The 3c Combine Harvester and Oil Rig Stamp of the 1967-1973 Centennial Issue

Today's post deals with one of the least complicated values of this series: the 3c. One of the reasons for this is because after October 31, 1968, the 3c stamp saw much less use than it had before that date. From its issuance on February 8, 1967 until October 31, 1968, it was used to pay the third class rate. However, after this date, the third class rate was 5c, so the 3c stamp became a make-up stamp only. The only exception to this were the precancels, which were only available to select customers of Canada Post, and not the general public. So as a result, there are no PVA gum printings of this stamp, nor are there any major variations of tagging, except for the precancelled stamp with general Ottawa tagging, which was issued in 1972.

Along with the 2c, this value was issued in booklet form, and there were two major categories of 3c booklet stamp:

• The stamps printed by CBN and included in the OPAL booklets issued on October 26, 1970.
• The stamps included in the 25c booklets printed by BABN, issued on June 30, 1971.

Both of the booklet stamps can be easily identified by the straight edges, and the fact that the shades and overall appearance of the stamps is completely different from the sheet stamps. 

With regards to the sheet stamps, the main points of variation are the paper, which comes in several varieties of dead, dull and low fluorescence, the gum, the shades of purple and the perforation. The coil stamps show some variation in paper, gum and shade also. 

The remainder of this post will discuss the characteristics of each of the major categories of this stamp in detail.

The Untagged Sheet Stamps - Unitrade #456, 456i, 456ii, 456xx, 456xxi and 456xxii

Paper Characteristics Other Than Fluorescence

Apart from fluorescence, there was quite a range of papers used to print the sheet stamps, that differed in terms of their surface coating, appearance when viewed against back-lighting, colour and surface porosity when viewed under magnification. All of the types found are vertical wove, and mint stamps and blocks will generally curl from side to side. The different types found can be described as follows:

1. One type is a very light off-white when viewed against a stark white background. It has a very shiny printing surface, and under magnification, it is very clear that the paper has been coated with a very thin layer that gives it the characteristic sheen. The paper shows very indistinct horizontal mesh when viewed against strong back-lighting. 
2. A second type is a much more yellowish cream colour, but with the same shiny coated surface as the paper above. The paper shows distinct horizontal mesh when viewed against strong back-lighting. 
3. A third type is also a cream colour when viewed against a stark white background. It has a smooth printing surface, that is not overly shiny, because the paper is not coated on the surface.  

Paper Fluorescence

Unitrade lists dull fluorescent, non-fluorescent and low fluorescent papers. What is confusing about their listings is that none of them refer to fluorescent fibes, when the low fluorescent paper always contains fluorescent fibres. In addition, there are variations of the dull fluorescent paper that contain small amounts of fluorescent fibres as well. Finally, the dull fluorescent paper exists in a variety of different colours under UV, which can make it difficult for collectors to distinguish between the dull fluorescent and non-fluorescent paper, if one does not know what to look for. 

The first two blocks below show the difference between the non-fluorescent paper and dull fluorescent paper:

The block on the left is the non-fluorescent paper, and appears dull greyish violet under UV light. The block on the right is a dull fluorescent greyish white paper. The difference can be really quite marked, though it is not as pronounced if the dull fluorescent paper you are comparing to is violet or deep grey, as the appearance is much closer to the non-fluorescent paper, than the block shown here. 

The following picture shows an example of the dull fluorescent paper that gives a greyish appearance under 

The next block in the picture below could very easily be mistaken for non-fluorescent paper. But it is actually dull fluorescent paper that gives a deep grey appearance under UV.

The next block is another example of the dull fluorescent paper. But this time, the paper gives a violet-grey reaction under UV, and there are very few medium fluorescent fibres embedded in the paper.

There are not enough fluorescent fibres in this paper to alter the classification of this from dull fluorescent to low fluorescent however.

