Porosity in steel, could it be? It happens all the time guys. Mostly with investment castings, but even in rolled or extruded parts as well. Hammer forged parts get less of it, but if the forging process is only lightly done, the porosity is only removed from the surface of the metal and not the entire part. For example an aircraft manufacturer has parts forged using a 25 ton hammer forge. This forge has enough force to compress the entire part and not just the surface in one blow. A man doing the same work by hand will take much longer, but can still do it. So even an incorrectly forged item can have porosity. Porosity can also be increased by improper heat treatment and/or improper cool or quench after casting. There is no doubt that a forged part is much stronger than the equivalent cast part. This is probably the reason why the forged khukuri's have no imperfections; some poor guy is hammering away for quite a while on these blades. If the porosity becomes large enough it is actually called voids, and is not good. But what do I know!!
Getting to things that I do know about, as follows:
Someone mentioned Baker's mix, I have a baker/butcher joke for you guys;
An old lady walks in to a butcher shop and asks for bread. The Butcher says; "lady we don't sell bread here", so she leaves.
A little while later the same old lady comes back and says; " I would like a loaf bread, please" . the Butcher, remembering her, says; " lady as I told you before, we don't sell bread here, only meat".
The lady comes back a while later and again, asks to buy some bread, so the butcher says; "lady, do you know how BREAD is spelled?" , and she says;"yes" and he says; "well, I spell it B R E f*ck A D." The lady looks at him and says; "there is no f*ck in BREAD", and the butcher says;"lady, that's what I have been trying to tell you, there is no f*ckin bread"!!!
