MicrobeHunter.com Microscopy Forum

Hello,

as the title says I have a question regarding the formula for a glycerin gelatin mounting medium. I'm inclined to make my own mounting medium, and have spent quite some time looking for different formulas and ingredients. However, I've read that in order to founction permanently, the medium needs something that kills bacteria and mould (antiseptic). In the formula you can read by clicking the link below, the author, who seems to know what he is talking about, suggests listerine. Do any of you have any experience in this?

Here is the formula (Kaisers):
water - 21g
glycerin - 12g
gelatin - 7g
listerine - 2g

http://www.microscopy-uk.org.uk/mag/ind ... part4.html
Best regards,
Joab

Joab, I don't do permanent mounts so can't help you.
Maybe someone else on this site can but my advice is try it, see what happens, and if it doesn't work modify the recipe and try again. Part of the enjoyment is trying and learning

Hi Joab - I've been using a batch I made myself complete with Listerine (as advocated by the late Walter Dioni) for about 3 months now - I store the little cubes I cut the jelly into (with scissors) in a plastic pot with a lid in my cabinet and it's completely fresh and perfect to use - the Listerine works perfectly! It has a very slight greenish-tinge (not when you use it however) and smells rather nice too!
Here it is... I hope this helps a bit Joab.

Walter Dioni's articles are simply superb - I have read them all about 10 times over and learned a huge amount! I've got his small book too and it's worth buying - also it's a thank-you to the late WD and his family for his inspiring work!
Trust implicitly what he says - see my onion-skin posts - all based upon Walter's examples... He is (was) a top top fellow in the home microscopy field.
Enjoy yourself!

Thank you John B, that is some excellent information! Both about listerine and storage - you've definitely taken me one step closer to trying this.

Yes indeed, the more of his articles I read the more I understand the value of them!

Joab wrote:Thank you John B, that is some excellent information! Both about listerine and storage - you've definitely taken me one step closer to trying this.

Yes indeed, the more of his articles I read the more I understand the value of them!

Why not try some permanent mounting with something that needs virtually no processing.. I started to learn (permanent) mounting using pollen - simply tap some (make sure its dry) onto a slide, warm your slide (I place mine on a cup-warmer bought for about £5 new via Amazon), melt some of your glycerin jelly (in a small pot) in the microwave or via a water bath, drop about 4 drops onto your (warm) pollen slide, apply cover-slip and lightly press to spread GJ to edges of the cover-slip - don't worry if excess exceeds edges of the cover-slip, it is easily removed when set. Remove from heat and leave to set (about 30 minutes at RT) - you now have a permanent slide! When using GJ all must be kept warm at about 40 deg C for a smooth process.
Do the above using nail-polish instead of GJ and you'll also get a great permanent slide! Just make sure you don't use too much as it's not as easy to remove as GJ - you won't need any heat for NP either!
Good luck

p.s I worked through WD's routines using onion-epidermis and learned a huge amount!

A rather late post but given I am going down this road you can seal the edges of a glycerin jelly mount with nail polish and it further improves the longevity of the slide and prevent seepage over time. It all depends on how long you intend to keep the slide.

In labs phenol (or thymol) would usually be used as the preservative, but as amateurs we often struggle to get such chemicals, so folk like Walter have found substitutes that work as well, that are easily available.

I know that laws in some States, and Australia in particular can be quite limiting, and here in the UK they are clamping down on things like acids now, which is bad news for diatomists. You can still get 9% (30 vols) hydrogen peroxide here at a chemist shop, but no stronger.

Mike

photomicro wrote:In labs phenol (or thymol) would usually be used as the preservative, but as amateurs we often struggle to get such chemicals, so folk like Walter have found substitutes that work as well, that are easily available.

I know that laws in some States, and Australia in particular can be quite limiting, and here in the UK they are clamping down on things like acids now, which is bad news for diatomists. You can still get 9% (30 vols) hydrogen peroxide here at a chemist shop, but no stronger.

Mike

I made a glycerin jelly batch and used Cepacol. It has been in a refrigerator at 40F for 3 years and still has not grown anything!! LOL

Hi Joab

A point to learn from the excellent Walter Dioni reviews is that, although there are some general-purpose formulations, the mountant must be compatible with the specific specimen, and sometimes one medium around the specimen should be gradually changed.

I received a small sample of a culture of phytoplankton ("alive" diatoms). They were swimming to and fro very fast. I made two slides on one with a tiny drop of an aqueous solution of gelatine ("Dil") and on the other gelatine in excess (Conc). Sealed with nail polish. After a few days, in the first slide they look the same as when alive and kicking, but on the Conc, they are deformed and shrunk. So I learned a lesson.

