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Buying a Vintage Fountain Pen, a guide.

Buying a Vintage Fountain Pen.

When buying a vintage fountain pen a question you must ask yourself before shelling out some of your hard earned cash  is simply 'Why do I want one?'

If you are clear about the reason for your venture into the vintage pen world then, hopefully, any decisions you make will be based on your actual 'needs' rather than your 'desires', unless, of course you are in a position where you can indulge yourself at will.  If you are, then good for you.  You only live once, as they say, so why not make life complete with a delicious vintage pen!

So, why do so many, otherwise rational people, lust after a 'Parker Sterling Silver 75':


 or a Silver 'Waterman Directeur General':

or a modern 'tribute pen', the 'Parker 51 empire State Special Edition':

Well, one answer is quite obvious, they want them to look at, handle, fondle, drool over, dream about, show off, and sometimes even to write with.

One of the reasons you have for wanting a vintage fountain pen may well be that simple, they are just very, very, very, extremely splendid things!

Financial aspect

Another reason you may have for buying a pen of this type is nothing to do with its splendidness but could well justify your decision: many vintage pens do represent a sensible financial investment.  I don't know if there are any financial wizards out there who have decided that 'old pens are the future' and have sunk millions into them but I would not be surprised.  If you happen to be on good terms with an aging astronaut he may be able to put you in touch with someone who has a 'Moon Dust Pen' to let you have for a paltry £20,000 or so. 

   Constructed  in Titanium, including the nib, the pen carries a panel containing dust taken from the Moon and sintered with Gold dust.


On this planet, however, an outlay of a couple of hundred pounds or so for a carefully selected vintage pen is probably not such a bad plan, particularly as you can enjoy the pen for a few years before you cash it in.

You could, of course, already be a collector of vintage fountain pens or are desperate to start a collection.  If this is the case then you are probably beyond redemption and are going to buy some pens anyway, you need no other reason than 'I am a pen collector', collecting pens is what I will do and I'm not going to justify it to you, the wife, the bank manager or God.  If this is you then you have my admiration, and my deepest sympathy. 

Actually using a vintage pen.

The most obvious reason to consider buying a pen is, of course, to have something to write with.  Except it isn't.  The vast majority of people navigate through life without giving a pen a second, or even first, thought.  You need to write something, you pick up a pen, almost certainly a ballpoint that is laying around somewhere.   The fact that you are reading this automatically takes you out of that vast majority unless you are considering buying a fountain pen as a gift for someone else.

So, let's assume you actually do enjoy writing, if that is the case then a ballpoint is out of the question, it must be a fountain pen.  Why?, what's wrong with a nice, expensive, new ballpoint such as a Montblanc Meisterstuck Platinum coated Classique for around three hundred quid?  Absolutely nothing, apart from the fact that you wont actually get any more pleasure out of using it than you would from a Bic Crystal, about 10p., it's essentially the same thing. 

It's not easy to describe the pleasure that using a fountain pen provides but I think it is connected with effort and reward.  Even if your handwriting is not good to start with it will certainly improve with practice and this will encourage more effort.  A fountain pen, unlike a ballpoint will allow you to add 'character' to your writing which could be enhanced by the choice of ink colours available.  It is easy to change the colour of your work with a fountain pen, with a ballpoint you probably have to buy a new pen each time.  It may be beneficial to completely change your writing style to get the best from your pen. I am left handed and my natural script is abominable, so I taught myself to write in the right handed style with forward sloping letters.  This is a work in progress, my writing is still horrible compared to some but it's not as disgusting as it used to be.

Flex nib or firm nib.

Assuming that you want to actually use your vintage fountain pen, as I hope you do, the next thing is to decide whether you prefer a nib with some flex or a more rigid design.  Flexible nibs allow line width variation depending on the amount of pressure applied to the point.  Most users would automatically apply more pressure on the downstroke than an upstroke of the nib resulting in line width differences in the forming of the characters without any real conscious effort.  A good flex nib will spread its tines easily, with little pressure, but snap back together as soon as the pressure is released.  Some modern nibs do flex quite easily but don't snap back immediately as a good vintage Gold flex nib does. 

Vintage versus modern pen. 

