Adding Hcl To Prevent Sediment Formation In Iron-Gall Inks

[Cal_D]

So I am sitting here with a couple bottles of ink, and was thinking to myself, "Old Government recipes added hydrochloric acid to their inks to prevent sediment, but I don't smell a trace of HCl on any of these inks." HCl is hydrogen chloride gas dissolved (and fully dissociated) in water, so when the ink is used, the gas will come out of solution when the ink evaporates and leave, not affecting the Ph of the paper. As most paper is sized with CaCo3 anyway, it might react and neutralize in any situation. In any case, the amount is low. The recipes call for 2 ml pre litre. As a concentration is not given, I am going to assume that it is concentrated HCl, to play on the worst case scenario. Two ml of conc HCl is .0275 moles of HCl, which in a litre of water will provide a ph of 1.6, which not bad. The worst case one is the indian recipe, which calls for 5 ml of conc HCl. This gave a Ph of 1.15 or so. Nasty, around the same as stomach acid. My guess is that this will be the final ph of the resulting ink as well, as the tannic and gallic acids should not be full dissociated, and the increase of H+ from the HCl will shift them to be more dissolved then dissociated. This Ph seems a bit low, and might be harsh on fountain pens. Adding less or weaker acid might help with this. The iron in solution should help protect stainless steel nibs, and the HCl should not attack stainless or iridium anyway. Plastics are hit an miss, but should be fine. Off gassing might cause corrosion in if they have unprotected steel in the cap or whatever.
Now, the main point of all this is, do you think it is worth the risk adding acid to modern IG inks to reduce sediment formation? To get the effect needed, a single drop of conc HCl is all that is needed per 100 ml. (A drop on average is between .1 and .2 ml) Any thoughts? I have liters of conc HCl around, but I dont feel like frying a pen if someone knows something I dont. I am pretty sure the indian version of the ink will give small bubbles if you put it on a carbonate. Thats strong stuff. Might not even need a biocide, as not many bacteria can live in a Ph of 1, but they exist, and the PH would select for them so I guess you probably would. If sediment has formed, then adding a drop or two of HCl might save an otherwise dying ink.

[Pickwick]

Surely inks are formulated at the time of manufacture. My question is why would anyone want to additional chemicals? The only way ink will show signs of any deterioration is if it's kept over a very prolonged period of time. Those government recipes were made up at the time of manufacture, and the ink would have been used up at a fast rate.

 

With modern inks the formulation has changed, and should not require any additional additives beyond the manufacturers specifications.

 

Personally I don't think it is worth the risk, given the ink is made safe for use in fountain pens in the first place.

 

Another question arises, how long do you expect to keep your inks?

[kwzi]

If you will add hydrochloric acid than you will be able to keep ink for longer time without risk of of developing sediment - if well stored than we are probably referring to several decades.

 

Amounts of hydrochloric acid used in old formulas gives concentrations that are not easily smelled - other components of ink have usually stronger smell.

 

Be advised that hydrochloric acid alone will corrode stainless steel, this might not be very fast but it is going to occur. Presence of iron salts is going to speed the whole process significantly. So I would advise using this ink in pens with solid gold nib or at least gold plated.

[Cal_D]

I think the problem with trying to predict corrosion. is that we really don't know what "Stainless" means in regards to nibs. It might be 304 or 316 stainless, in which I would expect it to hold up to conc HCl for years. But they are not great "Making stuff out of steels" But I find it less likely that it is a spring stainless, like 440b or 420HC. Those I would expect to break down and corrode under normal use. Gold of course would laugh off just about everything unless one was driven by the odd want to run hot moist bromine through the pen. (Bromine has a nice color, I wonder if there is an ink the replicates it.) Or aqua regia.

The goal is simply to increase the lifetime of inks. We have all seen how the milder inks are storing worse. Cases of SITB are up, and people talk about using several bottles to separate out their ink to avoid contamination. Our inks must be pretty weak and pathetic if we need to do that, right? Manufactures are pulling their muscle inks, and replacing them with weaker, sadder versions of their previous selves. Looking at you, Mont Blanc. I am looking to see what it takes to bring back Rambo into my inks. A little phenol, a bit of HCL and maybe my ink will have some hair on its chest again. Be able to fill from the bottle without fear. None of these things were ever in concentration high enough to be harmful to human health, it was simple a culture of fear and regulation that removed them.

