburg.de/Programm/Pro ... 181117.pdf

Bob

[MichaelG.]

Many thanks for this, Bob
I purchased some LOCA a couple of months ago, but have not yet had the opportunity to try it.

Your results are most encouraging !!

I look forward to your 'authorised translation' but meanwhile, I will see what DeepL can do.

MichaelG.

[MichaelG.]

Bob,

A related question, if I may ...

I have looked at the referenced Radiolarian paper on your site:
http://www.mikrohamburg.de/Goeke/Radiolarien_gesamt.pdf
and have translated the nine-step process for preparation:

1. gently break the sample into pieces about the size of hazelnuts.
2. loosening the material with a saturated solution of sodium sulfate (Glauber's salt) in water by crystal blasting.
3. removal of the lime with diluted hydrochloric acid.
4. washing potassium chloride with water.
5. carbonization of the often present organic material with concentrated sulphuric acid to carbon.
6. cold oxidation of the carbon with potassium permanganate.
7. removal of the resulting manganese dioxide with oxalic acid.
8. washing out with water and separation of the radiolarians by fractio-nation decantation or sieving with water.
9. storage of the clean material in alcohol (not in water).

This all seems reasonable, except for the phrase "by crystal blasting" [which is the machine translation of "durch Kristallsprengung"]
... Could you please clarify ?

Thanks
MichaelG.

[Hobbyst46]

Bob,

A related question, if I may ...

I have looked at the referenced Radiolarian paper on your site:
http://www.mikrohamburg.de/Goeke/Radiolarien_gesamt.pdf
and have translated the nine-step process for preparation:

1. gently break the sample into pieces about the size of hazelnuts.
2. loosening the material with a saturated solution of sodium sulfate (Glauber's salt) in water by crystal blasting.
3. removal of the lime with diluted hydrochloric acid.
4. washing potassium chloride with water.
5. carbonization of the often present organic material with concentrated sulphuric acid to carbon.
6. cold oxidation of the carbon with potassium permanganate.
7. removal of the resulting manganese dioxide with oxalic acid.
8. washing out with water and separation of the radiolarians by fractio-nation decantation or sieving with water.
9. storage of the clean material in alcohol (not in water).

This all seems reasonable, except for the phrase "by crystal blasting" [which is the machine translation of "durch Kristallsprengung"]
... Could you please clarify ?

Thanks
MichaelG.

About stage 2: I think that it is not abrasion, but more like "exploding". Immersion of the raw solid material (fossils) in a saturated solution of a salt (sodium sulfate, magnesium sulfate etc), than drying. Salt that has been embedded in the narrow pores expands and thus breaks the large fossil piece into small fragments. That is my opinion.

About stage 4: the original text actually means: remove the potassium chloride by washing with water. But the previous step with HCl is supposed to remove Calcium salts, not Potassium (Kalium) salts, IMHO. So, perhaps a small misnomer in the original text.

[MicroBob]

Hi Michael and Doron,
thank you for your thorough reading of Gerhard Gökes instructions!
Doron, you are right, calcium is removed so the text is not correct here. I will have it checked and corrected. Funnily the error has not been found in more than 20 years!

The Kristallsprengung has to be carried out as you wrote, Doron, let the Glaubersalz - solution sink in, let dry, repeat. It probably als works just as well with repeated frosting, using a peltier element, a PC processor cooler and a time switch (Or just patiently by hand with the household freezer). One guy used weak ultrasonic waves and a fine sieve. The material was not so great afterwards, but Barbados radiolaria often are this way.

I still have not used this process on by piece of Barbados material since I have easier to access radiolaria material.

Bob

[Hobbyst46]

Hi Bob

Thanks for posting the protocol. LOCA is not available worldwide, but perhaps other UV-curable adhesives can be used. Besides NOA61, that has an (unnecessary in this case) high RI and is not inexpensive, there is gel nail polish. I have been using clear transparent gel nail polish for sealing slides; its RI is lower than that of glass. Based on a 14-month experience, gel nail polish adheres to the slide without peeling, and does not become yellow or cloudy. Regretfully I do not have Radiolarians to try; could they be found in shallow marine beach water or sand (depth 0.5-1m) ?

Incidentally, I found that there are standard (ASTM) tests of the hardness or similar properties of materials, based on the "crystal breaking" with sodium sulfate and similar salt solutions. Just a note.

[MicroBob]

Hi Doron,
LOCA is perhaps not available where there are no smartphones around.
It may be sold under a different name of cause. LOCA is just Liquid Optical Clear Adhesive, so not a real brand name or so. You might ask a phone repair shop.

Radiolaria live in salt water and they are there in the mediterranean sea. What I don't know is how long you have to look for them until you have success. In the deep sea at below ca. 5000m the water dissolves lime and not much holds itself in this climate. So much of what can be found there is radiolaria skeletons.