If you favour flex then a vintage pen is the way to go but if this isn't important then why not simply buy a reasonably priced, decent quality new writing stick, sorry, pen, such as a Parker Urban or a Lamy Safari?  No reason whatsoever, these are good pens that will write well and last a fair amount of time, they are well made, well designed, and usually very simple to fill and maintain.  But, a big 'but', is the fact that an eighty year old pen was designed and manufactured almost solely for purpose i.e. writing, often for long periods of time, day after day and year after year without replacement or constant servicing.  Large commercial offices bought fountainpens in their thousands for their workers to use, they were an essential tool, not a luxury or fashion accessory, although this aspect did start to creep in earlier than most people think. 

A very odd thing about modern pens is that many models are deliberately made to be heavy when it is patently obvious that if you intend use the small muscles in your fingers to accurately manipulate a six inch long cylinder for extended periods then it should be light, very light. This strange phenomenon can only be explained in terms of marketing.  Possibly someone in the Montblanc sales research strategy team, or whatever, decided that potential Montblanc buyers would never fail to understand that 'price equals quality, quality equals strength, and strength equals weight' so off they went and told the designers to come up with a very expensive looking pen but it must be as heavy as we can reasonably make it.  The result was the abominable 'Montblanc Meisterstuck Le Petit Prince Doue Classique Fountain Pen', weighing in at 52g. and carrying a ludicrous price tag of £1055.  I cannot imagine what the weight of the 'Le Grand Prince' version might be.


Thankfully some modern pen manufacturers have not lost all sense of reason and still produce good pens at a reasonable price and weight.  The Pelikan Souverain M400, for instance is a great pen.  It sells for £190 and weighs in at 14g., nice looker to boot. A vintage fountain pen from the 1930s, say, would probably have this kind of weight.  The Parker 51, an iconic pen if ever there was one, comes in at around 20g. but most of that is probably down to the metal cap.

 The choice.

Suppose we are now in a position to know that we would like, a vintage fountain pen, flex would be nice but not essential and it shouldn't cost more than £150, ideally around £70.  We would like to use the pen on a regular basis but not carry it around as a matter of course.  It could live in the desk drawer, ready to write.  The pen should have some character but also be in a restored and tested condition.  It would be good if we could recycle and replace the pen in a year or two without incurring much of a loss, if any.  Any make can be considered but an English made pen is preferable. This Summit 125, a very typical 1940s English lever filler could be a candidate:


So, a vintage fountain pen it is then, excellent, but what, exactly, is 'vintage'?  Originating from the French 'vendage' meaning 'selling' but somehow scrunged up with 'vin' for wine the term 'vintage' implies age and quality.  The 'Cambridge English Dictionary' defines the word thus:

'Of high quality and lasting value, or showing the best and most typical characteristics of a particular type of thing, especially from the past'  

Note the 'or' linking two separate criteria, it is not an 'and'.  This definition appears to suit us perfectly in that we are not pinned down, by semantics, to a pen from a specified range of dates. In practice the three 'things' that I would look for in a vintage fountain pen are quality, condition, and age.  We could also add 'rarity' to the list, particularly if we are concerned about maintaining value. As most of us are, concerned that is, let's add that to our list of things to consider.  I think we're now ready for a list, I do love lists:

Vintage fountain pen.
Flex nib if possible but not essential.
Less than £150.
Restored and tested.
English make preferred.
High quality.
Good condition.
Some rarity if possible. 
Of course the list would be simplified considerably if we had a specific requirement not so far considered.  We may be particularly interested in a particular material, Silver, Gold filled, or Black Chased Hard rubber (BCHR).  We may also favour a certain manufacturer, year, nib type, colour etc.  A pen collector recently contacted me to ask if I knew of a Parker 51 Vacumatic, made in 1947 and having a broad or medium to broad nib.  I really like a specification but it is not as easy now as it was a short time ago to source good vintage pens.  The pen would also have to be 'correct' (more on that later), I hold this collector in high regard so the pen would have to be right on all counts.
I don't think we should rule anything out completely but perhaps our specification implies practicality so a vintage eye dropper filler may well be something to steer clear of for now.   On the subject of filling systems, many enthusiasts would freak out and become apoplectic if a cartridge filling pen was considered to be truly vintage.  They may have a point but, fortunately for us, our working definition of vintage makes no distinctions in this respect, we should also note that the first ink cartridges were produced in 1927.

