Blue Dobell and Grey Dobell - Why Does It Matter on a Ten Dollar Note?

Seasoned collectors often use terms that bamboozle the rest of us - "Blue Dobell" and "Grey Dobell" are two bits of insider lingo that polymer note collectors use to classify different types of Australia's first blue ten dollar polymer notes.

These terms are used to describe the appearance of the standing portrait of Dame Mary Gilmour that is to left of centre on the front of our first blue ten dollar polymer notes. That portrait was painted by Sir William Dobell, which explains the informal nickname granted by Mick Vort-Ronald back in 1999. 

These terms are necessary because Australia's first blue ten dollar notes were printed to last when they first entered circulation. I believe the staff at Note Printing Australia (NPA) were so keen to ensure the notes remained in circulation for as long as possible it can be said they erred on the side of caution and look to have used too much intaglio ink in the printing process. 

If you happen to have a few of those notes set aside, compare them to some printed just a few years later and you should see a clear difference between them. Here are a few points worth observing:

- The large number 10 printed in the top right corner of both sides can often be visible (in reverse) from the other side;
- The section in the lower left of the note showing the bullocks and dray is an intense blue;
- The lines used in the standing portrait of Dame Mary Gilmour by Sir William Dobell are thick and deep;
- The main portrait of Dame Mary Gilmour shows her to have something like a deep-blue suntan;
The most extreme "Blue Dobell" notes even show the outline of Banjo Paterson from the other side of the note.

My First Problem - Transfers and Self-Soiling

The different appearance of the early notes were so great in the eyes of some in the general public, they took them to their local police station thinking they may have been forgeries. Advice from the NSW State Police indicated the notes were genuine: "They are slightly brighter ... and during the lengthy storage, part of the image of one note became faintly transferred into the next note." 

The official response from NPA was a little more detailed: "Microscopic examination showed that the blue background tinge of these notes was the result of intaglio ink wear. On the basis of this limited examination we have concluded that the intaglio ink on some of the '93 series $10 notes is wearing in a way which is leading to "self-soiling" of the remainder of the note."

I don't presume to have more knowledge of Australia's circulating currency notes than the staff of NPA but I have seen many thousands of these notes in mint condition over the years. Many collectors and members of the general public kept some of the first notes as a memento of the occasion, so they are reasonably readily available for study.

While I can see some transfer of intaglio ink from the front of one note to the back of another (and vice versa), I don't see how so much ink can be transferred on Uncirculated notes that have been carefully stored for several decades.

Instead, I believe many ten dollar notes printed during 1993 had such deep or thick intaglio ink I believe it's possible to see sections of the intaglio design through the substrate from the other side of the note!

My Second Problem - From Blue to Grey

Explanations to date for the change in appearance of the ten dollar notes printed from part-way through 1994 have focused on the colour of the intaglio ink used.

One keen student of Australia's banknotes who looked into the issue at the time was the well-known dealer Judy Shaw. Judy contacted NPA and was advised "...the variation was as a result of an attempt to rectify the self inking problem which had shown up after the initial issue of the 1993 $10 polymer notes. Later the change was confirmed but, sadly, I was informed also that no official records were kept."

I believe there is more to the explanation for the difference. While there may have been a minor change in ink colour, I believe there was also a change in the amount or type of ink applied. When I compare the fine lines of intaglio of the two types, I can see much more "spread" of the ink described as blue and more space between the fine lines of the notes classed as grey (as well as the difference in colour).

Looking at a number of 1993-dated 10 dollar notes with a magnifier, I've seen that some very clear self-inking is evident - mainly as tiny raised dots of intaglio in in sections of blank substrate.

That doesn't explain all of the reverse imagery being seen from the front of the note though. As an example, the zero in the "10" seen in reverse on the left of the front of the note doesn't have that appearance, so to my mind has a different cause.

The ghosted image of the number is visible in the bare substrate between the printed intaglio lines under magnification. This almost has the appearance of having been applied with a pale watercolour ink, and I believe can be explained by the sheer depth or intensity of the ink coming through from the other side of the note.

By contrast, the "Grey Dobell" notes:
 - Do not show a shadow image in reverse of the number 10 from the other side of the note;
 - The portrait of Sir Francis Dobell and the section showing the bullocks and dray exhibit fine "grey" lines".
 
While most members of the general public would not have noticed much less cared about these minor differences, experienced collectors know the slight refinements that NPA staff made to the production process for these notes (whether those changes were in ink colour, application or quantity) were fundamental to ensuring the notes remained in circulation for an extended period.

In the Absence of Official Records, Numismatic Detective Work Will Reveal What and When

The enquiries made by Judy Shaw indicated that "... no official records were kept..." explaining the changes that were made, nor when those changes were tested or implemented as part of the manufacturing process.

Having studied coins and notes for several decades now, I find that answer from NPA to be rather unsatisfying. I am yet to encounter a test production run of an Australian numismatic item where every single paramenter was not recorded and accounted for, with full knowledge of when those tests started and finished. 

The Melbourne Mint's testing of different die steel led to the incredible rarity of our 1930 penny; the Reserve Bank of Australia used the DBP one dollar notes to test a different type of paper in 1976; the Bicentennial $10 notes were a major field test in 1988 and test notes were released on our polymer $100 notes in 1996 as well as on our polymer $5 notes in 1997. In each of those tests, mintage figures; serial prefixes and serial numbers were all known. Some of the information about the rarity of these items came from collectors studying the physical items, and not from the organisations that manufactured them.

I fully expect all of this information was recorded for any testing that NPA conducted with different inks throughout 1993 and 1994. It may not be known yet, but when it does it could well show that some of the different types of note are quite rare and valuable.

Judy Shaw has concluded that "...the colour changes occurred randomly, and there is no specific numbering or sequence to differentiate between blue Dobell and grey Dobell notes." While that may be correct, I believe it's more accurate to say the changes were made to notes with specific prefixes and serial numbers, its just that we collectors haven't yet worked out which ones they are yet.

How Will We Work Out When the Tests Were Conducted and When the Changes Were Made?

How might the different test runs be identified? We know that there were 3 different plates used to print the 1993-dated 10 dollar notes - AA93 to DF93; DG93 to GL93 and GM93 to KE93. 

Slightly more than 40 million notes were printed from each plate, which left NPA staff plenty of room to deploy different inks across certain serial number ranges across some of those sheets.

Once the test run/s have been narrowed down to specific sheets by serial prefixes and numbers, I believe UNC examples of those notes will be in strong demand with collectors interested in obtaining a representative example of an important change to our circulating currency.