Sac replacement

Some dos and don’ts on repairing a Parker Duofold button filler.

~ rupertarzeian ~ 2 Comments

Within the circle of my pen club friends, I am known for enthusing about vintage Parker fountain pens. These are plentiful at pen shows and can represent excellent value, when compared with their modern counterparts.

One of my friends bought a vintage Parker Duofold, button filler fountain pen at a recent pen show and asked for my help to get it working and to fix a bent nib. I had completed the Writing Equipment Society’s pen repair course, only last winter. The course was great but attendees still need to practice what they have learned, preferably on their own pens to start with, to gain experience and confidence before being let loose on someone else’s pen. My friend was aware of this but still content for me to have a go.

Having seen a photograph of her pen in pieces, I hoped that it might only need a replacement sac and I suggested that she order one from The Pendragons, whereupon I would have a look at the pen at our next monthly get-together.

Prior to attending the course, I had not even known what a button-filler pen was. It has an ink sac in the barrel. Alongside the sac, is a thin metal bar with a pressure plate. One end of the bar slots into a recess underneath a button (beneath a “blind cap”). When the button is pushed, the metal bar flexes, pushing a pressure plate against the sac. This forces air out of the sac, sending a stream of bubbles to your ink bottle. Then as the button is released, the sac regains shape and draws up ink.

When we met, my friend had already done the hard part, which was to disassemble her pen – remove the barrel, (which was a screw-fit), remove the sac which had perished and also remove the button from the barrel. She had not removed the nib and feed from the section but had purchased a replacement number 17 sac. The repair then went something like this:-

Replacing a sac on a Parker button-filler fountain pen (with a screw-on barrel):

  • Examine and clean the parts; the metal bar was free of corrosion; scrape off any residue of the sac from the sac peg;
  • Straighten out the nib to re-align the tines;
  • Trim the new sac to a length to fit in the barrel;
  • Tip: if the section screws into the barrel, there is a risk that, when a new sac is attached, the sac will become twisted as the section is turned; for this reason it is best to remove the nib and feed – either by pulling them firmly, or else by soaking or washing in an ultrasonic bath, applying gentle heat from a heat gun, and then knocking them out using a hammer, a drift and a nib knock-out block. Then, fit the new sac, and insert a rod up through the section and into the sac to prevent it from twisting as you screw the section into the barrel. The nib and feed are then replaced last. However, we did not do this as the nib and feed could not easily be removed.
  • I attached the new sac to the sac peg, with shellac and then dusted it with French Chalk;
  • Once the section went in the barrel, we could feel the sac twisting. However, it was only catching at the far end and we overcame this by snipping about 5mm off the sac and re-attaching it;
  • Once the section was in place, the spring bar was carefully inserted, guiding it through the hole where the button goes. This needs to be slid in with care to avoid catching on the sac. Again, the bar was liberally dusted with French Chalk.
  • The push button was then pushed back into the barrel. The pen was ready to fill.

Happily, the pen then filled. Bubbles could be seen and heard, which is what you want. The pen wrote smoothly and all appears to be well.

Being asked to repair someone’s fountain pen is a privilege and an honour but carries risk: a bit like being asked to baptise their child, you do not want to drop it! I was grateful for the honour and relieved that the repair was a success.

I do have one Parker Duofold button filler of my own, bought at the March London Pen Show. I had not used it much but thought that it was working. But on closer examination, it would write for only two pages before drying out. It appeared that this was just the ink retained in the nib and feed and that the sac was not filling. When pressing the button, no bubbles appeared in the ink bottle. With my newfound optimism, I decided to disassemble my Parker.

Old perished sac before replacement.

The steps were very similar to repairing my friend’s pen and so I will mention only the key differences:

Knock-out block, hammer and drift.
  • I soaked the nib and section in water for several hours and then applied some gentle heat from my heat gun, before attempting to remove the barrel. As my tutor used to say, “Soaked pens come apart; unsoaked pens break.”
  • After about 5 – 10 minutes’ heat, at around 160 degrees, the barrel separated from the section and, unlike my friend’s pen, mine was a simple push-fit, not threaded.
  • The sac had indeed perished and was hard and cracked.
  • The spring bar had a bit of rust, but was still usable; I dusted it with French Chalk;
  • I soaked the section in an ultrasonic, then removed the nib and feed, using a knock-out block with a hammer and drift;
  • The new number 17 sac went on nicely, attached with shellac and then dusted with French Chalk
  • I had not been able to remove the button, from the end of the barrel. Not wishing to apply excessive force, I left it in place. However this meant that the spring bar could not be inserted through the button hole, after the section and new sac were in place. Instead the spring bar had to be placed in the barrel from the open end, taking care to have the pressure plate facing inwards, before inserting the section with sac attached.
  • The pen went back together smoothly and I was ready to fill it.
New sac attached and dusted.

Since my pen had a push-fit barrel, it was not really necessary to remove the nib and feed and insert a rod into the new sac to prevent twisting when screwing the barrel back on, but it was nice to be able to clean and inspect the nib thoroughly.

Falling at the last hurdle.

However, pride comes before a fall. In my excitement at seeing the pen fill properly, I had neglected to support the pen sufficiently, whilst pressing down on the button. Without realising, I had driven the pen down into the glass bottle and bent the soft gold nib to a right angle.

Oh no! It’s Gonzo from the Muppets!

Perhaps I was lucky, but I was able to bend the nib back into shape and do some rudimentary burnishing, using the tools available, namely a wooden McDonalds’ tea stirrer and a table mat. I got the nib back in shape with the tines aligned as best I could. The pen wrote smoothly and well.

Now that the pen fills properly, I kept track of its output and noted that it wrote for 15 pages of an A5 notebook on one fill.