Finding a vintage pen. 

The next question is 'where do I find the pen?'.  
The first port of call is likely to be eBay, which is unfortunate due to the fact that the auctions don't reflect the true value of a particular pen.  The winning bid is as much to do with 'immeasurable' factors such as the time of day, what day it happens to be, the time of year, and the integrity of the seller.  It is as much a lottery as an auction.  If no one is online as the item ends the price could reasonable but with just two interested parties the price could rocket out of control. 
Pens listed at a fixed price are more likely to reflect a pen's true worth but this is not always the case.  As we speak one seller is advertising a Parker Slimfold for £450. The Slimfold is a nice enough pen, and is seriously underrated in my opinion, but nevertheless a really good one should sell for, at most, around £60.  Presumably anyone interested in a Slimfold can find a number of decent examples at around this price, or even less and give the ludicrously expensive one a miss but the description is full of superlatives, exaggerations, and downright lies and I would not be at all surprised if it sold eventually.  It isn't even a particularly good example of a Parker Slimfold, this one is:
Many of the pens offered for 'buy it now' could be worth some consideration.  It is not uncommon for pen dealers to advertise their wares on eBay and the majority are honest and trustworthy, but, again caution is the watchword.  
An extremely common issue when buying a vintage fountain pen on eBay is that the pen just does not work at all, often due to the ink sac being degraded.  This is a real problem and could easily be avoided by the seller clearly disclosing the fact that the pen isn't in working condition.  It is not enough to say 'untested', if the lever is stuck it will have been 'tested' and found to be faullty.  An average, and reasonable, price to pay to have a pen serviced, including the ink sac repalcement, is around £25.  In many cases a 'bargain' turns out to be no such thing.
 A good seller will always list with 'returns accepted', why wouldn't you? is the question.  Avoid, like the plague, sellers who use terms like 'sold as seen' or 'description as in photos' or other such nonsense.  However, if you do buy a pen that is listed with no returns and there are clear faults that were not disclosed, and I mean faults, not wear, these are vintage items after all, then eBay will usually find in your favour in a dispute but the seller can make the whole process very unpleasant.  A typical attempt at swindling may be something like:
'Parker 51 in excellent condition. Not an expert but looks fine, see photos for description'
In the photos the pen looks very nice but on arrival you are horrified to find two large dings in the cap which were concealed in the pictures.  Nobody could have missed them and they weren't mentioned or shown in the photographs so it must be a swindle attempt, tell eBay and attempt to get your money back.
All this is, of course, a hassle and an eBay purchase always carries an element of risk.  Undisclosed faults may not be evident for some time and frequently the pen is misrepresented in terms of model, or year of production.  Unless you are quite happy to 'take a punt' with your hard earned cash on something with so many variables I'd go with a reputable dealer.
All this means, of course, that it is generally pretty meaningless to compare eBay prices with those from a reputable dealer's site.  The purchase process and after sales service that a good pen dealer with a registered business offers is far superior and easily outweighs any small saving you may make by 'taking a punt'. 
Charity shops. 
One might think that charity shops would be awash with vintage Swans, Onotos, Conklins and the like but this is definitely not the case.  I have now given up trawling the shops looking for vintage pens after hundreds of visits with no success.  I think they must be just binned when other effects are carefully folded and packed and whizzed off to Bernados or whoever. 
Antique shops.
Similarly I have had limited success at antique shops.  On the odd occasion that a pen is located the antique dealers seem to work from their own price guide book where an old item is immensely valuable irrespective of condition, quality, of rarity.  During a recent tour of the antique shops in Newark, and there are dozens, I was told twice by the owners that they don't stock old pens as they always get 'nicked'.
