Hi all, The inclusions you mentioned are not caused by any of the
things you have mentioned.
I have seen castings with 'investment inclusions' . I noticed a tiny pinhole on the surface of the casting and start to excavate a bit with a needle or tiny ball burr and opened up a small crater filled with investment. I have seen this caused by two things. Improper sprueing ( the sprue wasn't totally connected leaving an undercut that upon investing gets filled with a very thin fin of investment) and from pierce out work (windows or azures) in the model that taper to a very sharp point.
These inclusions, when you analyze what has been stated is actually
caused by a tiny airpocket inside the wax. when a wax with this type
of inclusion is invested, a tiny hole is caused when it is invested
under vacuum and due to the vaccuum, the investment finds it’s way
into the air cavity in the wax .This, then becomes aninvestment
inclusion in your casting. This is the only way that this happens…
Look at your wax with magnifiers and if you see any white spots near
the surface… these are tiny air inclusions that will be filled with
Hope this helps.
Presently in Thailand and will probably be visiting with Dr hanuman
in Bangkok soon.
** Hanuman’s Response **
Looking forward for a dinner together on the banks of the JaoPraya river