Pen Mechanisms Revealed – 1. The Swan Visofils

Laurence Oldfield

Introduction

The Swan Visofil pens (Fig.1) were introduced in the mid1930’s to give Mabie Todd an edge in the highly competitive market for striking ‘high-tech’ pens with ink visibility and large capacity. However, the production of these pens appears to have terminated in September 1940 when the Harlesden factory was destroyed in the Blitz. As the Visofils were on the market for only a short time they are now quite scarce.

Two different mechanisms were used for filling; the pens with the transparent filler button were known as the ‘V’ series (or Mk 1), and the pens with the extendable button as the ‘VT’ series (or Mk 2). The dates of the relevant patents and advertisements (Figs.2,3) confirm that the ‘V’ series was indeed the Mk 1.

No repair manual or drawings of the mechanisms appear to exist, so it is not surprising that there is little general understanding of how the pens work, or of how they may be repaired. I hope this article will widen the knowledge and appreciation of these important pens, and that it will lead to many of them being returned to active use.

Visofil Mk 1 – components and method of repair

The idea for the Mk 1 Visofil was patented in 1934 by Edward Sears and Mabie Todd and Company Limited (Fig.2) as an ‘ink visible pen with increased ink capacity’. The pen as actually produced differs only in detail from the patent, as can be seen from the parts (Fig.4): its operation is elegant and a natural development from pre-existing designs. The transparent hexagonal ink reservoir is an extension of the rubber sac and acts as a push button to compress the sac longitudinally against the action of a surrounding spring. The filler is prevented from rotating by a hexagonally bored brass bush fixed to the end of the barrel. This also provides attachment for the blind cap.

The Mk 1 is dismantled by removing the section (a little soaking and /or heat may be necessary), and then by pushing the filler down through the barrel. After cleaning the barrel and removing all traces of the old sac, the filler is reassembled using a 1.25 inch length of rubber sac (Figs.4,5). This should be attached with shellac to the section at one end, and to the plastic reservoir at the other; it will be necessary to hold the spring in compression while this is done (masking tape will do).

The pen is filled by the depression and release of the filler until no more air can be expelled. The top of the breather tube extends well into the clear reservoir, so the pen will fill to this level. It will contain some 1.6ml of ink (a modern converter holds about 0.75ml). The Visofil Mk 1 therefore lives up to the claims in the patent.

In view of the efficient operation and excellent performance of the Mk 1, it is unfortunate that it did not enjoy a longer production run. Doubtless, it was the impact made by the Parker Vacumatic that led to the development of a new Visofil based on what was considered to be more advanced principles.

Visofil Mk 2 – components and method of repair

The idea for the Mk 2 Visofil was patented by Mabie Todd and Company Limited, Leslie Johnson and Edward Sears in 1936 (Fig.6). The patent claims ‘an ink visible sacless pen with rapid filling (no small parts to lose) and greatest ink capacity’. It is similar to the Parker Vacumatic in that the ink is sucked through the ink channel into the pen barrel by the extension and release of a rubber diaphragm. However, the Visofil differs from the Vacumatic in several respects:

·	the diaphragm is attached at the centre of the barrel rather than at the end.

·	the button return-spring is inside the filler.

·	a square section plunger-rod acting through a square aperture prevents rotation of the filler.

·	there is no blind cap – the button being extendable on a high pitched thread to the position required for filling.

It is questionable whether the Visofil represents any significant improvement over the Vacumatic. The fact that ink could come into contact with the spring cannot be good, but the extendable button is certainly more elegant than the easily lost blind cap.

The production Visofil Mk 2 (Fig.8) shows significant differences in detail to the design shown in the patent. The mechanism is NOT removed by separation of the two parts of the barrel (these are usually cemented together). A hard rubber nut secures the mechanism in the pen and enables the diaphragm to be drawn against its seat.

A special tool (Fig.9) is required to unscrew the nut to enable the mechanism to be pulled out of the end of the barrel. This is the most difficult part of the repair as the application of reasonable heat is rarely sufficient to release the bush. Assuming that a replacement bush can be made, the old one can be drilled or turned out following removal of the plunger button. After releasing the diaphragm-retaining ring and clearing any debris from the old filler, the condition of the return spring needs to be assessed. If the spring is broken it does not have to be replaced for proper filling – it just means that filling will be a two-handed operation. Replacement of the spring requires removal of the plunger nose, but be warned, it is likely to break off, and then it will need to be reattached (hard rubber studding recommended). The new diaphragm (use a Parker ply-glass sac if available as this will ensure much longer life) needs to make an airtight seal to the angled seating where the two parts of the barrel are joined, so thorough cleaning of the inside of the barrel is necessary. The filler assembly is shown in Fig.10. This must be inserted into the pen with the button extended and pushed in against the spring. This will enable the nut to be tightened without rotation of the filler assembly against its seat.

How well do they work?

My experience with these pens has been a delight. The nibs (handmade by Swan) are soft and responsive, typically more like a Waterman than a Parker, and what a joy to find a pen that holds a good quantity of ink! My preference is for the Mk 1. It is easy to repair and the ink level is clear. Also, it does not suffer from the lack of thermal insulation that is often a problem with pens that contain their ink directly in the barrel – have you ever held an eyedropper, a De La Rue piston filler or a Parker Vacumatic in a hot hand for a while?!!

Happy hunting for the Swan Visofils, they are worth the effort of restoration.
Please contact the author if you wish to purchase the VT tool or you would like the restoration done for you.

References

Evolution of Mabie Todd pens, WES Journal, vol.12, p9, 1985
Mabie Todd, Part 2, WES Journal, vol.19, p30, 1987
Mabie Todd, Part 3, WES Journal, vol. 21, p13,14
UK Patent No. 451,275, October 1934
UK Patent No. 480,965, September 1936

Acknowledgement

I am indebted to Steve Hull for his helpful comments and for finding the patents and the advertisements.