Ammonia, stress corrosion cracking, and 14K gold nibs

Several years ago I posed the question of whether pen cleaning solutions containing ammonia could pose a risk to gold nibs via the process known as stress corrosion cracking (SCC). The original discussion at FPN can be reviewed here (the responses on Lion & Pen contained less of substance, and in any event are now lost). The most useful scientific paper cited in that discussion was David A. Scott, "The Deterioration of Gold Alloys and Some Aspects of Their Conservation", Studies in Conservation, vol. 28, no. 4 (Nov 1983), pp. 194-203. According to Scott, gold alloys in the 9-14K range are most vulnerable to stress corrosion cracking, whereas gold of 18K purity and greater is largely invulnerable. A number of reagents that could provoke stress corrosion cracking were mentioned, including aqueous solutions of ammonia. Unfortunately, details were not provided concerning the concentration of these solutions, or the length of exposure required before embrittlement took place.

That particular online discussion ended without any firm conclusions being drawn. My concerns remained, however -- enough that I drastically cut back on my own use of ammonia solutions on gold nibs. If ammonia could embrittle gold nibs, it would be a slow, cumulative process -- very possibly taking years or even decades before becoming apparent -- so I did not find any reassurance in arguments that consisted of little more than, "I've not had any problems, so it must be OK." What worried me particularly was the large number of  vintage gold nibs with cracks in locations that just didn't make sense. Cracks where a nib is subjected to repeated bending are readily explained by metal fatigue. But what about cracks in the heel of a nib, where it is firmly sandwiched between the feed and section? Fatigue would not seem to be a concern there, so why are such cracks so common? Conventional wisdom is that the gold was made too hard, but if so, why are these nibs so often cracked only where they are wedged into the section? The answer may be that while the heel is the part of a nib least subject to the cyclic loading that causes fatigue, it is the part of a nib under the greatest constant stress. And it is that very stress that makes materials vulnerable to stress corrosion cracking.

A recent reexamination of the materials science literature available online has helped fill out this picture. The studies cited by Scott, for example, are referenced in more detail in Jennifer M. M. Dugmore and Charles D. DesForges, "Stress Corrosion in Gold Alloys", Gold Bulletin, vol. 12, no. 4 (Dec 1979), p. 141:

Much of the published work on the stress corrosion cracking [of] gold alloys is that of Graf and his co-workers and results were obtained using binary gold alloys. For example, Graf (15) found that the susceptibility of such alloys actually increases as the gold contents increase from 5 to between 15 or 20 atomic per cent, in which range maximum susceptibility is observed. The precise gold content at which the maximum susceptibility occurred depended on both the corrosive media and the stress applied to the alloy. When gold-copper alloys were exposed to a mixture of ammonia, water and oxygen the maximum susceptibility occurred at a gold content of about 15 atomic per cent . . . Graf also observed that as the gold content was increased above that at which the susceptibility to stress corrosion cracking was a maximum, the susceptibility dropped rapidly and the alloy appeared to become virtually immune. In other work (3), this author reported that ultimately the susceptibility dropped to a constant low value at higher gold contents, an effect he attributed to strong general surface attack. He also observed that when the stress was increased, not only did the susceptibility to stress corrosion cracking increase but its maximum was shifted towards higher gold contents.

It is previously explained that "9 carat alloys contain about 18 atomic per cent, and 14 carat alloys often less than 30 atomic per cent gold. In each caratage, the percentages vary according to the atomic weights and the proportions of the non-gold components present in the alloys." While this might at first glance suggest that the gold content of 14K alloys puts them comfortably above the level of maximum susceptibility to ammonia-induced stress corrosion cracking, the last sentence of the longer passage quoted above indicates that under higher stress there might be no safety margin after all.