The next block is an example of the low fluorescent paper, as listed by Unitrade:

The actual fluorescence level of the paper is dull fluorescent violet grey. But there are very sparse concentrations of medium and high fluorescent fibres, that together, give a sparse concentration overall, and raise the perceived fluorescence level to low. If you look closely at the picture, you can see mottling in the stamps, which is the fluorescent fibres.

The next picture shows another example of non-fluorescent paper, only this time instead of being a dull greyish violet under UV light, it is grey. It is deeper though than the dull fluorescent grey, which is how I classify it as non-fluorescent.

The next picture shows another example of the dull fluorescent paper, containing a small number of fluorescent fibres in the paper:

The basic fluorescence level of this paper is dull fluorescent greyish, with very few medium and high fluorescent fibres visible in the paper. 

Finally, the picture below shows a third example of the non-fluorescent paper. This time it is the block on the right, which gives a non-fluorescent brownish grey reaction under UV light. The non-fluorescent greyish violet paper is shown for comparison by the block on the left

Thus, there are at least 9 different papers used to print the 3c sheet stamps. Most, if not all of these fluorescence levels are associated with specific paper characteristics, as discussed in the previous section. So I think the actual number of different papers that can be collected on these is 9 or 10, and not much more. 

Shades

There is quite a range of shades on this value, and Unitrade only lists two: dull purple for the basic stamp, and a red-violet shade on the tagged stamp. However, this shade also exists on the untagged stamp, as will become apparent from the first scan below. 

Here is an example of the shade that Unitrade refers to as the red-violet. It is much redder than any of the other shades of this stamp. On the Gibbons colour key, this shade is a perfect match to deep rose lilac. 

Next, we have different variations of the so-called basic dull purple shade shown in the scans below:

The block on the left is a very close match to Gibbons's deep reddish lilac, but with a little black and just a bit duller. The block on the right is more reddish, being very close to Gibbons's blackish purple.

The block on the left is the dullest of the purple shades, being closest to Gibbons's blackish lilac, but even duller. The block on the right is closest to Gibbons's deep reddish lilac, but noticeably duller. This shade is duller than the one of the block in the previous scan on the left. 

The last shade that I have found on this stamp is a slightly lighter and duller version of the blackish purple, shown below:

Under UV light, these shades do not change significantly, becoming just darker versions of themselves. Therefore I would classify the inks used to print these stamps as non-transformative. 

Gum

All of the sheet stamps, except for the general Ottawa tagged precancel were issued with dextrose gum only. However, within this category of gum are quite a large number of distinctly different types of dextrose gum. They differ in terms of colour, surface sheen, and uniformity of application. The different types can best be described as follows:

1. A yellowish cream streaky gum with a satin sheen. 
2. A smooth, yellowish cream gum with a satin sheen. 
3. A smooth, yellowish cream gum with a semi-gloss sheen.
4. A smooth, yellowish cream gum with a blotchy appearance. This gum is noticeably thicker than the other gums. It is generally associated with printings of these stamps made in 1970.
5. A smooth, yellowish cream gum with a glossy sheen. 

The gum types appear to exist with most of the different paper types and shades, and do not seem to be limited to any one type. So we can assume for now, that most paper types and shades can be found with each of the above 5 gum types, potentially. 

Perforation

This stamp is found with all four line perforations that are found on CBN stamps of this period: 11.85, 11.95, 11.85 x 11.95 and 11.95 x 11.95. 

Precancels

Unitrade lists precancels for each of the major paper types: dull, low and non-fluorescent. I do not know if they are specific to a particular paper type, gum type or shade variation. I would assume in the absence of evidence to the contrary, that all printings of this value with dextrose gum exist 

precancelled. 

Bringing it All Together

We have here at least 9 different papers, 6 shades, 5 types of gum, 4 perforations and finally normal and precancelled varieties. So there should be: 9 x 6 x 5 x 4 x 2 = 2,160 possible collectible stamps! This is, if all varieties can be found in conjunction with the others. There were 2 plates used and so there could be up to 8 x 2,160 = 17,280 different plate blocks. Of course, there probably are not quite this many, but this suggests that this stamp affords a vast amount of scope for someone up for the challenge of collecting every possible variety. Finally, there are up to 12 blank positions that can be collected, making for a possible 25,920 corner blocks. 

