Do you do decalcification endpoint checks?  With the decalcifiers you are
using, and decalcified for weeks, your bone should be free of calcium, but
if you don't do endpoint checks, you will not know for sure plus
decalcifying for weeks in these solutions may ruin the staining of your
bone (called overdecalcification, a misnomer, aka overexposure to acid).   

Also what is the species? large or small animal, rodent, etc?

17% formic acid will decalcify a whole mouse head in a few days, and RDO
would do it in less time since it is a strong hydrochloric acid
decalcifier, with endpoint checks and extended processing, can cut 5 um
sections without problems.

Could be your problem is not the total removal of calcium but processing
the bone long enough to get good dehydration, clearing and most important
of all, infiltration of paraffin, preferrably with a harder paraffin ie
Tissue Prep 2 (Fisher) in order to have good sectioning, not to factor in
using extremely sharp knives, changed frequently, even after a few cuts.  

What is your processing schedule for the type (?) and species (?), size of
bone (?) you are cutting???   

At 09:50 AM 12/6/00 -0700, you wrote:
>
>Does anyone have any suggestions regarding decalcifying cortical bone?  We
>have a mandible here we've been trying to decalcify for weeks.  17% formic
>acid, then RDO (a commercial rapid decalcified).  We are still encountering
>a lot of problems cutting sections on our blocks!
>
>JACQUIE MACK
>TECH II MAIN LAB FMC
>HISTOPATHOLOGY
>PH: 670-1574
>e mail:  Jacquie.Mack@CLS.ab.ca
>
>
>
>
Gayle Callis
Veterinary Molecular Biology
Montana State University
Bozeman MT 59717-3610
406 994-4705
406 994-4303