Discoloured and pitted metal

[blacksmith03]

I am a beginner blacksmith and I've been making some small projects. I keep running into the same problem which is all my projects are slightly pitted and have a dull red colour. Any ideas or solutions?

Much appreciated! 

Here's a pic

 

[arkie]

What kind of steel are you using?  What kind of forge...gas, coal, charcoal, etc.?

[ThomasPowers]

Are you aware of what scale is and how it is formed?  How about flash rusting?  How do you finish your work after it comes out of the forge?

WHERE ARE YOU AT?????????  A Saturday spent with an experienced smith should put you over 6 months ahead of trying to learn strictly on your own.  (If you are near El Paso TX or Socorro NM, USA let me know and I'd be happy to go over the basics with you.)

[blacksmith03]

I am using a gas forge and cold rolled steel. After my metal comes out of the forge, I clean it off with a wire brush then wax and quench. This is what I was taught to do when I took classes.

Did some more research and I think its gotta be scale. How should I remove it and how should I be finishing my work? 

Thanks!

[ThomasPowers]

Which gas is your gas forge burning? Propane, Methane, Hydrogen, Acetylene? I'm guessing propane. If so you usually don't get pure propane but a mix and sometimes I have noticed a red colour on the workpiece that I have assumed was an oxidation product that that particular mix was more prone to.  Power wire brushing or tumbling will remove it, (as will acid solutions---but then flash rusting can put you back near where you started...)

Anyone else have better data?

[blacksmith03]

I'm burning propane. I'm going to get a power wire brush as soon as I can. Any specific kind I need? 

[Steve Sells]

hard to say we have no idea what is available in your part of the 150+ countries served by IFI

[blacksmith03]

Ok no problem I'll research it more. Thanks

[ThomasPowers]

I use a soft wire wheel on my bench grinder, which paradoxically I never have a grindstone on and I use a twisted/knotted cup brush on my angle grinder WITH GREAT CARE AND TREPIDATION AND THE WORKPIECE FIRMLY HELD IN A VISE OR EXCESSIVE LARGE AND MASSIVE!

[blacksmith03]

Ok will do. Thanks for the info. This has been very helpful

[Irondragon Forge ClayWorks]

4 hours ago, blacksmith03 said:

This has been very helpful

Something that's helpful is this thread. I always suggest reading it. https://www.iforgeiron.com/topic/53873-read-this-first/

 

[anvil]

Make sure you clean the scale off of your anvil face.

And the red is oxidation. If you hot oil your piece at a black heat, the oxidation will be gone.

[swedefiddle]

Good Morning BS03,

Forget the power tools, use a file when the material is still hot (BLACK HEAT). Get used to working by hand, slowly. Saves on the junk pile, or, pile to be redesignated. An old Farrier File has a rasp and a file, works a treat on hot material. Planishing heat needs very light blows to 'Finish' your work piece. I would break the corners of your ends, with the hammer, before planishing and filing.

Neil

[John B]

On 10/19/2018 at 11:03 PM, ThomasPowers said:

I use a soft wire wheel on my bench grinder, which paradoxically I never have a grindstone on and I use a twisted/knotted cup brush on my angle grinder WITH GREAT CARE AND TREPIDATION AND THE WORKPIECE FIRMLY HELD IN A VISE OR EXCESSIVE LARGE AND MASSIVE!

Hi Thomas, Like yourself, I hate using the angle grinder with a wire wheel and have found a solution I am a lot more happier with.

What I am using looks the same, but in fact is a car bodyshop buffing/polishing machine. The arbor is the same as the angle grinders, but it has a variable speed control between 500 to 3000 rpm.

Still have to treat it with great respect, but not so prone to flying wires.

[Marc1]

Agreed JohnB, despite assurances to the contrary, wire wheels for angle grinders don't do well at 10,000+ rpm Their use requires full face cover and no one else around, and the little wires fly off regardless of them being twisted knotted or other meaningless gimmicks 

Like you I switched to a 6" buffer that spins at 1/3 of the speed, still does the job and does not demolish the wirewheel. Also a tad quieter. 

[Beavers]

BS03

I was having the same problem. Daswulf suggested an overnight soak in vinegar. I tried it this weekend and it worked great at removing all the scale.  I wire brushed after the vinegar and it left it nice and clean looking.

[anvil]

When using any acid, including vinegar, make sure you neutralize or it will quickly rust.

[olydemon]

I use wire wheel brushes on hex posts (like for a drill motor) in my dinky craftsman drill press. Get them at lowes/home depot. They aren't as aggressive as a wire wheel on a bench/angle grinder and I don't get any wire projectiles lodged in my clothing....

[Chris Comtois]

OP says he wire brushes, waxes, then quenches.  Would the quenching after waxing do something to the finish?  I generally wax my pieces at a black heat and just leave them to cool. 

[ausfire]

On ‎10‎/‎22‎/‎2018 at 7:10 AM, Marc1 said:

 I switched to a 6" buffer that spins at 1/3 of the speed, still does the job and does not demolish the wirewheel. Also a tad quieter. 

Marc, could you give more details about the above mentioned machine? I clean up scale with a wire wheel on a bench grinder. I am careful, but well aware of the inherent danger. More than once a ram's head bottle opener has rocketed past my ear. A 6" buffer at a lower RPM sounds like a nice option.

And I'm asking you because you are Australian, and what you can get in Sydney, I can probably get up here. In Cairns anyway. If it's a car buffing thing, then perhaps Autobarn, Supacheap or Repco? 

[Marc1]

Ozito 1100 Watt 180mm polisher ... bunnings, Mitre ten, etc cheap too.

 

https://ozito.com.au/products/spr-7100/

[ausfire]

Thanks Marc. I have a few Ozito tools and can't complain about them. Cheap, but seem to work well. So do you use some other attachment for scale removal? Sand discs would seem a bit aggressive and would leave scratch marks. Polishers would be too soft. I was thinking they may come with a flexible nylon pad like you can buy for angle grinders. So what do you use?

[blacksmith03]

Will a block wire brush take off all the scale or should I go with a power brush?

[ThomasPowers]

Yes, No, Maybe depending on the piece and the scale and how vigorous you are.

If you have to have a scale free piece and it has a convoluted surface, I go with chemical means of scale removal.

[Marc1]

I use a wire wheel screwed on to the polisher. The polisher attachments are of no use for cleaning steel. My reasoning for using the polisher instead of the Milwaukee 5" rat tail grinders I use for cutting and grinding, is that the grinder at 10,000 revs, demolishes the wire wheel and  sprays bits of wire all around me. I pulled wires from clothes, socks, and even skin. Not fun.

The polisher at 3500 does the job. As far as Ozito tools, I must clarify they are bottom of the birdcage tools, however, as with many tool manufacturers, they make a few good tools and they are the big rotary drill and the polisher. If you want a good professional tool you have Milwaukee and Dewalt and Bosch for 2 times the price. Since I don't use the wire brush that much, I decided to experiment with a cheap throw away tool and it turned out to be OK. 

For those on the other side of the Pacific, in Oz, the prices of power tools are from 2 to 3 times your prices so we sometimes need to compromise. 

PS

Another good Ozito tool is the reciprocating pruning saw. My daughter gave me one for my birthday and I had very little hope for the little thing. I thought it would be ok for a few times and then the bin. I was very wrong. It has a minuscule battery and I have used it to prune the branches off two massive trees for 3 winters. A white cedar branches 3" thick and a Mulberry tree i prune every year to avoid the Flying bats invasion. Can't kill it goes and goes. Fantastic little thing.