Antique fairs.
Antique fairs, again such as the big one in Newark, are much more productive and always worth a visit but you must be early.  Pen collectors on a mission will always be the first customers and will miss nothing.
Pen shows.
My favourite sources of vintage pens, by a mile, are pen shows such as the one in London on the weekend before the lockdown.  If you know what you are looking for you will almost certainly find it, and if you don't know when you arrive you will shortly after!  Pen people are generally just very nice people, I don't know why this should be but it just is.  There are dealers from all over the U.K. and some from elsewhere in Europe.  The pens on sale are mainly vintage but there also some small pen manufacturers showing off their new designs.
The pen collecting time dilation effect is very strong in these shows.  It is quite feasible to arrive at, say, 11.a.m., spend two hours browsing, chatting and buying the odd pen only to find that the time is now 4 p.m. It is very strange indeed.
Online pen dealer
There are now a fair number of traders in vintage fountain pens to be found online.  The vast majority of these are trustworthy and honest traders with a good knowledge of vintage pens.  The websites are of variable quality, some are easily navigable with a straightforward buying process whilst others are decidedly poor.  Where many of them fail is in the descriptions of the pens and the number and quality of photographs.  When buying online it is essential to be able to make a sound judgement based on a comprehensive description, this is something that this website pays particular attention to. 
Our listings take the form of a review with a good number of high resolution photographs and full and accurate descriptions.  This is an example, the Parker Lady is not an expensive pen but great care has been taken to ensure that the description tells the whole story.  Some of the prices asked by online traders may seem excessive, particularly when compared to eBay but when all factors are taken into account this is usually not the case.
 Let's say a dealer buys a pen for £50.  The cost of a restoration, excluding any parts that may be needed is, very conservatively speaking, £25 although this depends on the type of pen and how much work is required.  The cost of hosting and maintaining a website needs to be considered along with other hidden costs such as a Paypal or similar payment option fee and the cost of postage.  A major hidden cost is the risk incurred by the dealer with every pen he buys, and any guarantee given to the buyer. These hidden costs are are significant when dealing with vintage items.  If the pen now sells for £100 the dealer has just about broken even but actually lost money if he pays himself even the minimum wage for the time spent on the pen.  The fact is that many dealers were originally, and still are vintage fountain pen enthusiasts who take pleasure in working with old pens and an online presence offers more involvement with this fascinating hobby.  For most of us it really is a labour of love.
Negotiating a price.
If you find something that interests you ask the stallholder to tell you what he knows about the pen then give it a good inspection before asking to try it.  As you check the pen, and we'll discuss how to do that shortly, make a mental note of anything that may require explanation or may give grounds for a suggesting a price adjustment.  I have found that if dealers have enough room to work with respect to the price then they will generally move a little bit.  It is probably best not to discuss price until you are fairly sure that you would like to own the pen although some buyers prefer to work the other way round i.e. price first.  That is fine but I don't think it's really fair to the dealer and also does the buyer no favours because at this stage there is no evidence to base a negotiation on. 
A well respected and immensely knowledgeable collector/dealer I know once spent a very amusing few minutes explaining how facial expressions and gesticulations from the prospective buyer can be orchestrated to bring down the price.  This includes alternately puffing out ones cheeks and sucking in noisily through the teeth whilst slowly, and almost imperceptibly shaking the head from side to side.  The occasional sudden widening of the eyes in an expression of horror is sometimes very effective but must be used sparingly, it is the nuclear option.