Incidentally, I have tried gel nail polish ("top gel"), the type that is cured by light, for sealing. It is less convenient to apply than nail polish, however the seal is very stable and much more resistant against organic solvents.

When mounting "live" specimens and sealing with nail polish I would think you would want to be concerned with solvent exposure. Microbehunter magazine has a good article on pollen and medium effects. For me Glycerin Jelly is a compromise given it has a refractive index of ~1.44 which represents a compromise compared to other popular mounting agents. It's simplicity of use and the ability to preserve organisms alive while restricting movement may be an advantage.
I have Walter's book. It is an excellent read.

Glycerin gelatin mounting medium that is tried and tested.

I'd like to share with you this formula for making glycerin gelatin permanent mounts.

60% glycerine
2% gelatin
5% formalin

and recently I have been examning a slide of Stephanocerus sp. mounted in this medium in 1918, it's a lovely preparation and collected and mounted in May 1918 is over 100 years old, I'd call that a permanent mount.

It is by Eric Doddrell Evens and belongs to the Quekett Microscopical Club.

His logic for this ratio was that at 60% the glycerine has an osmotic pressure that prevents decay, therefore there is no need to add an aniseptic or other preservative, the gelatine provides a framework and the formalin 'sets' the gelatin, thus holding the specimen in position. The secret to keeping this intact is the degree and thoroughness of sealing the cell. For this he used a shellac based ringing material and the details are in one of the QMC journals of 1961 (I think).
In a PMS notebook he describes how he rings mounts at approximately two weekly intervals until he has sufficient layers to effect the seal (I get the impression it is about 10 layers) and finishes off with shellac and lampblack. Not a quick fix, but if you've seen the precision and beauty of his slides you'll know it is worth the effort.

My point is that it is perfectly possible to make long-lived mounts in this medium but you need to understand what is necessary for them to be successful.

BTW: I've only seen slides like this, it's on my bucket list to have a go at it, but I need a lot more time to do it properly. In the meantime I'll just look and admire.

JackyMac wrote:Glycerin gelatin mounting medium that is tried and tested.

I'd like to share with you this formula for making glycerin gelatin permanent mounts.

60% glycerine
2% gelatin
5% formalin

and recently I have been examning a slide of Stephanocerus sp. mounted in this medium in 1918, it's a lovely preparation and collected and mounted in May 1918 is over 100 years old, I'd call that a permanent mount.

It is by Eric Doddrell Evens and belongs to the Quekett Microscopical Club.

His logic for this ratio was that at 60% the glycerine has an osmotic pressure that prevents decay, therefore there is no need to add an aniseptic or other preservative, the gelatine provides a framework and the formalin 'sets' the gelatin, thus holding the specimen in position. The secret to keeping this intact is the degree and thoroughness of sealing the cell. For this he used a shellac based ringing material and the details are in one of the QMC journals of 1961 (I think).
In a PMS notebook he describes how he rings mounts at approximately two weekly intervals until he has sufficient layers to effect the seal (I get the impression it is about 10 layers) and finishes off with shellac and lampblack. Not a quick fix, but if you've seen the precision and beauty of his slides you'll know it is worth the effort.

My point is that it is perfectly possible to make long-lived mounts in this medium but you need to understand what is necessary for them to be successful.

BTW: I've only seen slides like this, it's on my bucket list to have a go at it, but I need a lot more time to do it properly. In the meantime I'll just look and admire.

But surely, in the very formula you quote, the formalin is there to inhibit growth of life forms, the same role that thymol or phenol plays?

Thymol is preferred by many users as phenol can alter the colour of stains.

As I understand it, one of EDE's ideas was to match the formula of the mountant used to the RH of the environment it was to be kept in. Not sure of this could be controlled though (external environment).

His notes indicate that the formalin was to denature the gelatin and stop the subject moving. I'm guessing it was when he joined the PMS and his slides were making long journeys that shifting specimens became more of an issue. But he used the formula long before that.

The same formula minus the formalin was used very successfully during his mounting career. He also tried adding various materials like thymol to avoid microbial degradation but in later years settled on the formula I quote. Most of the other 'preservatives' seem to result in discolouration of the mounts so he then left them out.

For a while he varied between 55% and 60% glycerol, I think this was when he was juggling with the RH. Both can give good mounts.

I suppose another thing on my bucket list is to look closer at the details in his notes and compile all he said about this medium - it tracks over quite a few notebooks in one way and another.

JackyMac

The glycerine, gelatin and formalin add up to 67%. I presume the other 33% is water?

Tom