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Identifying OCP v FCP

 
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lozlinna
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Joined: 05 Nov 2008
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PostPosted: Mon May 18, 2009 10:05 am    Post subject: Identifying OCP v FCP Reply with quote

Hi there

Can anyone explain how to identify the difference between these two papers on mint single stamps (no selvedge) under short wave UV lamp. I've read Deegam, and even looked at stamps with both types of paper side by side, but to me there is no discernable difference.

Since I can't work this out I haven't even tried the more modern paper differentiation.

Perhaps I should just leave it all alone - try explaining to toddlers why daddy is in a darkened room with bits of paper - and stick to commercial use.

Thanks
Laurence
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brandenburg5
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PostPosted: Tue May 19, 2009 1:23 am    Post subject: Reply with quote

Laurence,

Try the method I describe in the third illustration here, where you put the stamps one above another and hide the area of the phosphor bands. This method allows me to see the papers clearly.

Let me know if it works for you.

--Larry
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Gooner
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Joined: 25 May 2007
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PostPosted: Tue Dec 07, 2010 7:01 pm    Post subject: Reply with quote

Bumping this as it has got lost in the amount of posts.

I am with Laurence in being unable to find out how to differentiate FCP from OCP. I also am no wiser after reading Deegam Chapter 5.

Larry's answer whilst excellent for the ATN papers doesn't actually answer the question about how to differentiate between FCP and OCP (although I assume the methodology can be adapted for this if you have the necessary "control" stamps).

I have two 7p Scotland Missing Phosphors (so no bands). One is definitely different from the other.


The single under SW UV is similar in colour to the national 19p and the pair is nearer the 26p (very rough comparisons just to demonstrate the difference in shade).

Obviously I would be very interested if I could prove one of these was FCP as Missing Phosphor is unknown on this paper.

However to even start the study I need to understand the difference between OCP and FCP without having a control issue of either.

Now I know this is likely to be a phosphorescence difference i.e. the single is probably low OBA for example, but I would really like to put to bed the idea I might have a FCP Missing Phosphor.
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Alex
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Joined: 02 Sep 2007
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PostPosted: Tue Dec 07, 2010 8:28 pm    Post subject: Reply with quote

To assure myself that I could still identify OCP from FCP I looked at the types from 2.5p magenta (XS29 & XS30). I placed XS29 (S14) & XS30 (S14Eg) side by side and held a SW UV lamp close above both. The OCP white border gives a duller white cw the brighter white FCP border. If you look at the Queen's head to the right of the CB in both the difference is quite clear. The OCP is dull cw the brighter FCP stamp. Another way to identify these apart is if they have different gums. GA is shiny and has a cracked appearance while PVA is duller (creamy) and mottled. PVAD can have coloured tinges as well. Shine the UV light across and you can see this quite distinctly.

The 7.5p is a different problem. The single on the left looks like the missing phosphor example I have as the shades look similar, whereas the pair are distinctly darker. XS47a only comes from Cy6 Ph10, and the FCP example (XS 48 - Cy6 Ph11) is not listed in QE2 Vol4 Pt 2 as existing with phosphor missing; so the variation cannot be explained by different Cy shades.

Perhaps other members can provide an explanation?

Alex.
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Gooner
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Joined: 25 May 2007
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PostPosted: Tue Dec 07, 2010 10:58 pm    Post subject: Reply with quote

Alex wrote:
The single on the left looks like the missing phosphor example I have as the shades look similar, whereas the pair are distinctly darker.

Thanks Alex - well you have given me two out of three answers.

  1. Identifying OCP v FCP - I'll have a look at my similar issues.
  2. The single is the norm for missing phosphor so that one is unlikely to be anything other than the listed variety (shame - I thought that was the odd one!!)
  3. Now can anyone else tell me why the pair is so different?

I am certainly losing the idea that either of them are FCP (they are definitely missing phosphor) as I have now checked with MCC, Connoisseur and Deegam and none list such a variety. If it existed I doubt all four would have missed it.

Sidebar - there are apparently two types of the OCP stamp though - "hi-set" and "low-set" values which aren't listed by any of the major catalogues. The low-set being the rarer of the two.
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Alex
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PostPosted: Wed Dec 08, 2010 9:57 pm    Post subject: Reply with quote

Dave,

Have a look at :

http://www.machin-and-wilding-stamps.co.uk/index1.html

for 'low' and 'high' value tablet varieties of the 7.5p.

