Trying to make my own stain question

[billd]

After all the discussion about Nitric and vinegar stains, I decided to try it.  I used cast iron lathe turnings. I just started this Saturday.  I added the chips to vinegar and it's been sitting there doing nothing, which I understand is normal and takes a long time. 
The nitric is where my questions comes in.  I used 69% nitric mixed 3 to 1 with water.  3/4 cups of water to 1/4 cup of acid.  I then added small amounts of cast iron. It began bubbling and within an hour all the chips were dissolved. I kept adding slowly yesterday and this morning there is a little bit of sediment in the bottom of the jar and no bubbling is happening. 

Here's my question....The mixture is a very dark brown, almost black. It's clear, not cloudy at all. Will this settle out or did I do something wrong?  I used well water right out of my sink and mixed it in a clean mason jar, left uncapped in my shed. Temperature was in the low 40's last night.

Thanks,
Bill

[rich pierce]

What I have made settles out sometimes and makes mud. Then I add water and it goes clear.  When it is saturated it seems to be close to going out of solution easily with maybe evaporation or small pH changes.  LongJohn would know.

[Kentucky Jeff]

I always age my Aqua Fortis for a couple of weeks before using it.  Also, Nitric is a photosensitive chemical and will turn color all by itself if let outside in direct sunlight.  You might have diluted the nitric a little too much but the only way to be certain is to try it out on some wood.

Don't fret the chemistry too much--if it works use it! 

[Long John]

Bill,

I am by no means an authority on nitric acid/iron stains.  However, according to my references ferric nitrate is a violet color.  The way you describe your stain it sounds like you probably have a highly concentrated ferric nitrate solution.  Since there is always some atmospheric oxygen dissolved in our water we should expect some precipitation of iron oxide, primarily ferrosoferric oxide hydrate, to the bottom of the vesssel. 

From how you described your process your solution is proably quite acidic.  Make sure that you thoroughly neutralize the stock with a fresh sodium bicarbonate solution after you have heated the stock to drive off the nitrate.  Otherwise you might find the stock slowly darkening over time.

Try the stain on a scrap of wood from your blank before using it on the stock.  Good Luck!

Best Regards,

John Cholin

Good luck

[keweenaw]

I always dilute my stock nitric acid by 1:6, there is no need to have it stronger.  If you keep adding iron you'll get to the point where it gets thick and gels.  At that point you've added too much iron and there isn't much you can do with it except throw it out.  The recipe I've used with great success is 10ml stock nitric acid, 60 ml distilled water and 3 grams cast iron chips.  At 4 g iron, you'll get a gelled mess.

Tom

[Ohioan]

I'll have to look up my notes from when I made Aqua Fortis last year.  But from the research I've done, the color varies from batch to batch.  I've not heard a good theory as to why it would change up so much. 

[Stophel]

What is "cast iron"??  what all is in it?

You need as close to pure iron as you can get.  Mild steel.  Old nails works fine.  New nails are mostly from Communist China, and who knows what is in them.

[billd]

Stophel,

http://www.ksky.ne.jp/~sumie99/ironandsteel.html

Check this link out, it goes into detail.  Iron is steel without carbon.  Cast iron is melted and formed in a mold. Steel is rolled or hammered to shape.  Cast iron cannot be bent without cracking. 

Bill

[rich pierce]

Cast iron is steel with crazy high carbon as far as I know.  That's why it is brittle and wrought iron 9no carbon) is not.

[Stophel]

Yeah, "cast iron" is not just iron.

[keweenaw]

I like cast iron chips for two reasons.  One is I have a big can of them and the cracks in them from turning them off make lots of surface area so they react quickly with the acid.  The other is one avoids the other metals that one finds in alloyed steels, some of which give different colors when dissolved in acid.  There is a very high percentage of recycled steel in most imported things like nails, etc. so it's not just virgin mild steel.  The carbon is neither here nor there.  Doesn't react with the acid, just ends up in the sludge at the bottom.

Another great use of cast iron chips is in annealing and heat treating finished parts you don't want to scale.  Bury the part in a bed  of cast iron chips in a small crucible and do your heat in that.  The carbon in the cast iron chips burns off sacrificially creating an anoxic atmosphere around your part.  I heat knife blades for hardening this way too, then grab the tang and quench quickly.  No scale to remove from the hardened blade.

Tom

[billd]

I just tried some of my Cast Iron Stain on a piece fo scrap. It came out very nice. I am very pleased with the color.  And this stain is now only 4 days old. The question I posed starting this thread about the black colored liquid.....I found out some cast iron has graphite in it. Maybe that's were the color came from??  It didn't affect the color on the wood at all.

Bill

[Mad Monk]

billd,

The cast iron probably had a high carbon content.  The stain solution is very dense so the minute particles of carbon do not quickly settle out of the liquid.

The thing about "pure" iron is that you would not want some of the alloying elements found in some forms of steel.  Any chrome in the steel will give a green cast to the stain when used on wood.

Anytime you make the ferric nitrate stain with anything less than a reagent grade of iron you will get some insoluble material suspended in the stain liquid.  I used to strain my stain solution.  At first through a single layer of tightly wooven cotton cloth to get out the larger particles.  Then through several layers of cotton fabric or even several layers of coffee filter paper.  If you use the paper in the funnel you must do it slowly.  The iron rich liquid is rather heavy and will break through the paper filters if you pour the stain solution onto it in any great depth.

If you use cotton vloth to filter do not cut the pieces larger than the funnel you are using or you loose too much stain solution to the cloth.  Do not throw away the yellow iron stained cloth.  Left it dry outside for a day or two.  It will be dyed yellow.  That cloth is then very good for putting the final polish on metal parts.  Works like a polishing cloth on metal.

When I dyed cotton fabric with the nitrate of iron to make my hunting frock the iron particles that dyed the cloth quickly wore the thin chrome plating off my sewing needles and quickly dulled the needles due to its abrasiveness.

Oh boy.  I can see the mental gears turning in this crowd on this one.

The iron dyed cloth works like a scouring rush when it comes to polishing but should only be used on metals.  But will also work on horn.

[Jim Kibler]

Guys,

Think you are making this WAY more complicated than it needs to be.  There is no need to worry about using cast iron or scouring the countryside for old barbed wire etc.  It's really quite simple.  JUST USE WHATEVER MILD STEEL YOU HAVE LAYING AROUND!  I can assure you it will be just fine.  Even low alloy (4100, 4300, 8600 series etc) steel will work fine.  How do I know?  Because I've tried it.  The concentrations of elements which in THEORY may make a greenish tint is so low that it's not significant.  Think this is one of those things that has grown to be a concern for no tangible reason.   As a side note, alloy levels in cast iron are oftentimes higher than many carbon and low alloy steels.  Just because the word "iron" is part of the name "cast iron" doesn't imply that it contains more iron or would be more suited.  I've preached about this before.  Hope I'm not wasting my time once again.

[Kentucky Jeff]

I use retired Horse Shoeing nails from my ferrier.  He gives me handfuls whenever I ask.   They are very mild steel with minimal alloy content.  Another good source is old barbed wire.  Most everyone knows a spot in the woods where a big pile of old fence wire is rolled up or where there is an ancient downed fence.   But as mentioned most any mild steel will work.  Just in small chunks....

[Dphariss]

I found an old wagon tire last year while hunting and will use some of this in the next batch. Could be mild steel I suppose.
I would not bother with cast iron.
Last batch was from what seemed to be a wrought iron rod I set up in the lathe and made chips from.
Dan