Jump to content
I Forge Iron

Is it called slag?


metalworker77

Recommended Posts

I notice a black outer layer that forms on the objects when I heat them to a high temperature. Is it just steel? or can it be impurities in the steel such as zinc rising to the surface? like slag? It's a black outer scale that has a bit of a waxy look to it. I ask this because I kind of like it, and it doesn't seem to rust the same way as steel? it find it gives the pieces a more natural look.

Link to comment
Share on other sites

It's called scale and on modern steels is basically an iron oxide with a bit of the alloying elements thrown in. Scale may not rust at first but it will tend to flake off with temperature changes or impact and so doesn not make a good base for a protective coating. It can be removed mechanically, thermally or chemically---soaking overnight in vinegar will usually allow you to scrub it off---then rinse/neutralize the vinegar on the steel.

Or if you are using a coal fire with a dirty or green coal it can be a coating of coal tar and impurities.

If you are using real wrought iron it will be a glassy coating of the iron silicates and the iron oxide

If you have zinc *IN* your steel something is *WRONG*! (save as miniscule ammounts as a tramp element) If your steel is galvanized/zinc coated then please read the first entries on the link removed at the request of anvilfire about the death of a friend due to putting zinc coated steel in his forge.

Thomas

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...