The Armour Archive

I know some people have mentioned various types of solutions they make to de-scale the forge scale that metal gets in the forge.

What do you use. I'd like to get away from some of the harder chemicals if I can. I know in the past people have mentioned some rather household items but would love to hear about what you have used and how it works. How tos welcome!

RPM

White vinegar. Overnight, or for an hour or so if you heat it.

And do that one outdoors, it's smelly. Seriously uses up that vinegar. Scrub the softened scale off with a wire brush.

Not sure that swimming pool acid/brick and masonry cleaner/rather dilute hydrochloric acid really qualifies as among the "harsher chemicals," particularly if you cut what you've already got in the bottle by half with more water, 1 volume acid solution into 1 volume cold water. Less activity, more control; rubber gloves. You will still be battling rusting with HCl, so immediately neutralize with strong baking soda solution set ready to hand, rinse extensively and dry quickly, then oil.

HCl+H2O isn't anywhere near as mean to handle as nitric or gawdhelpus, hydrofluoric. Those I'd put in the Harsher column.

Most white distilled is only 5% you can find stronger concentrations in the cleaner isle or through chem supply shops.
The higher concentrations also pasivate stainless.

A local auto shop may have a soda blaster. It works well enough to neutralize the piece and a bit cheaper then "food grade" baking soda.

So if I use the vinegar can I just rinse it off with water and be done with it? If I use the stronger cleaning vinegar is there anything I should be aware of?

Kon,

I might do this if the vinegar one does not do what I'd like it to.

Thanks Gents!

RPM

They recommend neutralizing it (glass cleaner with ammonia works fine), but I never had a problem just rinsing it off with hot water. Rub the surface while you do so to get the oxides off, and dry it quickly.

It can kill the grass and irritate the skin.
The 5% distilled white stings a lot less in the eyes then cider vinagar.
The MSDS is fairly straight forward.

Once the scale is gone it will start to rust INSTANTLY Be prepared to oil or wax (or paint; gild, plate,...) ASAP!

...or pop it into the forge and fire-blue it! Oops! Too much; better start again!

Yeah white vinegar is commonly available and quite effective.
I have a paint bucket with lid that I put items in overnight - but only overnight! I forgot a spaulder in there for a month once and all that was left was red vinegar.

I use hot water and a rag to clean it off afterward. Then I wirebrush/buff after it's dry, and any surface rust that appears in that 30min - 1hr comes right off.

I do it both for mill scale and for heat treating scale.

So after a night in the tub I will toss it into a hot water tub then dry them off right?

Sounds good gents, thanks!

RPM

try it on a piece of scrap first before using it on armour

I use diluted muriatic acid and scotch brite pads. You need to pull the pieces out of the bath every hour or two (depends on temperature and how thick the scale was when you started and how much time you want to spend sanding the piece later) to scrub them down to keep it from etching unevenly. Bear in mind that HCl and iron bond to make ferrochloric salt, which is the color of rust. It can make even stainless steel look rusty, so you do want to scrub that stuff off and rinse well. I use the scotch brite pads instead of a wire brush to keep from embedding anything that may rust into my spring stainless.

I like using a good scrub brush under running water to clean up after a vinegar soak. Never had anything disappear but I did get a beautiful etch on an antique adze that showed the real wrought iron with a tiny plate of HC steel forge welded to it to serve as the edge. (leant it to the local Mat Sci proff to use as an example of earlier methods.)