110
4.
EMBEDDING
Earlier efforts to employ Araldite 502 embedding included the suggestion of Finck (1960) to use a different accelerator (benzyldimethylamine).
Mollenhauer (1959) employed a vacuum oven at 80°C for a few minutes
to remove bubbles from loaded capsules. Presumably, this removed traces
of alcohol and aided impregnation. He also completed polymerization in
a nitrogen atmosphere (48 hours at 80°C). This writer has not had experience with these variant techniques.
D. Moore, in New York, made a major effort during the late 1950's to
develop Araldite 6005 as an embedding resin. He chose this since it was
not a blended resin, and because it had the lowest molecular weight of
any unmodified resin available in the United States at that time. He
analyzed the effects of various possible hardeners and accelerators and
selected n-benzyl dimethylamine as the best choice for the latter purpose.
His findings were never officially published, although they have been
available in mimeographed form along with a kit of supplies sold through
Cargille and Sons, Little Ferry, New Jersey. Moore himself recognized
difficulties with his method which he attributed mainly to problems of
impregnation. However, Richardson, Jarett, and Finke (1960) apparently
achieved good results with a very similar formulation after introducing
toluene as an intermediate solvent. In the meanwhile, though, Luft's reliable method had become widely known, even before publication, and
interest in Araldite 6005 died away.
Some laboratories blend Araldite resin with minor quantities of the
water-soluble epoxy resin, Durcupan (Chapter 4.16). This somewhat
softens the final embedment, and is said usually to improve its cutting
characteristics. Also, there is some reason to believe that electron stains
then penetrate more easily (Chapter 7.2).
4.11. Epon Embedding
Partly because of early difficulties in handling Araldite, American investigators sought other epoxy resins that might be easier to use. Both
Luft (1961) and Finck (1960) explored the use of Epon 812 (Shell Chemical Corp., San Francisco, California). (An identical resin is sold in Europe trademarked Epikote 812.) This is an aliphatic resin in contrast to
the aromatic Araldite. The monomer of Epon has an advantage over
Araldite in being quite fluid rather than decidedly viscid and, thus,
might be expected to penetrate tissue blocks more easily and rapidly.
4.
EMBEDDING
Earlier efforts to employ Araldite 502 embedding included the suggestion of Finck (1960) to use a different accelerator (benzyldimethylamine).
Mollenhauer (1959) employed a vacuum oven at 80°C for a few minutes
to remove bubbles from loaded capsules. Presumably, this removed traces
of alcohol and aided impregnation. He also completed polymerization in
a nitrogen atmosphere (48 hours at 80°C). This writer has not had experience with these variant techniques.
D. Moore, in New York, made a major effort during the late 1950's to
develop Araldite 6005 as an embedding resin. He chose this since it was
not a blended resin, and because it had the lowest molecular weight of
any unmodified resin available in the United States at that time. He
analyzed the effects of various possible hardeners and accelerators and
selected n-benzyl dimethylamine as the best choice for the latter purpose.
His findings were never officially published, although they have been
available in mimeographed form along with a kit of supplies sold through
Cargille and Sons, Little Ferry, New Jersey. Moore himself recognized
difficulties with his method which he attributed mainly to problems of
impregnation. However, Richardson, Jarett, and Finke (1960) apparently
achieved good results with a very similar formulation after introducing
toluene as an intermediate solvent. In the meanwhile, though, Luft's reliable method had become widely known, even before publication, and
interest in Araldite 6005 died away.
Some laboratories blend Araldite resin with minor quantities of the
water-soluble epoxy resin, Durcupan (Chapter 4.16). This somewhat
softens the final embedment, and is said usually to improve its cutting
characteristics. Also, there is some reason to believe that electron stains
then penetrate more easily (Chapter 7.2).
4.11. Epon Embedding
Partly because of early difficulties in handling Araldite, American investigators sought other epoxy resins that might be easier to use. Both
Luft (1961) and Finck (1960) explored the use of Epon 812 (Shell Chemical Corp., San Francisco, California). (An identical resin is sold in Europe trademarked Epikote 812.) This is an aliphatic resin in contrast to
the aromatic Araldite. The monomer of Epon has an advantage over
Araldite in being quite fluid rather than decidedly viscid and, thus,
might be expected to penetrate tissue blocks more easily and rapidly.