This is at least partially confirmed by another article, W. S. Rapson, "Tarnish Resistance, Corrosion and Stress Corrosion Cracking of Gold Alloys", Gold Bulletin, vol. 29, no.2 (Jun 1996), pp 61-69, which makes specific mention of fountain pen nibs, and of ink (p. 64):

SCC may be induced not only by exposure to acids during pickling but also a result of contact with reagents such as ink, traces of hydrochloric acid in the atmosphere, perspiration, etc. It has frequently been initiated at points of stress created in annealed low carat alloys by subsequent stamping. Articles such as fountain pen nibs, rings, chains, etc, provide well-known examples.

A further reference appears on p. 66:

In early production of 14 carat fountain pen nibs, for example, Loebich (27) has stated that when ternary Au-Ag-Cu alloys were used, it was found desirable to age the fabricated nibs. In the aged condition they did not undergo stress corrosion cracking in use; whereas if heated to the point where they became homogeneous, cracking by the action of the ink became likely. When certain 14 carat quaternary Au-Ag-Cu-Zn alloys are used, however, such ageing is apparently unnecessary. This could be due to the known limiting effect of the zinc on phase separation in these alloys. The susceptibility of alloys of this type to stress corrosion is apparently considerably influenced both by their zinc contents and by heat treatment. Analogous anomalies occur in the case of the white Au-Cu-Ni-Zn alloys and these have been discussed by Graf.

I have not yet been able to consult the articles by Loebich (who worked for Degussa: Otto Loebich, "Metallkundliche Probleme bei der gewerblichen Goldverarbeitung", Zeitschrift für Metallkunde 44 (1953) p. 288-92) or Graf (L. Graf and J. Budke, "Zum Problem der Spannungskorrosion homogener Mischkristalle III: Abhangigkeit der Spannungskorrosionsempfindlichkeit von Kupfer-Gold und Silber-Gold Mischkristallen von Goldgehalt und Zusammenhang mit dem "Mischkristall-Effect"", Zeitschrift für Metallkunde 46 (1955) pp. 378-385). Nonetheless, the fact that 14K nibs did have problems with stress corrosion cracking is highly significant. While that exposure was to ink -- that is, to acids and salts -- rather than to ammonia, we now have incontrovertible evidence that under the right conditions, even very weak solutions of known problem reagents can eventually leave alloy gold fatally embrittled.

What can we conclude from this? It seems clear that the observed cracking of nibs at the heel is indeed due to stress corrosion cracking -- and on balance, it is likely that this is primarily due to long-term exposure to ink, rather than to much shorter exposures to ammonia. We cannot assume that ammonia exposure is no more damaging than  ink exposure, however, given that typical ammonia cleaning solutions are far more reactive than ordinary modern inks. And given the cumulative nature of stress corrosion, minimizing ammonia exposure is only prudent.

One precaution to be considered is to remove nibs from sections before cleaning. Stress corrosion does not take place where there is no stress, and by all indications, nibs are most stressed by being wedged into their sections -- though internal stresses cannot be entirely ignored. If nibs are removed and cleaned separately, one also has the option of using other solvents not implicated in stress corrosion at all, such as denatured alcohol.

A further question is how ammonia solutions react with gold alloys in an ultrasonic cleaner. The scrubbing action of an ultrasonic will typically remove more encrusted ink in a minute than in hours of soaking, but ultrasonics are also known to be able to erode objects by driving the cleaning solution into microscopically small surface cracks and pores. Though it would seem that ultrasonic cleaning has the potential to dramatically accelerate the process of stress corrosion, I have not been able to find any relevant studies (including with other metals and other reagents).

Two final notes: While we might worry about ammonia, chlorides are a proven danger. I have personally seen a 14K gold pen overlay spontaneously crack to pieces after a few minutes of exposure to undiluted bleach. Even in very dilute form, bleach (and even heavily chlorinated water) will rapidly embrittle gold jewelry many times thicker than a pen nib. Jewelers' websites routinely caution against wearing gold rings of 14K purity or less when using cleansers, swimming in chlorinated pools, and even handling some foodstuffs (vinegar and salt, for example). And we can also learn from the jewelers regarding another aspect of stress corrosion cracking prevention, which is heat treatment. A stress relief anneal, typically 30 minutes at 250°C, is recommended after any jewelry repair. This is consistent with Loebich, cited above -- though I wonder how many of those who currently engage in nib repair have any knowledge of this.