Inspecting a vintage fountain pen. 

This is clearly a very important aspect of the process of buying a vintage pen.  the inspection usually takes place before purchase but it is equally important to carry out a proper inspection retrospectively if the pen has been bought online.  The only essential tool is a magnifier, usually a simple jeweller's loupe, they can be found online for a few pounds and last forever.  This could be a simple lens:
Or a more sophisticated affair with LED lights, quite handy if your eyes are a bit dodgy:
Or this contraption with lights, a neck strap, and adjustable stand/ chest support, frees up both hands if required and can be worn.
The nib.
It is of the utmost importance that this is carried out thoroughly as nib work is very expensive and the cost of a replacement nib can often represent a large chunk of the original cost of the pen.  As important as the condition of the nib itself is the question of whether it is 'correct' i.e. is it the original nib or at least the same as the original.  This applies to all the other 'exchangeable' components of a vintage pen, the cap, the feed, the clip etc.  If you are unsure then ask the seller, a curt 'of course' may be the response and this is good, very good.  You have some recourse
if this proves to be incorrect.  An 'I'm not certain' or 'I believe so' response should be treated with caution although it in no way suggests that the seller is being dishonest, quite the opposite.
Physically the nib should be straight and free of bends and cracks.  If you look at the nib end on, as if you were stabbing yourself in the eye with it, (be careful here), the tines should be vertically aligned and the tiny gap separating them should be parallel sided, not 'V' shaped.  When viewed from above the tines points should also be aligned unless the nib is an 'oblique' in which case it will be sloping from one side to the other, but it should not be 'stepped'.  Any engraving on the nib should be clear and preferably crisp although there may be a little wear.  Don't expect to find a huge blob of tipping material, this practice is a fairly new feature.  The gap between the tines should taper from the breathing hole down to the tip, where only a tiny separation should be evident.  Finally the nib should be secure and correctly fitted, it shouldn't wobble under slight pressure and not be too far in, or out, of the section.
If, as will usually be the case, you are looking at an 'exposed nib', all this is straight forward.
But a 'hooded' nib such as that found in a Parker '51' or a Waterman 'Taperite' may present an accessibility issue.
You cannot see the whole nib, such as it is, but you can, and should still check the alignment of the tines and the gap at the point. A Parker '51' nib looks like this, under the hood:
The Parker 45 uses a semi hooded arrangement but even when fully exposed there isn't much of it:
If at all possible try the pen, at a pen show the dealer will be prepared for, and expecting you to do this.  Remember the pen will have been used before and will, in all probability, taken a 'set' to suit its previous owner so a slight change of 'angle of attack' might give a better picture of how the pen writes.  Most vintage nibs will not be 'glassy smooth' writers, they never were nor should they be.  My opinion is that you should know that you are using a fountain pen and a little bit of feedback is a delight.  Some enthusiasts actively 'unsmooth' over polished nibs very slightly to regain this feel.
The width of the point can vary from extra fine to extra broad and, in addition to flexible nibs a stub nib can also offer line variation.  The nib is flattish but not as square or sharp as an italic nib. The vertical strokes are wider than the horizontal ones and a stub nib in the right hands can produce some beautiful work.
The filling system.
There are a number of 'exotic', (e.g. crescent filler),  and sometimes complex (e.g. Snorkel) systems but the majority of pens you will encounter are one of a handful of designs, the most common being:
Lever filler

A lever is fitted into the barrel of the pen which squashes the ink sac inside the barrel when lifted to around 90 degrees.  when released the sac returns to its original shape under its own elasticity and, in so doing, sucks ink into the sac.  Sheaffer first patented this system and protected their rights very rigorously so the other major manufacturers were forced to modify the system just enough to evade the band of lawyers Sheaffer employed to enforce the patent.

It is straight forward to test whether the system is working as it should but the volume of ink imbibed will vary, mainly depending upon the size of the barrel and the ink sac it can accommodate.  An important thing to check with lever filling pens is that the slot housing the lever does not bulge outwards leaving a gap between the lever and the sides of the slot.  It is also good practise to run your fingers up each side of the barrel to ensure you cannot feel any bulging around the slot.
The pen at the top of the picture is a Conway Stewart showing very slight bulging, the middle one is a cheaper contemporary pen with significant bulging and the bottom image shows the Waterman 'box lever'.  This system houses the lever in a metal box so there is no danger of this problem arising.  Waterman used this on their higher end pens, in this case a rather splendid 'olive' Waterman's 512 1/2.
Button/stud filler: 

The most common alternative to the lever, for quite a time, was the button filler.  In this case a button is housed under a blind cap at the end of the barrel which, when pressed, exerts longitudinal pressure on a filler bar causing it to bend inside the barrel and compress the sac against the inner wall.  This is a Parker Duofold button filler:

And a dismantled hard rubber Selsdon pen, another button filler:
Usually several presses are needed to fill the sac sufficiently and, depending upon the quality and condition of the components the amount of pressure needed to depress the button will vary from an easy gentle push to a Herculean, two handed effort.  If you cannot hold the pen barrel in your hand and push the button with the thumb attached to that hand then there is probably something wrong.
Squeeze bar:  

