dumb coke question, but I gotta ask

[jgourlay]

First time working with anything other than kingsford....so forgive the idiocy of this question, but I really don't know.

How do you tell the difference between "clinker" and unburnt coke?

[rthibeau]

Clinkers are fused debris and stuff that will "clink" when tapped with a metal fire tool like a rake and is heavier. Unburnt coke is light and will break up.

[Glenn]

Clinker (in my forge) is usually a hard heavy substance that looks like there was some glass melted in to it. Different fires product different types of clinker due to the material that was not burned.

Sand, scale, rust, and impurities in the fuel all contribute to form clinker.

[mtforge]

I had the same question when I started out and didn't have anyone to ask. So at the end of the day I let the fire sit as is and just go out. Then the next day I did a post mortem on the remains and learned what was coke, coal and clinker. In an ongoing fire, to me, the coke is rounded and the clinker is sharper/rougher looker.

[rthibeau]

Probably the most difficult thing for me to understand was the clinker thing ...the coal I use doesn't produce any clinkers unless I use flux in forge welding. After I finish a session of forging in the coal forge, I clean it out to make sure the fire is out, but there is never anything to take out such as clinkers. So, my conclusion is, I must be doing something different or I'm using some really good coal. Does everyone else always get clinkers in coal or what??

[blkbear]

As per the title of my message - there is no such thing as a dumb question. If you don't know, or understand, or perhaps there has been a question raised about your understanding of a subject. You need to have an answer to clear up your question. Maybe others don't ask because they are too shy to ask or appear foolish or perhaps they thought they knew the answer.
Whatever the reason - it doesn't matter.
From the discussion thread that your posting is starting to generate, more people will end up understanding clicker than before you asked - me included.

Brian

[yesteryearforge]

Clinker is the unburnt inpurities from the coal
It heats up and usually liquifies and trickles down thru the fire where it comes in contact with the cold air from the blower source and resolidifies to form whats known as a clinker , sometimes referred to as dragon droppings

[easilyconfused]

I usually use charcoal but when I use coal, I've noticed that when you let off the air, the clinker will generally darken faster than the coke or coal. And it looks sharper while the coke looks more like clouds.

[one_rod]

Originally Posted by rthibeau

Probably the most difficult thing for me to understand was the clinker thing ...the coal I use doesn't produce any clinkers unless I use flux in forge welding. After I finish a session of forging in the coal forge, I clean it out to make sure the fire is out, but there is never anything to take out such as clinkers. So, my conclusion is, I must be doing something different or I'm using some really good coal. Does everyone else always get clinkers in coal or what??

I forge with good quality processed coke and, like you, never get any clinker at all. In the days when you were allowed to burn coal in this country I used to get quite a bit of it.

The poor-grade anthricite that I use for heating the house produces a lot of clinker, but once it's cool it simply gets crushed up and goes out through the mechanical de-ashing system on the boiler.

So yes, a lot seems to depend on the fuel being burned.

With a bit of experience it's not that hard to spot clinker forming in the forge. It always forms in the same place, and shoving a cold steel poker through it will make it stick and pull out like so much toffee.



one_rod.

[R Funk]

Charcoal is a very acceptable fuel for forging, however I would us "lump" charcoal not briquet charcoal.

Briquet charcoal has a lot of foreign material in it. Since raw charcoal is relatively expensive they add ground limestone which is cheap and a chemical compound to improve combustibility. I am sorry I don't remember the exact compound but I knew 20 years ago and if I remember correctly it is a chemical that we don't want near hot steel. My first reaction it contains sulfur but I am not certain.

You can see the limestone, as ash, remaining after the fire is out. Sometimes I have had briquets look nearly whole after they are burnt due to the quanity of limestone ash.