The Tagged Sheet Stamps - Unitrade #456p, 456pi, and 456pii

Paper Characteristics Other Than Fluorescence

The paper used for the Winnipeg tagged stamps is the generally the same as that used on the untagged stamps, with the possible exception of the uncoated paper, which appears to be associated with printings made in 1970, when the use of the tagged 3c would have fallen out of favour. There are at least two types of coated paper found on these stamps, which correspond to the types described for the untagged stamps. 

Paper Fluorescence

The levels of fluorescence found on the tagged stamps are very similar to those found on the untagged stamps, except that I have not found examples that contain fluorescent fibres. So it would appear that all of the papers used to print these stamps are variations of dull fluorescent and non-fluorescent. 

The pictures below show some of these varieties:

The block on the left is the dull fluorescent greyish white paper, while the one on the right is the non-fluorescent grey violet paper. If you look closely at the right block in the selvage on the left side, you can just make out the remnants of the tag bar that was placed in the pane immediately to the left of this block. The narrow selvage on both sides of this block indicates that it comes from one of the centre panes. The left block comes from the bottom left pane, as evidenced by the wide selvage at left, and narrow selvage at top. 

This is another block from the lower left pane. This one is printed on the dull fluorescent greyish paper. 

Shades

Unitrade lists both the dull purple and the red-violet shades, neither of which are named correctly, as our study of the shades so far has revealed. So, it would seem that the same range of shades found on the untagged stamps should exist on these as well. The only possible exception would be the deep dull rose lilac shade that was described above in the section dealing with the untagged stamps. This shade was found on an uncoated paper, with high gloss dextrose gum, and appears to be associated with one of the later printings of this stamp, made after the Winnipeg tagged stamps had been discontinued for this stamp. I know that this stamp was not available in 1970-1971, as I have seen post office packs from around this time that specifically mention the unavailability of the 3c Winnipeg tagged stamp. 

Gum

The gum types generally mirror the untagged stamps, again with the exception of those gums typically associated with the later printings, being the high gloss dextrose gum and the blotchy semi-gloss dextrose gum. The semi-gloss yellowish cream, satin yellowish cream and streaky yellowish cream gums are all found on these stamps. Again, the gum types do not seem to be associated with any particular shade or paper type. 

Tagging - Appearance and Characteristics

The tagging bars appear either a yellowish white on some stamps, and a bluish white on others. I am not 100% certain whether or not this has to do with the underlying fluorescence of the paper altering the appearance of the tagging or not. For the time being, I am assuming that there are indeed two different types of taggant used for these stamps, and that it is the chemical differences that account for the different appearance of the tagging under UV light. The yellowish white tagging is shown on the top stamp in the above picture - a stamp that is printed on a dull fluorescent brownish grey paper. The bottom stamp shows the bluish white tagging. This stamp is printed on dull fluorescent greyish paper. 

The tagging bars were 8 mm wide and generally were spaced between 14 mm and 16 mm apart on the sheets, being placed to run down the vertical perforations of each column. From partial tagging bars found on the selvage of blocks from the centre panes, we now know that each pane had its own tagging layout, and that there was only a very small amount of space between each layout, in between panes. 

The tagging bars were also not continuous down the two panes. Rather, one set of tagging bars was applied to the upper panes, which stopped in the middle of the selvage separating the upper and lower panes. Then the tagging bars applied to the lower panes started in the same selvage tabs, just below where the other tagging bars ended. Thus on blocks from the upper panes, you will see a gap in the tagging bars, in the lower selvage tabs of these blocks. In contrast, on blocks from the lower panes, the tagging bars will extend all the way through the lower selvage with no break. This can be seen in the following picture, showing a block from an upper pane, and one from a lower pane:

The left block is from an upper pane, and if you look carefully at the lower selvage tab, you can see a distinct break in the tagging. The block on the right is from the lower centre pane and shows the tagging extending all the way through the selvage. 