There is always more to learn, even in a seemingly basic task like replacing a sac or inking your pen! This is why it is best to practice and make your mistakes on your own pens first. With the button filler I tackled my friend’s pen first but I am glad that the Gods of pen repair were aware of this and saved this humbling blunder for my own.

A little battered but not beaten.

A vintage Conway Stewart “Dinkie” 550 gets a new sac.

~ rupertarzeian ~ 14 Comments

Last week, I enjoyed a week’s holiday in the heart of the Lincolnshire Wolds, a rural landscape in the east of England. We had rented a cottage which was formerly a blacksmith’s forge, in a tiny village.

We had been advised to visit the Hemswell Antiques Centre, said to be Europe’s largest antiques centre, occupying a former bomber airbase (of which there are many in Lincolnshire). Spread over four large buildings, each with many rooms of antiques of all descriptions, particularly furniture, there was a lot to explore.

A quick google search beforehand, had indicated a few vintage fountain pens for sale, including a Conway Stewart fountain pen and pencil set, which looked tempting. Once I had tracked it down, I found it to be a “Dinkie” 550 lever filler, barely four inches long, with a matching “Conway” No. 25 mechanical pencil. The Centre sells items from around 400 vendors and, unlike at a pen show, they are not on hand to answer questions. Whether rightly or wrongly, I made a hasty decision to buy the set. (This was only one search away from being an impulse buy).

Conway Stewart “Dinkie” 550 fountain pen and No 25 pencil.

After making payment, I was able to inspect the items at more length. I am ashamed to say that, in my excitement I had looked only at the body of the pen and the nib. I had not even thought to try operating the lever. When I did so, I found that it could only be raised to about 30 degrees from the barrel. Also, the barrel could not easily be removed to see what was going on inside. I had purchased a “project.”

A friend from our pen club kindly offered to replace the sac for me, having undertaken the WES (Writing Equipment Society’s) Pen Repair course and advised me not to try doing it myself. But, as she was about to go on holiday, I decided to have a go myself. I watched a video or two and read up on the procedure. Basically, you take off the barrel, take out the old sac, fit a new one and put the barrel back on. What could possibly go wrong?

First, removing the barrel was not as easy as on a Lamy Safari. I assumed (wrongly as it turned out) that the barrel was on screw threads but glued with shellac, requiring gentle heat to soften the adhesive. I borrowed my wife’s hair dryer, with a nozzle attachment to warm the barrel slowly, where I assumed the threads and the glue would be. I paused frequently to twist and pull the barrel off, conscious of the need to apply enough force to get it off but not so much as to crack the barrel.

Once the barrel started coming away it was evident that it was not threaded, but friction fit. With a bit more warming and pulling, the barrel was off! This felt like a major milestone.

Barrel removed!

The existing sac had become hard and brittle. I tipped out the contents of the barrel, forming a sorry pile of black dust and debris. I poked inside the barrel with a tooth-pick to get out any residue.

Definitely time for a new sac.

The good news, was that the lever mechanism then moved freely, through 90 degrees and I could see the pressure bar being lowered and raised again. This looked promising. I washed the nib and feed section and cleaned up the 14k gold nib with an old toothbrush.

Dinkie nib.

I was then able to measure the diameter of the sac peg, the lower step of the section, on which the sac fits. From information I found online, I would need a size 15 sac.

I ordered the latex sac and a small bag of pure French Chalk, to dust the sac after fitting to help it slide into the barrel and stop it from sticking. The sacs came in packets of two, 8cm long and to be cut to length as required. They arrived a couple of days later, from The Pendragons Partnership. They had a slight dusting of French Chalk already but it was good to add more.

I measured that I needed the sac to be about 5cm long and so cut off the excess. I then practiced pulling it over the sac peg. This was fiddly and awkward to do by hand. I believe you are supposed to use reverse needle-nose pliers to open the sac but in the absence of these, I simply held one side the sac against the peg with my thumb nail, whilst pulling at the other side of the sac to stretch it and pull it over the peg. Several times, it jumped off. Also, the opening of the sac became ragged such that I had to trim a bit more off.

Once I had practiced this, I applied some shellac to the sac peg. I managed to get the sac on the peg, but the leading edge had rolled inwards over itself. Being unable to unpick this, I decided to roll the whole sac a bit further up the pen and then slice off the excess, back to the start of the sac peg, using a craft knife. This worked and I hoped that there had still been sufficient shellac on the peg to secure the sac. A little more wriggling of the sac had been needed, to line it up straight. I then let it sit for almost 24 hours for the shellac to set fully.

The following day, I was ready to replace the barrel. This stage was also difficult! The sac (now a little shorter than I had intended) went into the barrel easily but the barrel was a very tight fit over the sac peg. I had not wanted to glue the barrel on but it was clear that this would not be necessary. With the aid of some French Chalk for lubrication, I eventually managed to push the tiny barrel all the way home, all the time afraid that it would break under the strain. Perhaps I should have filed down the sac a little, before replacing the barrel, although this would risk puncturing it.

Once reassembled, I could at last fill the pen. I chose Waterman Serenity Blue. I decanted some into an ink miser so that I could check that the pen was filling. To my relief, the pen drew up ink nicely. When I expelled the ink again a couple of times, I found that it amounted to only about 11 drops of ink. But to be fair, this is similar to the capacity of a Sailor converter.

It was exciting to have carried out my first sac replacement and to have got this vintage pen working again. It now writes smoothly and, luckily is not a gusher.

I suspect that I made many mistakes, both in the buying and restoring process although, perhaps with some beginner’s luck, it worked out all right in the end. However, I have since enrolled for the WES Pen Repair course starting in November and look forward to finding out how it should be done.

Barrel markings