 

In regards to your question "How long do you expect to keep your inks?" How about 10 years. Just a random number. Why not? The basic chemistry is simple, and there is no reason that an ink should not last that long and be perfectly usable, assuming it was kept away from oxygen. Now, I don't think a bottle of ink around me will last that long, but that has more to do with the chemistry of caffeine and the human nervous system then the stability of iron tannate complexes.

[kwzi]

I think the problem with trying to predict corrosion. is that we really don't know what "Stainless" means in regards to nibs. It might be 304 or 316 stainless, in which I would expect it to hold up to conc HCl for years. But they are not great "Making stuff out of steels" But I find it less likely that it is a spring stainless, like 440b or 420HC. Those I would expect to break down and corrode under normal use.

 

Hydrochloric acid will attack and remove the passive layer from stainless steel of 3xx series regardless of concentration - this is just a matter of time when it will happen. Of course in case of diluted systems this is not going to look like dissolution of nib, but rather a lot of crevice and pitting corrosion will happen. But still 1 liter of standard government ink with addition of 2 ml of hydrochloric acid will be able to dissolve something about 2 g grams of stainless steel of 3xx series - actual mass loss of the nib could be somewhat higher because corrosion would proceed through space between grains and so significant amount of material could simply fall off.

And I'm afraid that most "premium stainless steel" used in fountain pen nibs in some cases should not be even named stainless - if steel looks nice and shiny this does not mean that this is already stainless steel, and also not only composition matters but also processing conditions. On the other hand certain manufacturers might use high performance stainless steel though.

 

The goal is simply to increase the lifetime of inks. We have all seen how the milder inks are storing worse. Cases of SITB are up, and people talk about using several bottles to separate out their ink to avoid contamination. Our inks must be pretty weak and pathetic if we need to do that, right? Manufactures are pulling their muscle inks, and replacing them with weaker, sadder versions of their previous selves. Looking at you, Mont Blanc. I am looking to see what it takes to bring back Rambo into my inks. A little phenol, a bit of HCL and maybe my ink will have some hair on its chest again. Be able to fill from the bottle without fear.

 

I think that was the idea when I started to make inks on my own

 

 

 

None of these things were ever in concentration high enough to be harmful to human health, it was simple a culture of fear and regulation that removed them.

 

You can't fight with it anymore - would you buy ink if there would be warning that is toxic or irritating? So producers stick to very mild stabilizers and low concentrations so they would not have to add warning notices on their products.

[Sasha Royale]

Putting acid into my fountain pen ? No ! Commercial fountain pen inks are safe for my fountain pens. I don't have good reason change the ink chemistry.

[graystranger]

Chlorine is insidious and leads to severe corrosion in almost any alloys, INCLUDING GOLD ALLOYS. Only pure 24 K gold will resist it. I damaged a 14 K gold ring by using bleach to clean out the gunk that had built up inside the ring around the stone. It embrittled the gold bezel to the point where the stone could be gently pushed out of the top of the ring. The gold was brittle and lost all its ductility. A jeweler had to replace the gold in the bezel with new gold. Google chlorine and gold. Recommended my many that you do not wear any gold or silver jewelry when you go swimming in a chlorinated pool.

 

All ferrous alloys (including all stainless alloys) are subject to corrosion from chlorine. Ferrous chloride forms on the surface of the metal when exposed to chlorine. If the metal is dry, the ferrous chloride attracts moisture from the air (it is deliquescent and will wet itself) making the salt on the surface wet. It removes the passive layer of stainless steels. With the surface wetted, oxygen will readily penetrate the chloride and oxidation of the iron in the alloy is actually enhanced. The chloride is not consumed when this happens, it becomes the oxygen transport mechanism and runaway oxidation ensues. Pinhole corrosion results. It will also attack aluminum alloys and virtually all alloys.