Finally, on the first column of some of the centre panes, the horizontal spacing between the tagging bars is narrower than on all the other columns, due to the fact that two sets of tagging bars from two different panes meet inside a very narrow piece of selvage. This narrower spacing is a full 1 mm narrower than that seen on other columns of the sheets. The picture below shows this nicely:

If you look carefully at the top block and compare it to the bottom block, you can see that the spacing between the tag bars of the left selvage and the first column is narrower than that between the first and second columns, and second and third columns. 

Finally, 1-bar tagging errors do exist on this value also, as a result of significant shifts of the tagging either to the left or the right. I just recently identified one for a customer, but did not take a scan of it. So unfortunately I cannot show an example here, but it is similar to the 2c tagging error that I showed in last week's post. 

Perforation

Like the untagged stamps, the tagged stamps can be found with all four line perforations: 11.85, 11.95, 11.95 x 11.85 and 11.85 x 11.95. 

Bringing it All Together

There are fewer paper, shade and gum varieties on these, but I think it is pretty safe to assume that there are at least three different paper types, 5 shades, 3 types of gum, 4 perforations and 2 different types of tagging. Therefore there should be: 3 x 5 x 3 x 4 x 2 = 360 collectible single stamps. There were no inscription blocks for the Winnipeg tagged stamps of course, but there are up to 12 positions that can be collected for the field stock blocks. This means that there could be up to 4,320 collectible corner blocks. 

The Precancelled General Tagged Stamp - Unitreade 456pxx

Paper Characteristics Other Than Fluorescence

For all intents and purposes, the paper used for this stamp is white in colour. Against a stark white background, it is a light off-white, but it completely lacks the yellowish tone of the earlier cream papers. Like the earlier papers, it is vertical wove. Under magnification, the printing surface is smooth, but the paper is not coated, and occasionally you can just see the odd stray fibre on the surface.  If you hold the stamp up and view it against a strong back-light, you will generally see a very fine vertical mesh running through the paper. 

Paper Fluorescence

I have generally found two very similar, but different types of low fluorescent paper on these stamps, as shown in the picture below, which makes both blocks shown appear slightly darker than they are: 

The block on the left is a dull fluorescent greyish white colour under UV, and contains a low density concentration of low fluorescent fibres. The block on the right is a dull fluorescent greyish colour under UV, and contains a low density concentration of low fluorescent fibres, and a sparse concentration of medium fluorescent fibres. In the case of the first block, these fibres make the paper appear low fluorescent greyish white overall. In the case of the second block, the fibres make the paper appear low fluorescent bluish white. 

Shades

I have only found one shade on all the stamps and blocks that I have examined so far, and it is a variation of Gibbons' deep reddish lilac. The colour shown here is a little bit duller than the Gibbons swatch. So I would call this colour deep dull reddish lilac. 

Gum

I have found two very similar types of PVA gum on these stamps. In both cases, the gum has an eggshell sheen. The only difference between them is the colour: one type is distinctly off-white, while the other is white. 

Tagging - Appearance and Characteristics

The general Ottawa tagging used on these stamps consists of 3 mm wide vertical bars that run down the perforations of the stamps in the sheet. The horizontal spacing between the tagging bars does vary slightly from exactly 21 mm on some of the outside columns, to 21.5 mm on some of the inside columns. 

All of the blocks that I have appear to be from the lower panes, given that the tagging bars terminate mid way down the bottom selvage tabs, and there are no remnants of other tagging bars at the bottom of these selvage tabs. There is no reason to believe, though, that the layout of the tagging bars on the sheets of these stamps would be any different than it was for any of the other general Ottawa taged stamps. 

The tagging in all cases glows a bright greenish yellow. Without exposure to UV light, the tagging visibility does vary. You can see this by looking at the scan of the two blocks under the heading "Shades". On the right hand block, the tagging is essentially invisible, and does not show up until exposed to UV light. The left hand block on the other hand shows pale yellow tagging being visible even without the aid of a UV lamp. 