All filling systems that include an ink sac depend on some method of compressing the sac.  The simplest way to do this is to remove the barrel and squeeze the sac between your fingers.  Some early 'bulb fillers' did just that and they were very efficient and easy to use.  Maintenance was not an issue as there were no moving parts and the filling system never broke, probably because there wasn't one.  The march of progress, however, demanded some sort of mechanical system so it was an obvious step to add a 'U shaped bar around the sac so you could do exactly the same thing more efficiently.  These 'squeeze bar' fillers came in a variety of shapes and sizes from a simple bent piece of metal to the Parker 'Aerometric' system, as used in the second generation of Parker 51 pens: 

Parker are kind enough to engrave instructions, 'Press ribbed bar 4 times.' on the 'sac protector'.

Vacumatic filler: 

It is also worth mentioning the predecessor of the Parker Aerometric filling system, the Vacumatic filler.  This system, also found on the earlier Parker Vacumatic pen does not use an ink sac as such but a rubber diaphragm which is pushed inside the barrel by pressing a plunger housed behind a blind cap.  When released ink is forced into the barrel of the pen, which acts as the ink reservoir.  These tend to work, or they don't, in which case a new diaphragm is required.  It is probably a good idea, if a vacumatic isn't working, to ask the seller to install a new diaphragm. 

This isn't that awkward but you do need a special tool or two, quite cheap though, and there is a risk factor to be considered.  The end of the barrel that houses the pump can be a little fragile in some pens.  Replacement barrels can be found but a decent one might set you back around £30 so it's debatable whether it's worth the hassle.
Cartridge/converter :  

From around the early 1960s the Cartridge filler became extremely popular and is now almost ubiquitous on modern fountain pens.  I don't suppose it can be considered as a 'true' filling system as it is not an integral part of the pen, more of an 'add on'.  The ink sac is replaced by a plastic disposable cartridge pre loaded with ink, this is simply pushed into the pen section and replaced when it is empty.  The fabulous Parker 75 uses this system:

An ink converter is a device that mimics a squeeze bar type filler and pushes in to the same place as the cartridge.  There are variations on the converter which include a piston type arrangement which is operated by a simple plunger or, sometimes, a screw mechanism.  As long as the cartridge and converter fit the pen properly there isn't anything to go wrong really.  some older cartridge/converter pens do preaent a small problem in that the cartridges and/or converter are no longer in production so are quite hard to find.  The 'Slim' Sheaffer Targa models are very nice pens indeed but it is always wise to buy one with a converter fitted for this very reason.  If you are considering a vintage pen with this type of filler it is well worth checking on availability before completing the purchase.

Examine the cap of a candidate pen very carefully.  First of all make sure that the cap is complete with the correct clip and end stud (often referred to as a 'jewel').   This is a Parker 'Consort' Gold filled cap from a Parker 61:


