3/24/97
I was wondering if those of you who successfully make your own
holey grids for stigmation would care to share the method. I've been using
glcerol and 0.25% Formvar (old bottle) and while I can produce small, nice
looking "holes", on close inspection they're film. There are some true
holes, but few and far between. Any suggestions? Many thanks in advance.
Dwight Beebe E-mail: beebed@ere.umontreal.ca
Institut de recherche en biologie vegetale Voice: 514-872-4563
Universite de Montreal FAX: 514-872-9406
4101, rue Sherbrooke est
Montreal, Quebec H1X 2B2
Canada
We historically have made our own holey films, because we could not buy
good holey support films from any manufacturer. Without question, it is an
art, and most of the time a major pain in a posterior region. I would be
happy to send you the detailed instructions we have found to be most
reproducible.
Recently, however, we purchased some holey films from SPI, which have been
uniformly *gorgeous*. They are thin, clean, a large fraction of holes etc.
Probably equivalent to the best I have ever made. I don't recall the
price, but my impression is that I can't make them as cheaply, so why
bother.
Highly recommended.
allardlfjr@ornl.gov
Larry Allard
I know of two methods of preparing holey films. The first is to shake up a
mixture of liquid soap and water and Collodion until it froths, then drop a
drop or two on the surface of distilled water. Lay the grids on top of the
Collodion layer, pick up with a filter paper, dry and carbon coat. Put the
grids in a Jaffe washer with cloroform for 48 hours to remove the Collodion.
The other method, if you have Nucleopore type filters, is to carbon coat a
strip of Nucleopore filter film, place a square of the coated filter on the
grid sitting on a nickel mesh on the surface of the Jaffe washer full of
cloroform, wait 48 hours to dissolve the Nucleopore, dry grids. The holes in
the Nucleopore will be now be holes in the carbon coat.
I must admit I have not tried the first method myself, but someone in my lab
did, years ago.
Mary Mager
Electron Microscopist
Metals and Materials Eng., UBC
6350 Stores Rd.
Vancouver, B.C. V6T 1Z4
CANADA
tel:604-822-5648, fax:604-822-3619
e-mail: mager@unixg.ubc.ca
I use a method by Kuga and Brown from Philips Electron Optics Bulletin
v126, p.19 (1989) to make lacy formvar grids. First a note of caution. I
use dichloroethane as my solvent for the formvar resin. After having much
difficulty in preparing my films, I was told that when exposed to light,
dichloroethane slowly forms HCl in the solution. The HCl destroys the
integrity of the formvar polymer. Solution: store the formvar solution in
a brown bottle in a dark cabinet.
Method:
- I use 0.25% formvar solution in dichloroethane and freshly cleaved mica
sheets as a substrate. The formvar lifts off the mica much easier than
from glass microscope slides.
- Dip the mica into the formvar solution, wick off excess on a paper towel,
then breathe heavily on the mica for about 5 seconds while it is still wet.
The moisture in your breath condenses in the solution. Caution: Don't
inhale!
- When the mica has dried, score the edges and float off on water.
- Place 200 mesh TEM grids on the floating film. The area with the best
holes will appear milky.
- I then take saran wrap, stretch it tightly across the mouth of a small
(~100ml beaker), and press it down at a slight angle onto the floating
formvar film. The film will stick to saran wrap and you can easily pick it
up off the surface of the water.
- After the film has mostly dried, pick up the grids from the saran wrap
"drumhead" and place them on filter paper.
- The film will have many "pseudoholes" that have a thin residual film
across them.
- Following the method of Kuga and Brown, by heating the film to about the
T(g) temperature you can break these holes open. The time and temperature
are critical. I place the bare filter paper in a small lab oven (not in a
petri dish; it has too much thermal mass) at 110C for 12 minutes.
- I then coat both sides with carbon to stabilize the formvar lace.
I can easily make 50-100 grids in an hour (exclusive of the carbon
coating). These grids make wonderful supports for looking at fine
particulate dispersions.
Cheers, Henk
Henk Colijn colijn.1@osu.edu
OSU Campus Electron Optics Facility
two years ago. At that time John Gabrovsek (gabrovj@ccsmtp.ccf.org) gave
the following reference: Baumeister & Seredynsky, Micron 1976, Vol 7, p.
49, and Jane Fagerland (fagerland.jane@igate.abbott.com)gave this one:
Elsner, Proceedings, 29th EMSA Meeting, p. 460. Both methods were said to
work satisfactorily. You might try contacting these people for more
details.
Wilbur C. Bigelow, Prof. Emeritus
Materials Sci. & Engr., University of Michigan
Ann Arbor, MI 48109-2136 e-mail: bigelow@umich.edu;
Fx:313-763-4788; Ph:313-764-3321