According to Rose, this stamp does exist with the tagging shifted so as to create a 1-bar tagging error, with the band placed towards the left half of the stamp. It is quite scarce compared to the other 1-bar tagging errors that occur with the general tagging. 

Perforation

All of the stamps that I have examined with this precancel are line perf. 11.85 only, which is consistent with my general observation that stamps issued after 1971 do not exist with the 11.95 gauge, as it had been completely retired by this point. 

Bringing it All Together

For this stamp there is much, much less variation possible than the other printings examined so far. There are 2 different papers, 2 different gum types and normal and shifted tagging. That makes for only 8 collectible stamps, 96 collectible corner blocks, or 16 warning strips of 20. 

The OPAL Booklet Stamp - Unitrade 456x

Paper Characteristics Other Than Fluorescence

This is one of the few low value stamps from this series to be printed on horizontal wove paper. When  mint stamps and panes are left out, they tend to curl from top to bottom, which confirms that the paper is indeed horizontal wove. The paper is a light cream colour when viewed against a stark white background, and under magnification, it is clear that although the printing surface is very smooth, it is not coated. On the back, there is usually a very distinct vertical ribbing visible. 

Paper Fluorescence

Unitrade lists the paper fluorescence level of the OPAL booklet as hibrite. I have found that while there are indeed many examples that are hibrite, there are also examples that are closer to high fluorescent on the brightness scale. In any event, the colour under UV is a very bright bluish white. 

Shades

I have only found one shade of ink on all of the stamps that I have examined over the years. It is a perfect match to Gibbons's deep rose lilac, and is shown in the scan below:

Gum

The gum on these stamps is a deep yellowish cream dextrose gum, that is smooth and even in its application across the stamp. It has a semi-gloss sheen. 

Perforation

In the booklets that I have examined, I have found all four line perforations commonly found on the low values issued before 1971-72: line 11.85, 11.95, 11.95 x 11.85 and 11.85 x 11.95. 

Bringing it All Together

This is a relatively straightforward stamp. The only attribute that really varies is the perforation, so there should only be 4 collectible stamps of so - maybe 16 if you include all the possible edge configurations. 

The BABN Booklet Stamps - Unitrade #456a, 456ai, 456aii and 456aiii

Paper Characteristics Other Than Fluorescence

The characteristics of the papers used for BK66, BK67 and BK68, from which these stamps originate, varied quite widely, both in terms of colour, direction of weave, and appearance under magnification. 

The paper used for BK66 and BK68 is a cream coloured vertical wove paper, that shows very clear and distinct vertical ribbing on the face. The surface is often pitted by very tiny depressions, but is otherwise smooth under magnification. The surface however, is clearly uncoated, as it lacks the surface sheen normally associated with coated paper. 

The paper used for BK67, the $1 booklet, is a soft horizontal wove paper with a light cream colour, when viewed against a stark white background. The surface is often pitted by very tiny depressions, but is otherwise smooth under magnification. The surface however, is clearly uncoated, as it lacks the surface sheen normally associated with coated paper. 

Paper Fluorescence

The fluorescence of the paper on which these stamps are found varies quite widely. The stamps that come from BK67 - the $1 booklet containing the 7c, 3c and 1c, are printed on paper that gives a dull fluorescent greyish reaction under UV light, and seems to contain no fluorescent fibres at all. 

The stamps that come from BK66 and BK68 are on paper that varies from dull fluorescent to medium fluorescent according to both Unitrade and McCann. However, in reality the basic paper is dull fluorescent, with a sparse concentration of brownish woodpulp fibres AND a concentration of fluorescent fibres. It is the density, as well as the brightness of these fibres that determines whether or not the paper appears dull, low or medium fluorescent. 