ADDENDUM: Worth noting is the near-total absence of heel cracks on gold dip pen nibs, which were made in much the same way as fountain pen nibs, and which in use would have been subject to very similar fatigue cycling -- but very different clamping stress, and no ink exposure.

ADDENDUM: After publication of this post I was able to participate in a project involving examination of cracked gold nibs under a scanning electron microscope which left no doubt that stress corrosion cracking was the culprit. In multiple cases we could see cracks that had developed but which were not yet visible even with the aid of a standard jeweler's loupe. In subsequent discussions I found that other materials scientists with an interest in pens had done similar work, these experts unanimously confirming the stress corrosion diagnosis.

Conway Stewart bankruptcy and liquidation

Last week it was announced that Conway Stewart was under administration, with the possibility of an imminent sale mentioned. Now it seems that if there is to be any sale, it will be of the name alone, for the physical assets of the company are up for auction, starting the day after tomorrow. In addition to the expected machinery, furniture, and the like, the catalog lists a good number of pens -- including quite a few vintage pieces, undoubtedly acquired as reference specimens.

Pelikan 100N seals

The latest addition to our fountain pen seal selection is shown above: replacement piston seals for the Pelikan 100N. Late-production 100N pens with acrylic barrels use the same seals as the Pelikan 400, but many earlier 100N barrels are slightly oversize -- 9.1-9.2mm, instead of 9.0mm. These translucent green seals are similar in shape to our translucent white and black 400 seals, but are a bit larger and a bit softer as well. They are also a good choice for Pelikan barrels which are now oversize due to reaming to remove interior roughness (or to accommodate other oversize seals on the market). For pricing, see our catalog, or contact us for details on quantity discounts.

Bender pneumatic-filler

Most pen collectors can readily recite the lineage of pneumatic-fillers (pens with sacs compressed by air pressure), from Crocker's 1901 blow-filler patent to Chilton's incorporation of a hollow plunger in the mid-1920s, and thence to Sheaffer introduction of the Touchdown system in 1949.  Few indeed, however, recognize the name of Frederick William Bender, who patented and briefly produced a plunger-operated pneumatic-filler some fifteen years before Chilton.

I confess that I would be no exception, were it not for a New Jersey pen friend's discovery of a Bender pen earlier this year. That got me digging into its story, and after managing to acquire the pen I was able to dig into the pen itself -- a story in itself.

As the pen came to me, it had been converted a long time ago to a twist-filler. The inner end of the plunger had been plugged with a piece of wood sloppily glued in place, covered with the end of a rubber sac, and then used as the mounting nipple for the inner end of the tube-sac. That sac was further secured by being tied with silk thread, with the other end attached to the section nipple in conventional style.

Once all the added bits had been carefully removed, the original metal fitting became visible. Note that there is an axial hole running all the way through this assembly, including the external filling knob in hard rubber, which screws on the other end. The inner end of the plunger tube is mushroomed over, clearly to hold the piston washer. Below is the assembly with a new rubber washer installed, and with the hard rubber tube that covers the hollow brass plunger shaft.

As found, this tube had been pushed into the pen's body until it was flush with the end of the barrel. This must have been done when the pen was converted into a twist-filler, with the tube -- luckily, left uncut -- used as a bushing. Restored, it looks like this when extended:

Filling is done just as it is with a Chilton. The plunger is extended, a finger is placed on its end to block the central vent hole, the plunger is depressed, and the finger is then released, allowing the compressed air in the barrel to escape and the flattened sac to reinflate. The pen works exactly as described in Bender's US patent 825442, issued on July 10, 1906, noting that the patent does not specify the details of the piston seal.