 

I WOULD NEVER USE ANY THING CONTAINING CHLORINE IN ANY PART OF A FOUNTAIN PEN EXCEPT PLASTIC, RESIN, OR RUBBER PARTS. Never expose a nib to chlorine.

 

Do some on-line searches. I had a project with Reynolds Aluminum's Research Center. We had materials developed for use in their aluminum casting process. I was told that no materials containing chlorine would be allowed in their foundry. Period. Others I have known from the iron and steel industry told me that chlorine containing materials were not allowed in the steel mills.

 

At any rate, chlorine is very damaging to anything but 24 K gold and maybe pure platinum alloys. Just because you do not see any problems after a few days or a week does not mean the corrosion has not started on the microscopic level. It may only show up as a nib that becomes brittle and later a tine breaks. Too many crevices in and around the nib and other metal parts of pens to be safe with chlorine in the ink.

[Cal_D]

Not much chlorine in the solution though, none really, its all in the form of chloride. You would need a strong oxidising agent to get chlorine from HCl. Something stronger then chlorine to persuade that hydrogen to take it's electron from somewhere else. Its the H+ that you have to worry about attacking your nib. In a swimming pool, there is free chlorine, and that is free to attack gold, and is capable of it. The chlorine in HCl is in the same form as seawater. Hydrochloric acid will have no free chlorine present. Bleach does. (I have seen people run that through their pens to get rid of BSB. Nasty)


You raise a good point about the the other alloying elements in the nib though. Most likely it is silver or at worst copper, all which are more stable then H+, and will be noble in respect to it. Tin might very well be present though, which can be oxidised by the acid, causing problems depending on the alloy. All iron alloys will, and the rate will depend on the degree of passivation due to their allowing elements. A stainless steel with lots of nickel I would expect to last much longer then a plain carbon steel. Any reaction with a voltage potential higher then 2H+ going to H2 gas will not react, (without something helping it, like extra voltage (which may be supplied by secondary surface reactions)) while anything with a more negative potential will.


I have a Jinhao nib that I screwed up trying to grind a while back. I can leave it in a strong HCl solution over the weekend. Some 10 or 12 molar stuff, Ill leave it under the hood. Coworkers will understand. It will be over three years worth of damage, neglecting surface reactions. Wish I had a gold nib to try it with though. At least one I was willing to risk.


Your mileage may vary.

[graystranger]

I am not talking about Cl gas or free Cl, the problem is with the Cl- ion in solution, not free chlorine. You do not need to remove Cl from HCl, it dissociates into H+ and Cl- ions in water and it is the Cl- ions that do the damage. And, they do not have to be highly concentrated as they form FERRIC CHLORIDE ON THE METAL SURFACE of any iron or steel, and this provides the oxygen transport to the iron that feeds oxidation. The chloride that forms is not consumed in the corrosion.

 

Look at seawater damage to metals. It takes longer but seawater water will damage stainless steel. I've seen photos of a stainless steel pistol that was taken out of the ocean after several years. It was eaten up with about 20 % of the metal gone.

 

This effect comes from HCl, sodium chloride, and sodium hypochlorite (bleach). THEY ALL DO THIS. Bleach releases oxygen so it may be the worst, but trust me. Talk to a metallurgist or any corrosion expert. HCl will eat up stainless steel. DuPont stores HCl gas in steel cylinders but it is anhydrous HCl gas. Hydrated HCl is never stored in any metal containers, it is stored in plastic or glass.

 

Not sure about the mechanism of chlorine attacking gold alloys, but it certainly embrittles them badly with no signs of corrosion at all in the alloy. Probably penetrates the grain structure, attacking the phases in the alloy. Gold alloys have copper, silver, nickel, and probably other metals depending on the alloy and the color of gold desired.

 

Please put another Jinhao nib into salt water, common table salt, and leave it for a week.

[kwzi]

@graystranger

Although corrosion in presence of chloride ions is problematic, they are not wash and go and certainly do need all metals and alloys.