Let's take a look at an example of a stamp from a booklet that would be classified as low fluorescent:

This paper contains a sparse concentration of low fluorescent fibres, and a very sparse concentration of medium fluorescent fibres. By sparse, I mean that there is a very light distribution of fibres accross the stamp, but the gaps between individual fibres could be as large as 1 mm. Very sparse means that the distribution is not even, and there could be gaps 2-3 mm with no fibres. This paper has a sparse concentration of brownish woodpulp fibres. 

Let's take a look at another low fluorescent paper:

The difference between this and the paper above is difficult to see from a picture, but this paper contains a low density concentration of brownish woodpulp fibres, and low fluorescent fibres, as well as a very sparse concentration of medium fluorescent fibres. Thus, there are more low fluorescent fibres in this paper, which would normally make it appear brighter. But, there are also more brownish woodpulp fibres, which have the effect of making the paper appear less fluorescent. So overall, this paper appears similar to the one above, even though the components that make up the paper are different. 

The following picture shows the difference, although not particularly well, between the low fluorescent and medium fluorescent papers. It is an example of BK 68, in which the top pane in the booklet is on medium fluorescent paper, and the bottom pane is on low fluorescent paper:

 

If you look carefully at the picture, you can see that the paper of the top pane is brighter under UV light than the bottom pane. The difference in reality is much more stark than it appears in the picture. This paper is a low fluorescent bluish white colour and contains almost no woodpulp fibres. But it does contain a low density concentration of low fluorescent fibres and very sparse concentrations of medium fluorescent and high fluorescent fibres. These fibres together make the paper appear to be medium fluorescent. 

The picture below shows a side by side comparison of a stamp from BK67 on the left, which is on DF paper, with one from BK66 on the right, which is on LF paper:

They do not look that much different here, in terms of brightness. But in reality, the stamp on the left looks bluish white compared to the yellowish grey of the stamp on the left. The difference in colour though of the ink shows up very clearly here, with the stamp on the left being much more of a reddish purple, than the one on the right. This should be a useful aid to identifying used single stamps. 

Shades

The dull colour of the booklet stamps is very distinct, and quite unlike anything that we typically see on the sheet stamps.

This stamp is from BK67. It is closest to deep dull purple on the Gibbons colour key, but is quite a bit darker, containing more black than the Gibbons colour does. I would say that it is actually a deep dull blackish purple. There is quite a bit more red to this colour than the stamps that come from BK66 and BK68, as will be seen from the next scan:

This colour is almost black, but with a purple undertone. The difference between this colour and the stamp above is not obvious if you focus too much on each stamp, but can be seen most easily by scrolling the images back and forth and looking at the overall stamps. Then, you should be able to see the difference very clearly. There isn't really any swatch on the Gibbons key that comes close to this colour, so I would simply call it a dull purple-black. 

Under UV light these colours appear more or less exactly as they appear in normal light. Therefore, I would consider the inks used to be non-transformative. I have seen no significant variation in the shades of ink used for these booklet stamps. 

Gum

For some strange reason Unitrade only lists the singles from BK66 and BK68, with PVA gum, and does not list those singles from BK67, which were printed with dextrose gum. The dextrose gum found on the stamps from BK67 does vary slightly from a crackly cream gum, with a very fine crack pattern, to a smooth cream gum that has the appearance of having light horizontal streaks running through it. 

The gum found on the stamps from BK66 and BK68 is a cream coloured PVA gum with a satin sheen. 

Perforation

All of these stamps are comb perforated 12.5 x 11.9.

Bringing it All Together

Again, these are fairly straightforward stamps. There are really only two varieties of the stamps from BK67, and possibly four, if you include the straight edges at left and right as separate varieties. For the stamps from BK66 and BK68, the only attribute that differs on them is the paper, and I have counted approximately 4 different types of paper (dull fluorescent, two types of low fluorescent and medium fluorescent). This makes for a total of four collectible single stamps from these booklets. 

