MicrobeHunter.com Microscopy Forum

Hi together,
quite often the topic arises of which mountants to use and where to get them. Often stuff like nail polish (where does this idea come from? ) is tried, discovered as not very usable and abandoned. In some countries a variety of proven mountants is available but this is by far not the case everywhere.
What properties should a mountant have?
- Refractive index near that of the cover slip, 1,52
- good transparency
- low shrinkage
- acceptable solvent
- low acidity to protect stains
- good adhesion to glass
- tolerance towards traces of water
- fast curing
- acceptable intermedium
- good long term stability
...

There is a mountant where the ingredients are fairly widely availabl eand that is cheap to make: Dammar /Damar resin. It is a natural pant resin and can be dissolved in xylene. It ticks a lot of the boxes above, but of cause not all. Dammar resin is used by artists as the base of a varnish and in raw form available in artist shops. There are well preserved slides of much more than 100 years that have been made with this mountant.

There are a few problems though:
- There are not many solvents that work well, xylene does
- It contains about 1-2% of mixed djungle dirt
- dissolved to a useable consistency it is impossible to filtre at room temperature.

A member ouf our group found a way to make this nice mountant in one go by means of vacuum filtering the warm resin. Due to the described difficulties advanced chemistry lab equipment has been used. One should know how to us this safely before attempting to follow this description. It would be possile to get a long with more basic equipment by dissolving in more xylene and reduce the xylene content afterwards by time consuming evaporation. Here you can find the description:

http://www.mikrohamburg.de/Tips/2022_NW ... arz_en.pdf

Bob

Thank you kindly for sharing this, I've been curious about dammar resin for a while since I hope to find a mountant that is tolerant of alcohol. I've read that turpentine can be used instead of xylene and if I understood clearly it is tolerant of alcohol in the sample; which would be handy. Have you found this to be the case?

Since Dammar doesn't dissolve well in alcohols I don't think it is likely that it will fully tolerate alcohol when dissolved in turpentine.
In my eyes Dammar is similar in use to canadabalsam, intermedium xylene, not tolerant of water. Compared with canadabalsam I would say it is a bit less variable, it has a lot less acidity and it darkens less. As far as I know it dissolves well in turpentine but I don't know how well to use it is then as a slide mountant.

For isopropanol as intermedium Euparal is nice. But this is a company secret and no one knows how long it will be available.

Thanks, Bob!

It would be interesting to hear when you try the recipe or adjust the procedure to the equipment you have available. It would also be interesting to hear how well you can get dammar and xylene in your country.

One remaining information: Dammar has green fluorescence when excited with blue, like probably all natural resins. There may be other wave lenghts. So for fluorescence microscopy some artificial resin like Eukitt or Eukitt UV is better.

I use selected high quality resin chunks and dissolve them in artist's turpentine over a warm hotplate. Let it settle for a week or so, and the haze/dirt will be at the bottom of the bottle. Just use the top layer or pour it off to another bottle. No need to filter. Go straight from pure alcohol or xylene to the mountant. Good stuff, takes a long time to set up, though.

I guess this is a much stronger mix than the artist's gum dammar varnish?
(I have used the Winsor and Newton gd varnish and it is a bit on the thin side)

The recipe I posted contains the least possible amount of solvent. It is on the border of being too stiff at room temperature. The advantage is that not much shrinkage occurs.