Dear All and John,

Thanks.  I figure that we all have expertise to contribute here.  There are much better smiths than I will ever be and folk who know much more about, say, electricity or IT or propane forges than I do.  My experience and expertise lets me throw into the discussion a perspective that most people do not have and I am happy to share what I can with my IFI friends/family.  As you say, there is a lot of misunderstanding out there about the law, both good and bad.  If I can clear up some misunderstandings or suggest a solution to a problem I feel that is what I am here for.

"By hammer and hand all arts do stand."

Did we ever find out what the blobs were?

I think arkie’s supposition about slag and overflow from thermite welding was most accurate. 

I agree with JHCC agreeing with me....LOL!!

If one watches videos of thermite welding there is indeed an overflow and it runs out of the mold into a puddle next to the rails.....looks like slag from a furnace.

The raised shape shown in the second photo might be the shape of an overflow pan that the slag flowed into.

Joey van der Steeg did a video on this. 
 

 

Thanks from me too George. I'm interested in most anything well explained and having a handle on things legal might come in handy some day.

You know I'm beginning to wonder if there's anything Joey won't forge into a knife.

I concur, thermite weld slag, fits the conditions and explains it. 

Frosty The Lucky.