How to obtain nice sections for bone samples?
Embed the bones diagonally in your molds if you're able (size depending) as this will allow for the greatest amount of paraffin support. Trim them very slowly, and if need be, place the blocks into the same "slow decal" solution for additional amount of time sufficient to enable better sectioning. Start checking in half hour or 45 minute intervals; rinse the blocks well in running water and attempt to section. If they're not ready, back into decal solution they go. I feel that very wet ice helps to facilitate sectioning better than ice that is drier and fresh out of the freezer. Just be sure to blot the face of the block with gauze before attempting to cut.
There's my two cents!
Brian D. Cooper, HT (ASCP)CMQIHCCM| Histology Supervisor
Department of Pathology and Laboratory Medicine
Children's Hospital Los Angeles
4650 Sunset Blvd MS#43- Los Angeles, CA 90027
bcooper at chla.usc.edu
In my opinion the hardness of the decalcified blocks is often rather due to the paraffin-processing than the residual calcium. Especially when the tissue is decalcified really long. The hardness comes from the dehydration and "cooking" of collagen fibers. So additional decal will not help reducing the calcium, but helps to reintroduce water into the collagen-grid. And this is helpful for softening and cutting. For myself, I often scratch the paraffin on the block surface away to face the bone directly to the water. Then I let them "swim" on my water bath, until the surface is turned rather milky. After cooling again I cut in very very small steps to trim the surface. Sometimes it needs repeated swimming and cooling (and patience) to get a rather acceptable section. It is advantageous to pick them up on adhesive slides and let them dry in an 60°C oven to get rid of any residual water under the section.
Hope this helps