Gold and it's alloys are completely safe and sound in presence of chloride ions (it is even suggested to clean gold jewelery in solutions of either seawater or kitchen salt with ammonia).

With the bleach, sodium chloride in them is only by product of reactive compounds in them, particularly sodium hypochlorite and chlorine, both of them are very powerful oxidizers and are able to oxidize many different compounds, including most of metals. So yes bleach can cause damage to large number of metal alloys, including some gold alloys (not all 14K or even 10K gold alloys will be prone to be damaged by chlorine or sodium hypochlorite though).

 

In summary NOCl and Cl₂ are highly corrosive for most metals and their alloys. Chloride salts with general formula of MCl_x (x vary from 1 to 4) are corrosive toward many metals and alloys, including many stainless steels, but if and when corrosion will happen depends on the concentration of salt, access to oxygen, temperature, imperfections of surface and many other factors. Some stainless steels will corrode just in seawater while other... while other will be unmoved by their presence In case of hydrochloric acid, if metal or alloy was susceptible for corrosion chloride salts, than the corrosion is also going to occur in presence of hydrochloric acid, usually it is going to be a little faster.

 

You can also read about pitting corrosion and crevice here (particularly of stainless steel): http://cdn.intechopen.com/pdfs-wm/33625.pdf

 

@Cal_D if you immerse whole nib in solution of hydrochloric acid than it might be hard to tell if there was corrosion or not because it should be "eaten" more or less on whole surface - leave some part of the nib not immersed. But for best comparison to live conditions - make a solution of hydrochloric acid, iron sulphate, put a drop on the nib, leave it for a night or day and see what happens

[Cal_D]

My plan was to suspend it by the breather hole, so part of it would be unexposed. While Cl- can chew up some alloys, it will have a hard time with high chrome alloys and good stainless steel in the short term. Every time you touch the nib you are covering it with chloride ions. The issue with stainless steel, like I said above, is that the term is meaningless. In industry, there is a tendency to separate stainless steel into "stainless" and "stain-less", with the latter being carbon based steel with a nickel and chromium content. The latter are used to make blades, cutting tools, and more then likely firearm parts, as they can be hardened. Both stainless and stain-less (carbon) steels can be attacked by acid, but the degree depends on the thickness of the chromium oxide layer which passivated it. Hexavalent chromium is tough stuff, and it takes a lot to break through it, even more so if the nib if coated in a layer of pure chrome. Imperfections not withstanding, it will laugh off chloride, moisture, and oxygen for a long long time. Our killers here are both oxidisers, like has been maintained in the form of sodium hypochlorate, and chlorine. They have to be meaner then that hexavalent chromium layer to break it down, or else have a positive reaction pathway by reducing the hexavalent chrome. If the nib was a normal steel, or it has very low to total absence of oxygen then there are some complex reaction pathways involving the iron micas that can occur. Not likely to occur in a fountain pen. If we are going to try and predict failure of a nib, then we need to know what kind of metal it is.

Nibs are tempered, which tells me they have carbon in them. They will crack, rather then bending, which implies more carbon, and quite hard. Maybe rockwell 57 or higher. They claim to be stainless, and do seem quite corrosion resistant, which would be one of the lower stainless alloys. Since nib steel is not a discussed topic among pen users, the manufacture has no reason to use a nice, high end steel, nor one that has a complex tempering procedure. So we are looking at a cheap, low end carbon stainless that is simple to use, machine and temper. My money is on 440a or a 41xx in the US, and a AUS type in japan. 440a will laugh off saltwater for a good long time, a strong oxidizer or acid through, will quickly attack it. 316 or 316l might also work, depending on hard nibs really are. There are a ton of variables here, and a lot of diffrent options. My guess is that they use whatever is cheapest at the time that works with their machines. Thats what I would do.

 

Anyways, the real risk to nibs if from H+ ions produced by the added acid. Chloride is not a major player in the reactions we will see, at least in the first order. H+ might take Fe to Fe++, which then reacts with free chloride to make FeCl2. But any acid will do the same, with the anion changing.