Hi All,

I know there have been various discussions about scale in the past, I've had a look and they have been helpful.

My problem is with the making of ladle bowls and the buildup of scale within the bowl.  As the bowl takes shape (I hammer it into a home made former) the scale becomes harder and harder to remove by brush due to the shape of the bowl (can't get my brush in there).  In the time take to forge the bowl, the scale builds up and becomes very hard (no doubt due to hammering). I've tried vinegar as apickle but I find it relatively slow and even after a couple days hasn't always loosened up the really hard embedded scale. 

I'd rather not use anything highly toxic, or particularly dangerous to handle. An thoughts?

 

THanks!

Depending on the size and shape of the ladle you might get some success from one of those little wire wheels you put in a dril.

I've never tried it but that's probably the first thing I'd try

Would fluxing it with borax prevent or at least inhibit the scale production in the first place. hopefully preventing or reducing the problem before it begins?

Don't sink it so hot. Flux works well as a prophylactic measure to prevent oxygen contact and scale. Be aware if you do flux, hot flux is going to spray out of the bowl when you hammer it.

I sink ladles, bowls, etc. over a through hole in my swage block. A ring made of round bar, coil spring is primo, works a treat for sinking ladles, etc. There's no real need for a bottom die, "form." Sink it till it's deep enough and stop, plannish as desired.

Of course that's just me.

Frosty The Lucky.

23 minutes ago, Frosty said:

hot flux is going to spray out of the bowl when you hammer it.

Good point Sir, I was thinking flux would have been easier to clean out than scale before commencing forging, or at least the majority of it. Maybe i realy should have post posted that part of my train of thought.....DUH!

Anneal it and sink it cold which will remove most of the scale as part of the process.

Getting a crockpot and using Sparex #1 pickling compound warm

dipping in HCl

I second Frosty.  Just a further thought:

Real flux, such as borax, works not only by keeping oxygen out. It also combines with the iron oxides i.e. scales into compounds that are fluid at high temperatures. 

Maybe it is possible to flux and scrape the boron-Iron-oxygen compound out when still hot.

Polish with a tennis ball or similar such and sand paper attached to the outside, on a drill. Change size of ball as needed. Or could make a tumbler...

I used to pickle my ladles and bowls in phosphoric acid and follow up with a wire brush burnish.

I now find it more efficient to blast them (chilled steel shot or aluminium oxide for mild steel, virgin aluminium oxide for stainless steel)  to remove the oxide and again follow up with wire brush burnish.

You can buy small spigoted cup brushes which work perfectly well in the chuck of a pillar or bench drill (drill press).

Alan

Be extra careful when using aluminum oxide or virgin aluminum when scaling steel.  You do not want to form Thermite.!  See the thread Warning! Thermite.

You do not want to burn or blow up your shop or yourself!

10 hours ago, WayneCoeArtistBlacksmith.c said:

Be extra careful when using aluminum oxide or virgin aluminum when scaling steel.  You do not want to form Thermite.!  See the thread Warning! Thermite.

You do not want to burn or blow up your shop or yourself!

Thank you for the warning. I certainly don't want to blow myself up...and I don't want to form Thermite accidentally...however I think you may have mistaken the chemistry. The Aluminium Oxide abrasive powders as far as I know are very stable.

I understand Aluminium Oxide Al₂O₃ is the product of the thermite reaction and not the fuel.

I don't mean this aggressively... but do you have any evidence to the contrary? I would be very interested to see it.

Alan

MSDS-AluminiumOxideAbrasiveGrain.pdf

 

If you can't get your brush in there possibly try a soft-ish wire wool? Using white malt vinegar, try letting the bowl sit in the vinegar for 6 hours, pull it out and give it a going over with the wire wool, then put it back in the vinegar. Try repeating that process till you're happy. I have used vinegar and a wire brush to strip thick galv off field gate hinges in in 24 hours.

When I make bowls I sand them down with 120g emery cloth to bring out the texture, the highlights are just spots where all scale has been removed. If you wanted a black finish you could always do a process similar to this to remove the scale, then gently reheat the bowl in the forge back to a black heat without making new scale. I find my gas forge is 10 times worse for scale than my coke forge.

@ Joel... I assumed the OP's wish to remove the oxide was for hygene/food use rather than aesthetic reasons...but that assumption could well be more because that is what I need for my stainless steel ladles.

Nice bowls by the way.

Alan 

Cheers. They earn me some beer tokens, the folksy textured look sells. They have olive oil baked into them like cast iron skillet.

It was unintentional if I my reply sounded like I was suggesting a method for the sake of aesthetics rather than function, in my head I was just suggesting methods that works at getting scale off when you can't get a brush in there.

On the hygenic side: If a bit of scale doesn't come off after 24 hours in vinegar and a rub with wire wool, then I really doubt it's going to come off when someone puts some nibbles in there for general consumption at a party.

On the aesthetic side: the slightly scarred look of a scaley surface might put someone off from buying a bowl because it doesn't look food safe.

Hitting stubborn scale with a copper mallet can loosen/knock scale off without denting your work.