You have already received suggestions on this. I would add to be sure that you
rinse the block well before cutting, especially if using a "solid" rather than a
disposable knife blade.
If you are finding small areas of calcium,  this may be due to inadequate volumes
of decalcification fluid or a lack of agitation during the demineralization
process. I have seen happen with teeth and occasionally with large bone samples a
partial decalcification, the solution becomes saturated with mineral salts, and
mineral then becomes redeposited as spherical bodies near the areas still not
decalcified. While placing the block in fresh solution can remove the mineral
salts, the areas in which these spherites were deposited still show a different
staining.
You may want to carefully examine the areas, especially if in the denser regions
of the bone, to make sure that you have not introduced this artifact.
Barry

Decalchem@aol.com wrote:

> In a message dated 4/12/99 8:41:51 PM, emry@u.washington.edu writes:
>
> <<I am cutting decalcified specimens of jaw joint in paraffin blocks.  On
> occasion, I run into what appears to be tiny lumps of calcium that leaves
> holes across the specimen as it is pulled across the knife.  Is there a
> way to deal with this IN the block?>>
>
> You can decalcify the surface of the block.   We find it best to place a dish
> of your favorite decalcifier on ice and place the block face down in the dish
> for 10-20 minutes.   Then rinse the block in cold water and resume cutting.
> All the while it is best to keep the block wet and cold.   Hope this helps.
> For futher information check our website at http://www.decal-bone.com
>
> Cliff Berger
> Decal Chemical Corp
> 1-800-428-5856
> email:decalchem@aol.com
> http://www.decal-bone.com