Epoxy resins and methacrylates are often harmful. Resin blocks are harmless after curing but, if cured blocks are sawn, make sure that the dust is not inhaled.
Agar 100 – replaces Epon 812 resin, now unobtainable. The formulation of Agar 100 resin is the same as Epon, but is less viscous than many samples of Epon 812 and is more closely controlled in its manufacture. Epoxide equivalent between 148 and 150.
ERL 4221 has replaced ERL4206. It has a higher viscosity (180cps) than the previously used ERL 4206 (60cps). Ref: Ellis, E Ann, Solutions to the Problem of Substitution of ERL 4221 for Vinylcyclohexene dioxide in Spurr Low Viscosity Embedding Formulations, Microscopy Today, Vol 14, No 4, July 2006.
Technical Note
The original formulation, ERL 4206 (VCD) – DER® 736 embedding medium devised by Spurr (1969) combined very low viscosity components for rapid specimen penetration.
This embedding medium has been especially suitable for a variety of mineral and biological specimens. Since ERL 4206 is no longer available, ERL 4221 has been substituted as a replacement*.
It will work well for most users but it does have somewhat higher viscosity (180cp vs. 60cp) than the ERL 4206, which can impact some protocols employing vacuum embedding.
*Reference: Ellis, E. Ann Microscopy Today, July, 33 (2006)
A block of MEDIUM hardness can be obtained by using the following formula based on a batch of 10 grams without the flexibilizer, DER 736:
| Part no. |
Description |
Hardness |
Rapid |
|
|
Medium |
Harder |
Softer |
|
| AGR1047R |
ERL 4221 |
4.10 g |
|
|
|
| AGR1072/73/74 |
DER 736 Diglycidylether of Polypropyleneglycol |
1.43 g |
0.95 g |
1.90 g |
|
| AGR1054/55/56 |
NSA (Nonenyl Succinic Anhydride) redistilled |
5.90 g |
|
|
|
| AGR1066/67 |
S-1 (Dimethylaminoethanol) |
0.10 g |
|
|
0.20 g |
A harder block can be produced by decreasing the DER® 736 component to 0.95g in the above formula; a softer block by increasing the DER 736 to 1.90g.
ALL STEPS MUST BE PERFORMED UNDER A HOOD AND GLOVES MUST BE WORN FOR PROTECTION.
Preparation:
Care should be taken to weigh the ingredients accurately into a beaker. The quantities given in the first column are for firm blocks.
For harder blocks, decrease the DER 736 to 0.95g; for softer blocks, increase the DER 736 to 1.90g.
For rapid cure, increase the DMAE. It is recommended to add the catalyst (dimethylaminoethanol) last, after having carefully mixed the other components.
If bubbles are a problem, they may be eliminated by placing the beaker into a desiccator under a gentle vacuum.