Coil Stamp - Unitrade #466

Paper Characteristics Other Than Fluorescence

Generally speaking all of the papers that I have examined on these stamps are vertical wove papers, as evidenced by the fact that the mint stamps tend to curl from side to side, when left exposed to the air. The paper colour is a definite cream colour when viewed against a stark white background. If you examine the printing surface under a loupe, you will see that the paper is uncoated and the surface is smooth, but a few stray fibres are visible on the surface. If you hold the stamps up to a strong back-light, you can generally see a faint horizontal mesh in the paper. There is a second type of paper, which has a highly porous printing surface, which is still smooth. Although it is a vertical wove paper, there is still a distinct horizontal ribbing that is visible on the gum side of stamps printed using this paper. So far, this second paper type seems to be confined to the precancelled stamps, but it could potentially exist in combination with the other varieties. 

Paper Fluorescence

Unitrade lists two paper types for this stamp: DF and LF/fl. In reality, nearly all the coil stamps ou will come across will contain at least 1 fluorescent fibre. But where the number of fibres is very low (generally under 5), the paper will be considered DF. The LF-fl paper will contain at least a sparse overall concentration of fibres, which might consist of very sparse concentrations of several different types of fibres. But it will be enough to raise the perceived level of fluorescence from DF to LF. The general level of ambient fluorescence seen on these is usually either a dull fluorescent greyish paper, or a dull fluorescent greyish white paper under UV light. 

The picture above shows the dull fluorescent greyish paper on the right, which contains just 1 or 2 high or medium fluorescent fibres. The middle stamp is the dull fluorescent greyish paper containing very sparse concentrations of low, medium and high fluorescent fibres. If you look very carefully at the picture above, you can just see the brighter fibres in the paper. The stamp on the left is the dull fluorescent greyish white paper containing very sparse concentrations of low, medium and high fluorescent paper. Together these fibres raise the perceived fluorescence level from dull fluorescent to low fluorescent. 

Shades

I have found two very similar, but clearly different shades on the coil stamps, as shown below:

If you avoid fixating on any one part of the design and just compare the overall stamps, you will start to see that the stamp on the right is more reddish than the one on the left. The stamp on the left is closest to Gibbons's deep reddish lilac, but contains a hint of black, making the colour even deeper than the Gibbons swatch. The stamp on the right is very close to Gibbons's blackish purple, but is just a hint darker. 

Under UV light, the shades merely appear as darker versions of themselves, so the ink is classified as being non-transformative. 

Gum

On these coil stamps, I have found three distinct types of dextrose gum:

1. A smooth, yellowish cream gum with a satin sheen.
2. A smooth, yellowish cream gum with a semi-gloss sheen, and
3. A streaky yellowish cream gum with a semi-gloss sheen.

It would appear that these gum types can exist in combination with any paper type or shade, although a detailed study would be required to confirm this. 

Perforations

All of these coil stamps were line perforated 9.4. This is usually quoted in the standard stamp catalogues as 9.5 horizontally. 

Precancels

Only one precancel type is known on these coil stamps, consisting of three pairs of black vertical bars as shown below:

The total width of the precancel is exactly 15 mm. Each bar is about 0.75 mm wide, and each pair of bars is approximately 2.33 mm wide. The spacing between each pair of bars is 4 mm, so that the total distance occupied by the spacing between pairs of bars is 8 mm of the 15 mm, and the remaining 7 mm represents the combined with of the bar pairs.

Bringing it All Together

I have identified four types of paper, 2 shades, 3 types of gum and both normal and precancelled versions. So excluding the various strip varieties that can be collected, there should be: 4 x 2 x 3 x 2 = 48 collectible singles. If you expand this to include jump strips, wide spacing strips, narrow spacing strips, cutting guideline strips, start strips, end strips and repair paste-up strips, the scope expands to 48 x 7 = 336 collectible varieties. 

This concludes my examination of the 3c stamp of the series, and one of the only denominations that I can cover in a single post. As you can see, there is a surprising amount of possible scope on this stamp due to the combination of shade, paper, perforation and gum varieties that can be sought out.  Next week, I will tackle the dextrose gum sheet stamp printings of the 4c seaway lock stamp.