120
4.
EMBEDDING
only for room temperature curing, whereas benzoyl peroxide is their
recommendation for curing at elevated temperatures. Unlike Vestopal,
no accelerator is necessary. Polymerization is at 60°C.
Our own experience with pure Selectron embedments has been too
limited to allow more than tentative estimation of their properties and
virtues. Infiltration is as easy as with Vestopal. Sectioning qualities seem
good, and the fact that the hardness of the block can be varied at will
provides a procedural flexibility lacking with Vestopal. Material stains
at least as easily in Selectron as in Vestopal, and shows essentially the
same contrast. More experience will be required before we can be sure
that it has as good stability during electron bombardment.
Kushida (1960) developed Japanese Rigolac polyester resins (sold by
Riken Goseijushi Co., Tokyo) as embedding media. The stated advantages are a relatively low viscosity of the embedding mixture, and the
possibility of controlling hardness by blending different proportions of
two different resins, an 8:2 or a 6:4 ratio of Rigolac 2004 with Rigolac
70F. This is catalyzed with 1% of a benzoyl peroxide paste, and polymerized in 18-24 hours at 55 °C.
It seems likely that this is an excellent embedment, but the difficulties
of obtaining the plastic monomers is apt to prevent its widespread use
outside of Japan.
Yet another polyester plastic has been advocated for purposes of
ultrathin sectioning by Fischlschweiger (1963). This is Viapale, available
through Vianova A. G., Johannesgasse 14, Vienna. The hardness of the
final block can be controlled by mixing two different resins, and also by
blending with a hardener. The interested reader should learn details
from the original article for this writer has had no opportunity to handle
these materials.
It is evident that nearly equivalent polyester resins are available in
several parts of the world, and that at least some of these can be used as
satisfactory embedments.
4,15. Cross-Linked Methacrylate Embedding
Cross-linked methacrylate deserves to be included in the same category
as epoxy and polyester plastics for, as the name implies, all have their
most important feature in common. When methacrylate is cross-linked
it becomes essentially insoluble in common organic solvents. It is thermo-
4.
EMBEDDING
only for room temperature curing, whereas benzoyl peroxide is their
recommendation for curing at elevated temperatures. Unlike Vestopal,
no accelerator is necessary. Polymerization is at 60°C.
Our own experience with pure Selectron embedments has been too
limited to allow more than tentative estimation of their properties and
virtues. Infiltration is as easy as with Vestopal. Sectioning qualities seem
good, and the fact that the hardness of the block can be varied at will
provides a procedural flexibility lacking with Vestopal. Material stains
at least as easily in Selectron as in Vestopal, and shows essentially the
same contrast. More experience will be required before we can be sure
that it has as good stability during electron bombardment.
Kushida (1960) developed Japanese Rigolac polyester resins (sold by
Riken Goseijushi Co., Tokyo) as embedding media. The stated advantages are a relatively low viscosity of the embedding mixture, and the
possibility of controlling hardness by blending different proportions of
two different resins, an 8:2 or a 6:4 ratio of Rigolac 2004 with Rigolac
70F. This is catalyzed with 1% of a benzoyl peroxide paste, and polymerized in 18-24 hours at 55 °C.
It seems likely that this is an excellent embedment, but the difficulties
of obtaining the plastic monomers is apt to prevent its widespread use
outside of Japan.
Yet another polyester plastic has been advocated for purposes of
ultrathin sectioning by Fischlschweiger (1963). This is Viapale, available
through Vianova A. G., Johannesgasse 14, Vienna. The hardness of the
final block can be controlled by mixing two different resins, and also by
blending with a hardener. The interested reader should learn details
from the original article for this writer has had no opportunity to handle
these materials.
It is evident that nearly equivalent polyester resins are available in
several parts of the world, and that at least some of these can be used as
satisfactory embedments.
4,15. Cross-Linked Methacrylate Embedding
Cross-linked methacrylate deserves to be included in the same category
as epoxy and polyester plastics for, as the name implies, all have their
most important feature in common. When methacrylate is cross-linked
it becomes essentially insoluble in common organic solvents. It is thermo-