Inclusion Polymerization: problems (Epoxy resin)

Polymerization problems

Incomplete polymerization of blocks (soft blocks) could occur owing to inaccurate weighing of Epoxy Kit components, inadequate mixing, improper temperature setting of oven, insufficient baking and out-of-date accelerator. If the blocks do not harden sufficiently after a few more hours of heating, then cells or tissue kept in reserve must be processed.

Many laboratories use Araldite or Epon because they feel that they are more reliable and easier to use.

One can try increasing infiltration time or more gradually increase the percentage of resin during the infiltration phase. If the soft block represents the only available material, then one can cut away as much of the plastic as possible, and soak the block in sodium ethoxide on a rotator for 24 h at room temperature. Sodium ethoxide is prepared by adding NaOH pellets to ethanol until saturated. The solution is stored overnight before use and can be kept for months. The block is rinsed in four changes of ethanol and then processed as usual. The usual cause of brittle blocks is poor dehydration. Make sure reagents are pure, concentrations are correct and dehydration times are sufficient.