This was not Bender's first pen-related invention, as he had applied for patents in 1903 and 1904 which were granted in 1904 and 1905 as US patents 772204 and 784538. Both dealt with internal valve arrangements of unnecessary complexity, likely never produced. His pneumatic-filler was a much better idea, however, and on October 19, 1908, The F. William Bender Company was incorporated to manufacture the new pen. As noted in Geyer's Stationer, vol. 46, October 29, 1908, p. 22:

ARTICLES of incorporation of the F. William Bender Company have been filed with the County Clerk of Hudson County, New Jersey. The company will manufacture fountain pens, with offices at No. 47 Newark street, Hoboken. The capital is placed at $50,000, divided into 500 shares of the par value of $100. The incorporators are Frederick William and Henry Bender, of Hoboken, and Conrad Goldbecker, of No. 183 Hackensack plank road, Weehawken. F. W. Bender, for many years in the insurance business at Hoboken, is the patentee of the pen, which is to be known as the “Bender Pneumatic Filler Fountain Pen." The pen is said to possess many advantages as a self filler. The holder is partly glass, though rubber covered, and contains a rubber sack. There is a plunger at the top, with an air vent which, when pulled out and released to settle back, sends out the air and draws up the ink. The company has a factory in Hoboken, but is looking for a New York location.

A shorter mention in the American Stationer, vol. 64, November 7, 1908, p. 12, adds no details, but gives the name of the third partner as C. Goldbeck, rather than Goldbecker. As far as I can tell, no glass components can be found in our Bender pen.

How long did the Bender pen company last? It was still a going concern when the March 1910 edition of Polk's (Trow's) New York Copartnership and Corporation Directory was compiled (vol. 58,  p. 77), but it is no longer listed in the 1914 edition. Bender himself died on February 7, 1912, at the age of 59. His obituary in the New York Sun of February 8, 1912, p. 7, col. 6, appears below:

From this account and others, it is apparent that for Bender the fountain pen business was a sideline. Only in the stationery trade press was his pen venture highlighted, as in this brief death notice in Geyer's Stationer, vol. 53, April 4, 1912, p. 5: "F. W. Bender, inventor of a safety fountain pen that has had considerable export business, died recently in his home in Hoboken, N. J." Where this export business might have been, remains to be discovered. As is, I have yet to find so much as a single advertisement for Bender's pen, or any mentions beyond what has been cited above.

Bender's last pen patent, 1098469, for an adjustable feed, was issued posthumously on June 2, 1914. The application had originally been filed on August 6, 1910, but was renewed on April 14, 1914 under the name of his widow, Pauline Bender, as executrix.

New seals for Pelikan 100N, 400, 120, and 140

Although we started selling replacement seals for Pelikans some time ago, we were never entirely satisfied with them. They were larger than the originals and softer, and did not always fit securely enough onto the piston shaft -- to the point that in some cases they had to be glued in place. The first ones were also bright blue, which looked nothing like the originals when viewed through the ink window, and the later ones weren't much better, being off-white.

We decided we could do better, and now the results are in: seals just like the originals, that fit securely, and made in both clear and black -- the latter giving an accurate original appearance to Pelikan 100N pens equipped with the early black synthetic seals.

They are now listed in our catalog, and will shortly be listed on eBay as well. Resellers interested in wholesale quantities should contact us directly for pricing.

UPDATE: Most earlier Pelikan 100N pens have a barrel that is slightly larger (0.1-0.2mm) inside than the 9.0mm standard for the later, acrylic-barreled 100Ns and the 400, 120, 140, etc. For these pens, we now have oversize seals in translucent green.

Dating a Waterman instruction sheet

George Kovalenko has been trying for some time to pin down exactly when Waterman first offered pens in red hard rubber. He has managed to narrow down the likely point of introduction to somewhere between November 1906 and February 1907, as is explained on his pen history blog. So when the pen below crossed my path, the instruction sheet accompanying it caught my eye as fitting neatly into this chronology.

The pen is a smooth 0512 1/2, in a Christmas box with a gift inscription dated 1910. The instruction sheet gives much space to promoting the new "Clip-Cap", and from the way the clip is represented and from the range of materials offered, the date must be right around 1906.

This is also consistent with the listing of spare parts on the same sheet, shown below. Parts are listed as plain, chased, or mottled -- Cardinal is not mentioned. Both #3 and #7-size pens are still in the lineup, as are the desk pens (eyedroppers with long, tapered barrels, too long to be carried in a pocket).

