[Gary Mulkey]

I have always had a problem with what I believe to be excessive scale on my forged blades. Not only does this require a good bit of grinding but keeps me from forging as close to final shape as I would like. Typically what I will do once I have a blade forged to shape is to brush off as much scale as possible (while at forging temp) and sticking the blade in a bucket of lime to cool. What more (or differently) can I do to eliminate more of the scale from forming? Is it the lime that is my problem?

I would appreciate any insight or techniques that will help.

Thanks,
Gary

[Lin Rhea]

Gary,
Are you running your forge slighty gas rich? (you need to), this might help a little. Also, you may have heard of forging at reducing heats. The technique of using finishing blows works well with that method. When you get the majority of the forging and metal moving done you might turn down the forge a little and finalize you shaping at a color shade lower in temperature. Then turn down the heat a little more for your straightening stage, just a low red heat. Also use light taps for your finishing blows to smooth the surface and refine the finish. Dont be tempted to do any substantial forging at this low heat. I routinely use this technique. It takes a while to cover the entire surface, lightly heating and applying these light fast blows, but it will clean and smooth the surface. You'll have to wipe the loose scale off the top of the anvil often. For kicks, take it to a wire wheel and see how it shines when you work through the last thin layer of scale.

[Gary Mulkey]

Thanks Lin. That makes perfect sense. I am running the forge gas rich but have been forging pretty hot.

Gary

[Kevin R. Cashen]

Lin Rhea, on 12 December 2011 - 08:24 PM, said:

Gary,
Are you running your forge slighty gas rich? (you need to), this might help a little. Also, you may have heard of forging at reducing heats. The technique of using finishing blows works well with that method. When you get the majority of the forging and metal moving done you might turn down the forge a little and finalize you shaping at a color shade lower in temperature. Then turn down the heat a little more for your straightening stage, just a low red heat. Also use light taps for your finishing blows to smooth the surface and refine the finish. Dont be tempted to do any substantial forging at this low heat. I routinely use this technique. It takes a while to cover the entire surface, lightly heating and applying these light fast blows, but it will clean and smooth the surface. You'll have to wipe the loose scale off the top of the anvil often. For kicks, take it to a wire wheel and see how it shines when you work through the last thin layer of scale.

Very good tips Lin, I use the lower finishing heats myself to cleanup and keep from dinging the work all up. Ken Mankle gave me the best name for this when he told me that he called it "hammer polishing".

Also, when all done,and before you go to the grinder, soak the blade for a few hours in a strong sodium bisulfate solution. Don Fogg has recommended it for years, it is the chemical industry uses to strip scale when pickling and you can buy the crystals anywhere they sell pool or hot tub Ph supplies. It it will eat through any scale and leave you with a clean gray blade that is much easier on belts.

[ABS Webmaster]

Thank you Kevin! I am actually in Home Depot at the moment and checked the ABS Forum on my IPHONE and saw your post. Sally located a bottle of sodium bisulfate in the store in the pool supply aisle. I will use it on my next forged blade.

[Gabriel Ables]

Does anyone use water on the anvil and hammer during the low heat "hammer polishing" to bust off scale?

[Lin Rhea]

I sometimes use water but only at forging heat. Water is just on the hammer or the anvil or both. The blade just barely contacts it steaming it away immediately which is why the scale pops off. I dont use water on low heats because the water might over run the low heat on the thin edges. That may not be a big worry, but it's where I draw the line. From there I use finishing blows at a low red heat. That is a blacksmithing technique from days gone by before wire brushes.

[Bill Kirkes]

Lin, I've heard something about about vinegar for removing scale. If this true, how do you use it and when? Thanks-Bill

[Lin Rhea]

I believe thats talking about softening the forge scale before grinding.

[Mike Barton]

I have a container full of white vinegar that I use, and it removes over 90% of the forge scale before I put the blade to the grinder.

[Jeremy Lindley]

Yup, white vinegar in a container after the forging is done. Before I had access to a grinder, I was draw filing and I learned quickly that scale is REALLY hard on a file... I just leave the blade in the vinegar for a while then wipe and wash the goop off. Saves on belts, too.

Jeremy

[Lonnie Crabill]

Kevin Do you have to dip the blade in ammonia or baking soda to kill the bisodium sulfate after the scale is gone?
Thanks Lonnie Crabill