What are "clinkers"

[rockstar.esq]

One point not already made is that solidified clinkers will clink against a metal fire tool.  Semi-solid ones will stick to it. Clinkers are also darker than coke just after the blast is cut off.  I've heard that they don't stick to cast iron but I can't prove it with personal experience.

 

I have a bottom blast fire pot where the inlet pipe sticks proud of the bottom a couple of inches.  I've got a pipe cap with a 1" hole in the center.  Clinkers flow down the coke - hit the cap and collect below my air inlet forming a doughnut shaped clinker that doesn't interfere with my fire.  Other smiths have a clinker breaker which crushes accumulated clinkers at the bottom of the firepot.

 

Another point not already made is that clinkers mess with forge welding.  Nearly everything I've ever been told or read about forge welding said to clean out all clinkers to keep them from spoiling the welds.  It's my understanding they emit gases in the heat that serve to pollute welds.  I've also heard of practical jokers putting a penny into an unwary smiths firepot to achieve the same end.

[ThomasPowers]

Biggest problem I've had with clinkers in forge welding is that they cover up the tuyere leaving all the blast to come up through just a couple of spots still open which is basically a cutting torch rather than bringing the whole fire mass up to heat.

[Marksnagel]

I am sitting here watching the movie "Christmas Story''  for the umpteenth time as I read this post. (Multitasking). 

 

The furnace in the house smokes up, makes a horrible noise, and the father yells, "It's A CLINKER!" 

 

It just dawned on me!  :blink:  They have a coal furnace! 

 

Wow! Makes sense. I am well versed in clinkers in my forge but I never thought about the chance that clinkers could form in a coal furnace with the same air starving results. 

 

Mark <><

[Borntoolate]

Now THAT'S a clinker!!!

OH SO!   "MY CLINKER IS BIGGER THAN YOUR CLINKER" is it?     :)

[Borntoolate]

I recall Brian saying that the whole clinker thing and forge welding was BS.   He was saying something about making forge welds all day with a huge clinker building up in the forge.   Now that is what I recall.   If I am mistaken then I apologize in advance.  

 

But if I put my engineer hat on I could make some sense of that.   Maybe?    

 

If the clinker is all the waste that can no longer be burned then it must be sort of unburnable and therefore kinda inert.   Don't know that to be true but if it is then it is just an obstruction in the forge not so much a contaminant.   And if it is a contaminant why is that any different than a flux that is really just meant to keep air away from the weld area.   I think that is the main reason.   And if clinker is kinda like glass which then is also kinda like sand which I have heard can be used as a flux then why is it not helping more than hurting?    

 

But what do I know.   My forge welding is not all that great regardless!!!   :rolleyes:   

[SierraBladeAndTool]

Paper beats rock, hammer beats steel, scissor beats clinker?

[Nobody Special]

With mine, it mostly just seems block air flow and cool the fire down too much for welding.

 

Is it just me though, or do you seem to get more clinkers when you have too many fines? I keep my coal in a 55 gal drum, and there always seems to be more clinker issues at the bottom of it where all the fines go to live.

[rockstar.esq]

I don't know that I'd necessarily agree that anything not adding to the fire is inert.  It's a chemical and physical change going on and I'd imagine the differences in impurities in the coal could offer a great variety of obstacles ranging from blockin airflow to noxious vapors.