As caps from the same, or very similar models are interchangeable there is often an issue with respect to 'correctness' of the cap.  Even if it is the right cap for the particular model it could be from a pen from the wrong year, country of manufacture, or variation.  Parker 51 caps are notorious for turning up in the wrong place, English caps on American pens or vice versa, caps from apparently random years, caps with the wrong clip or caps made from the wrong material for the model.  As an example, a pen with a rolled Silver cap only belongs on an English made pen, they were never made in America.  If a '51' is Burgundy in colour it should have an English cap if the colour is definitely 'reddish' and an American cap if the colour could be described as brown.
Having ascertained that the cap is, indeed, the correct one for the pen, and it fits properly, it is time to take out the loupe and check its condition.  Metal caps should be completely free of 'dings', a ding being a dint in the metal.  Unfortunately it is common practice to attempt to conceal a ding under the clip so be sure to check here carefully.  A metal cap will almost always show some light surface scratching and this is acceptable up to a point.  If the metal cap is plated or filled with Gold or Silver check that this is not worn away in patches or worn evenly to such an extent that it looks more like a Gold wash.  It is also well worth mentioning that, in the case of Gold plated caps what looks very much like wear, particularly around the rim of the cap, is often, in fact, nothing more than a water mark that will wipe away with a jeweller's cloth.  
There is also the point that, if you want a very good pen to write with, which, after all, is what they were designed to do, and you are on a tight budget,  then, as long as the cap fits properly you could do a lot worse than a Parker '51', or '61', with a dinged cap.  Possibly the best value for a vintage writer is an early Parker 51 aerometric in black with a 'dinged' cap.  It is probably not worth buying a pen like this if you intend to replace the cap as there is a good chance that the replacement cap will cost more than the pen.
Plastic caps should be properly colour matched to the pen although in certain older pens barrel discolouration is very common, the Parker Duofold in Jade being one such pen.  Probably the biggest issue with plastic caps is the presence of hairline cracks in the cap lip.  This is very common in some models, the Parker Slimfold for example, and is rarely mentioned in eBay listings.  These cracks cannot be economically repaired and if you end up with pen with an undisclosed cracked cap lip from eBay then send it back.  It is worth getting into the habit of running a finger nail around the rim of the cap lip, if there is a crack you will feel it although you might well not see it, even using the loupe.  The number of turns needed to secure a cap, assuming it is a screw fit, varies quite a bit but if it is less than half a turn then the threads are probably damaged or worn, again not at all easy to fix.
Although, clearly, a poor cap will not affect the performance of the pen directly it's function is more than mere decoration.  It protects the nib, protects your clothes and fingers, usually gives a method of anchoring the pen and helps prevent the nib from drying out.  The clip also stops the pen from rolling about on the desk.  From the aesthetic point of view the cap is probably the most noticed feature and therefore, if the appearance of a pen is important to you, as I'm sure it is, then the cap should be in good condition.  If the cap on the candidate pen is cracked, chipped, distorted, or has damaged threads then the best advice is to look elsewhere.
  Barrel and section: 

An important technique to embed into the inspection of a vintage pen is to run your fingers up and down the barrel to feel for lumps and distortions, particularly in lever filling pens.  If the barrel can be easily removed, as in a cartridge filling pen, then run a finger nail around the open end to check for cracks.  It is a good idea to look end on into the section, again as if you are about to stab yourself in the eye, and check for cracks here.  As with the caps, walk away from cracked barrels or sections.  The one thing that tends to produce apoplexy in pen collectors is finding a section that has been scrunged by pliers wielded by a would be pen restorer, if this is the case you may have to recontour the section or buy a new one, I'd walk away.

Most pens have some sort of barrel imprint identifying the model and maker, although on some pens, the Parker 51 and 61 spring to mind, the imprint may be very small and positioned around the end of the barrel.  Some pens have no barrel imprint at all, in this case the makers name, or logo, is often to be found on the clip.  Ideally a barrel imprint should be crisp and clear although, obviously if a pen has been well used for a number of decades this will not be the case.  The condition of the imprint should be reflected in the price of a pen. 
When viewed through a loupe you are likely to see microscratches on the surface of the barrel and this is to be expected in an old pen.  Depending on the 'rules of restoration' (more on that later) that a particular restorer adopts these scratches may have been removed already.  If they haven't, and you would like your pen to look as new as it can look then it is not a difficult task to remove small scratches yourself.  Deep scratches are to be avoided as removing these without filling, a tedious task, will spoil the contour of the barrel.
Some materials have particular chemistry which can affect the surface of the pen.  Older pens made from hard rubber, or Vulcanite as it is sometimes called tend to turn from black to brown over a few decades.  This is because the material contains some Sulphur which oxidises on the surface of the pen giving a chocolate brown colour.  It is quite common to find an old pen that has been left for some time with the cap in place, the part of the barrel that has been exposed to the air is brown while that under the barrel is black as coal.  This brown layer is formed from the original surface of the pen and so removing it using abrasives is effectively removing the surface of the pen.  Most restorers don't do this but who is to judge?  If you want your vintage Conway Stewart, originally with a beautiful chased black hard rubber surface to now have a beautiful shiny, smooth black rubber surface with no imprint then that is your choice, it will no longer be the pen it started out as and will have lost a good deal of value but you will have the pen you want and that's fine by me.
Hard rubber doesn't react well with water, soaking such a pen should be out of the question.  Another material that is even more hydrophobic is Casein, used by Burnham for example.  It allows some vibrant and striking colours and patterns but it is milk protein after all.  Many, many years ago when I was a total ignoramus when it comes to pens I decided to clean my nice Burnham pen by soaking it overnight.  the next morning when I eagerly went to add the finishing touches to my 'restoration' I found a very sad looking, soft stick of stuff that bore no resemblance to the pen that I popped into the water just a few hours ago.  You aren't likely to find anything like that on sale but you could well find a casein pen with a 'crazed' surface, if this is the case, walk away, it is more than the surface that is damaged.