I have used two other UV glues: One glue to stick artificial finger nails on and on for the outside of them. The glue was interesting, but I found that it hardened to a really hard condition and tended to jump off from too much mechanical tension. It was possible to make nice clear lenses with it though. These UV glues give off a terrible stench so for safety reasons I wouldn't recommend to get them into contact with the skin or use them for these stupid artificial finger nails. Better fix them with pop rivets or the nail gun!

There must be more interesting UV glues for microscopy. LOCA TP 2500 is quite soft, the finger nail poison is extremely hard, something in between maybe.

Bob

[Hobbyst46]

Hi Bob
I think I understand the Hamburg Radiolaria mounting protocol, but I am not clear on steps 7-9.
First, about the olive green coverslip-holder. Is it something you designed and 3D printed? Perhaps a piece of Lego could be modified (with a mill or drill-press) to perform a similar function?
In step 7, the coverslip is placed on an M8 nut. Why not back on the green holder?
In step 8, do you place the slide over the coverslip, make it touch the coverslip so the adhesive with the pre-glued Radiolaria are sandwiched in between, then pick up the slide, with out turning it over?
In step 9, do you place the slide, coverslip facing downwards, on the hot plate ?
I am somewhat confused because, theoretically, once step 6 is over, the Radiolaria is glued to the coverslip and the glue has been cured, so perhaps in the latter steps, the slide could be handled straight (slip facing up) or inverted (slip facing down).
What am I missing?

[MicroBob]

Hi Doron,
I can clarify this:
The holder is 3d-printed, it supports the cover slip against sideways movement when applying and spreading the first half drop of LOCA. I my self dont neccessaryly need it.
After the first UV cure the radiolarias are fixed. I place the cover slip on the nut to have free access. The coverslip sucks itself to the slide and the slide can then be turned around since the radiolaria are already fixed. Then I place it cover slip up on the hot plate to not weight the radiolaria with the weight of the slide.
It only takes about 6 minutes to make a slide, mostly waiting .

Bob

[Hobbyst46]

Thanks for the clarification!

[MicroBob]

About stage 4: the original text actually means: remove the potassium chloride by washing with water. But the previous step with HCl is supposed to remove Calcium salts, not Potassium (Kalium) salts, IMHO. So, perhaps a small misnomer in the original text.

Hi Doron,
thank you for your thorough reading and for pointing this out! The error is corrected now. It is really funny that it has taken 25 years or so to find it. Gökes article is the standard text in german language for hobbyists who start to work with radiolaria. So its good to have it correct.

Bob

[MichaelG.]

Many thanks for the update, Bob and Doron

MichaelG.

[Radazz]

I’ve had some success mounting diatoms and insect parts with this lacquer.
The glue can take 30 min or more to harden in one of those nail hardening chambers, (basically a tunnel with 4 uv bulbs.)

Un-even curing can cause shadows around thick specimens like insect parts.

I’ve also used it to glue down the edges of coverslips for dry mounting crystals for POL, or butterfly wings.
Radazz

[MicroBob]

Hi Radazz,

thank you for posting your experiences!
LOCA is probable usable with advantage for several other mounting methods.
For smartphone repair the silicone-like hardness that I got after 2 minutes in the finger nail UV lamp is just right because it would be possible to remove a broken glass without damaging the display below it. So I didn't try what happens when curing it longer. I will do that now.
Fish scales, butterfly scales and wings, minerals might work with LOCA. With crystals it probably depends on the chemical properties of the crystals and whether they react with the LOCA.

Since not all old mounting media are still availabe (e.g. the much beloved CAEDAX) and most are difficult to obtain it is nice to find something new that enlarges the available portfolio.

Bob

[Hobbyst46]

I’ve had some success mounting diatoms and insect parts with this lacquer.

Hi Radazz, how visible were the diatoms in the lacquer, in comparison to other mounting media?

[Radazz]

I’ve had some success mounting diatoms and insect parts with this lacquer.

Hi Radazz, how visible were the diatoms in the lacquer, in comparison to other mounting media?

I just mounted some in balsam, but the slide will take a few days to harden up enough to hang it upside down in the inverted microscope. I will then do a comparison in bright field of the two media.

I’m re-arranging the lab to get the BX40 available as well.
Anyroad, I will do this comparison, and the Hoffman/phase contrast comparison sometime in the next couple of weeks..

However, here’s an image of diatoms I mounted in UV lacquer.
Thin glue from a kit for making trout flies. Cured 6 min in nail chamber. Actually a UV flashlight held close works faster, but you need to keep moving or it will cure unevenly.

Olympus IX70, 20x HMC, no stacking.


Radazz

[Hobbyst46]

Thanks! and it looks very good!

[Radazz]

And thank you, sir.

[Hobbyst46]

Here is a source for the method of breaking a fossil with a saturated salt solution - analogous to the use of sodium sulfate. Citation from a note in Nature Vol 110, August 1922. The product though are fragments of radiolaria. Ancient articles have their flavor.