Intriguingly, the parts list includes two models I have never seen nor heard of, oversize taper-caps in #7 and #8-size.

Printing problems with Stamps.com and an HP Deskjet

This has nothing to do with pens, but since I had no luck Googling for an answer, I thought I'd share the solution that finally worked for me. Printing from the Stamps.com software to my HP D1300-series Deskjet worked fine under Windows XP. Under Windows 7 Pro it was another story. With standard settings, using print spooling, nothing would print (the print queue would read "1" for an instant, and then back to "0", without the printer making a sound). With print spooling off, sending documents directly to the printer, none of my other applications could print, while Stamps.com printing took incredibly long -- maybe a half-hour to print an envelope, for example.

Using a reference driver wasn't an option, as HP doesn't appear to offer one for this series of printers. In the end, however, the Stamps.com tech I talked to suggested that I try printing to the built-in Microsoft XPS Document Writer -- essentially, printing to a file -- and then printing from that file. A bit of a workaround, but it does the trick.

NOTE: Default print quality for printing from the XPS Viewer is "best", so for reasonable printing speed I end up having to open up preferences each time in the printing dialog to select "fast draft" instead. I have not been able to figure out how to change the default print settings of the XPS Viewer, unfortunately.

Ups and downs

 

Some ups and downs this week, the big "down" being the loss of a pen to credit card fraud (if you are offered the BHR Duofold Deluxe with the distinctive engravings shown above, it's stolen).

A nice "up" to end the week, however, was the successful restoration of the early Moore safety shown above. The pen was bought at the Chicago pen show auction; there was a gaping crack at the front of the barrel, and another in the end knob. The latter was the result of screwing the knob onto the shaft too far, splitting it from the inside end. The knob was removed from the shaft, relaxed and reformed with heat, and the crack sealed closed. The threads were then chased and deepened so that the knob could be screwed onto the shaft without excessive outwards pressure. The crack now looks like a superficial scratch.

I'm afraid I didn't take a "before" picture of the crack at the front of the barrel. Once again, the damaged area was heat-relaxed and reformed, but here the material was very thin and not entirely round or concentric, so sleeving it was very tricky work. The thinness of the barrel mouth was probably how it ended up cracked in the first place, as a heavy-handed writer putting a lot of pressure on the nib could easily overstress the thin walls holding the nib assembly in place. Repair entailed careful internal grinding of a recess for the hard rubber sleeve, then careful shaping of the sleeve's interior profile. Once again, the crack now looks like a superficial scratch, and there is enough strength to the repaired area that the pen is once again usable, with due care.

Early Moore safeties with the short cap are rare in any form. Examples with overlays are highly desirable, but to find an overlay over mottled hard rubber is extraordinary. This is certainly the first such I've ever handled, and very well may even be the first one I've ever seen. Definitely a worthwhile restoration effort!

Yet another Edward Todd

Here is another example of the creativity of Edward Todd in its heyday. This sterling silver dip pen features pierced work, which gives the effect of a silver filigree overlay over ivory. In fact, the body of the pen is hollow from end to end, and the "ivory" is a lacquer-coated metal tube closely fitted inside.

The construction is effective, and quite convincing -- as the detail above illustrates. The Edward Todd maker's mark is clearly visible next to the "STERLING" imprint.

Don't snap that box!

One thing that I learned young about the handling of Old and Delicate Things was how to close a box with a spring-loaded latch. Press the release button down -- don't snap the box closed.

This beautiful and uncommon fitted Waterman box shows why. Snapping a box closed not only puts a lot of pressure on the latch plate, but also subjects it to the impact of the falling catch -- which itself can break from the repeated shocks. In this case, it was the latch plate that gave way. Subsequent snap closures did further damage, gouging away the leatherette and wood at the latch point.

Good old boxes are becoming harder to find, and the wooden parts of hundred-year-old boxes are typically dry and fragile. So please, hold that button down, and don't snap that box.