I have a UK 1919 half penny with an irregular blob shaped indentation on the reverse. I think I have seen this type of thing described elsewhere as a flaw caused by a puddle of oil.

Do you think this is indeed a flaw caused at time of minting, or something else?

Thanks,
spirospero

If there's a flattened area on the other side, it could be after mintage damage.
If not, it could be cause by grease or other material, like scrapmetal.

A picture would be more conclusive, i guess

Regards

Jos

It is good to get this kind of feedback from people with more experience.

I don't belive that there is any flattening on the other side, but will double check.

I will also try to find time to add a photo.

Thanks,
spirospero.

Does the "blob" look like the King's head? For some George V coppers, the obverse "uses up" so much metal that "ghosting" occurs on the reverse, where there is a depressed area.