All this sounds fairly straight forward, you know what to look for in your ideal vintage fountain pen, all you have to do is check everything then make a decision.  Sadly that is not always the case and there will be some compromises to be made. 

Let's imagine that you are particularly fond of Mabie Todd pens, particularly the Swan brand and you come across a 1940s Mabie Todd 3320 in Midnight Blue in an antique shop. 
Mabie Todd Swan fountain pen.
You know what to check and you even have mnemonic in your head to remind you of what you need to look for.  The dealer is asking £95 for the pen, which sounds a bit steep to you but you really like the pen and it 'ticks most of the boxes', as they say.  You really wanted a flexible nib and the dealer tells you that the Swan number 3 nib is fully flexible.  You fill the pen, the filler works o.k., and you try it out on some rubbish paper that he antique dealer has on hand.  The results aren't that impressive.  To get the nib to flex you would have to apply more pressure than you would risk so, sensibly, don't push it but write normally with a touch extra pressure on the downstrokes.  There is a little line variation but not much so you decide that this particular nib, nice as it is, is semi flexible at most.  So, do we compromise and go ahead with only a slight amount of flex or do we look elsewhere?, we decide to compromise.
The pen is a good colour with clear imprints on the centre of the barrel, the feed, the section, and the barrel end.  The gold fill is in good, not immaculate, condition and the pen looks very smart indeed.  There are no cracks or deep scratches but, under magnification light surface 'microscratches' are present on the body of the pen.  You decide you are o.k. with these, perhaps you'll polish them out at some stage.  You also decide that the gold filling on the clip and cap rings is fine, a slight compromise here.  Examining the nib section through the loupe you notice there are some light 'grooves', not sharp scratches here but the imprint is crisp and clear.
Swan Pen
Perhaps the section has been marked slightly and someone has removed scratches, but not completely.  another compromise, but one that you're happy to make.
You decide to buy the pen but tell the dealer you'll just go outside for a moment to think about it.  As soon as you leave the shop you whip out your phone and Google 'Mabie todd Swan 3320' to check prices.  You are surprised to find there are very few for sale, must be less common than you thought.  There's one on eBay for £75 but it is quite badly marked and offered 'buy it now' with no returns.  There is an identical pen on a dealers website at £125  and you find another on eBay at £169, good luck with that.  So, £95 looks o.k. but a few quid off would be nice.
You return to the shop and ask the dealer what he is prepared to accept, he sucks in noisily through his teeth ( must have read this article) and says the very best he can do, and he would be making nothing, is £85.  You don't believe him but think it's a good deal so you pay the man and walk out of the shop the proud owner of a Vintage  Mabie Todd Swan 3320 fountain pen, mission accomplished.
I didn't make this pen up, by the way.  I sold it last year for £85 and the owner is very pleased with his pen, it was his first, but not last vintage fountain pen.  If you're interested you can see a review of the Swan pen here.
But is it Vintage?  
At the beginning of this article the criteria for describing a pen as vintage:
 'Of high quality and lasting value, or showing the best and most typical characteristics of a particular type of thing, especially from the past'  
now let's see if our Swan passed the test:  The Swan pen is certainly of high quality, of that there is no doubt.
                                                                     All the indications are that the pen has lasting value, it will probably increase.
                                                                     It shows some of the best and most typical characteristics of a 1940s fountain pen.
                                                                     At well over 70 years old it is certainly 'from the past'.
So the answer to the question 'Is it a vintage fountain pen?' is a resounding 'Yes'.  Congratulations, you have acquired a fountain pen that is truly vintage and meets most of your personal requirements.  Take care of your pen, cherish it, and please, please, write with it.