Hi All:

I'm in the process of writing an article on the bog iron industry in the 
New Jersey Pine Barrens for my website, and had a few generic questions 
related to blast furnaces, forges, and slag. If someone can point me to 
some good source material, or even answer my questions, I'd be much 
indebted.

Firstly, there is definitely a difference in the type of slag that is 
produced by a blast furnace and a forge. Within the scope of furnace 
slag, it appears that the slag is different depending on whether the 
furnace used the cold blast method, or the hot blast method. From my 
understanding, cold blast furnaces tended to produce very rocky, 
metallic slag that in some ways resembled pyrite in texture and form. 
Hot blast furnaces produced slag that is almost glass-like. Is my 
assumption correct?

Forge slag seems to look just like you would expect a pool of cooled 
iron to look like. It is smooth in texture, without a lot of visible 
impurities (ie: no unburnt charcoal, etc.) Are there other ways of 
telling if forge slag is in fact forge slag?

I have seen varieties of cold blast slag and forge slag, and what I 
assume to be hot blast slag, although it was at a site that I was 
unaware used hot blast technology.

Secondly, when it comes to forges, it seems that many had both a 
stamping mill as well as a tilt hammer. The thing that I am unclear on 
is what the main difference in the finished product of both were. I have 
scoured "Early Forges and Furnaces in New Jersey" but it is pretty 
unclear to me what the main differences are. If anybody can shed some 
light on the subject, I'd really appreciate it.

Thanks!
Ben Ruset