Preparing formvar films
This is one in a series of web pages offered as an aide to the brave
souls who cut thin sections. The purpose of this page is to provide
a few tips for obtaining clean, homogeneous formvar support films for
slotted grids.
The most common difficulty in producing formvar films is stripping
the film from the glass.
Stripping films:
Formvar films easily come off a glass support when the following
steps are taken:
- Dip a glass slide into a beaker full of supersaturated, filtered
(no. 1 paper) Alconox.
- Wipe the solution from the slide with kimwipes and polish
one slide by rubbing briskly with dry kimwipes. Blow clean with
compressed gas.
- Apply the formvar (I use 0.75 % formvar in ethylene dichloride
applied using an Effa film caster; remember, the fasterthe
solution falls the thicker the film). Let the film dry completely.
- Holding the slide with the polished side down, scrape the edges
of the slide closest to the polished surface with an acetone/alcohol
cleaned razor blade, and score the
polished surface several times close to where you are holding the
slide. Gently blow clean.
- Holding the slide at a 45 degree angle to the surface of a water
bath, slowly lower it up to the score marks on the polished surface,
pausing for an instant as the slide first touches the water.
Recommendations:
- Wear cleaned, plastic gloves during the entire procedure.
- Rinse the water bath with alcohol and water before filling.
This page prepared by Ed. White who was fortunate to have
an advisor who told him how to make good formvar films. For questions
or clarifications contact Ed. White at: wisrael@bgu.ac.il
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