Alex
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Gooner
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PostPosted: Wed Dec 08, 2010 10:35 pm    Post subject: Reply with quote

That's where I found it Alex - one of the best Machin reference sites but a bit on the expensive side to purchase from, but then again he does seem to have stock available of some of the harder to find issues if you are not prepared to wait and find them at a better price.
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crazyh1
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Joined: 20 Nov 2010
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Location: Lincolnshire, UK

PostPosted: Sun Dec 12, 2010 11:17 pm    Post subject: Reply with quote

Hi guys,

a couple of years ago I started to think I was losing belief that I was accurately picking out the OCP from the FCP and so asked the question of Douglas M. I have copied his reply below as it does, I think, add a little more consistency into the assessment. I do still think though, that there is an issue if the item you are looking at has spent more then the average time sitting in sunlight or is otherwise a little grubbier; in either case the comparison is that much harder. Doug's key comment is that there is actually a continuous scale of papers from the very dull to the very bright under UV and as such you are probably best off collecting from nearer the extremes of the spectrum.

Anyway, this was Doug's response.....

"Re OCP and FCP. I assume you have read what is stated on page C5-3 et seq, especially what Aubrey Walker said about there being no exact specification for it and that it is, therefore, a continuous range.
Also his remark that it is OBA in the coating and not in the paper itself that one is looking for. The best approach is to have some benchmark specimens and to keep them away from daylight. While one can choose stamps that exist only with one or the other, I myself use complete panes with margins, such as DP1 for OCP and DP40 for FCP.
Even better are prestige books with panes on the appropriate paper and large unprinted margins as these usually have large unprinted parts.
For example the British Rail book has DP87 and the whole of this pane, stamps and stub, is FCP. Even better, a complete book is unlikely to have had the panes exposed to daylight for very long and has thus avoided UV contamination of the OBA. Similarly, all the panes in the pre-decimal Stamps for Cooks book are on OCP. If a known OCP and FCP pane are laid over each other with an overlap and if an unknown stamp is then laid across them at right angles and the whole irradiated with a UV lamp (long wave will do and it is less harmful), it should be fairly easy to determine which paper the stamp was printed on. Bear in mind that an OCP stamp may have been exposed to daylight or prolonged UV and been converted thereby to FCP."

Hope that helps (it did for me!)
Scott
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Gooner
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PostPosted: Sun Dec 12, 2010 11:50 pm    Post subject: Reply with quote

Scott - that is brilliant - EXACTLY what I was looking for.

Thank you.

I think I will "sticky" this one so that it is available to see at all times.
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Alex
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PostPosted: Sun Dec 19, 2010 5:44 pm    Post subject: Reply with quote

Dave,

How do these compare with the images above;

http://cgi.ebay.co.uk/Scotland-7-p-MISSING-PHOSPHOR-corner-block-6-/390272493892?pt=UK_Stamps_BritishStamps&hash=item5ade0da944

Alex.
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Gooner
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PostPosted: Sun Dec 19, 2010 6:14 pm    Post subject: Reply with quote

Difficult to tell from an eBay scan Alex - as they are very lo-res - but I would say it is the closest to the one on the left of the three that I scanned.


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garyhoney
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Joined: 11 Dec 2009
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Location: Surrey, England

PostPosted: Fri Dec 02, 2011 10:21 pm    Post subject: Reply with quote

What an excellent test.

I have a nice 3p OCP/GA coil stamp which until today I had never attempted to verify that it wasn't the lesser FCP/GA coil stamp.

So I took the advice above and dug out my British Rail prestige book and my Stamps for Cooks Book.

In the following image (taken under Short wave UV) the controls are on the right with the Stamps for Cooks above and the BR prestige below.



Looks like I didn't buy a dud. Very Happy

Thanks for promoting this test.
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Gooner
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PostPosted: Fri Feb 22, 2013 12:38 pm    Post subject: Reply with quote

Gary, have you "moved" or "removed" the image in the above text as I can no longer see it.

A lesson for all members here. If you delete or move images that you have loaded into the forum - they are lost to said forum.
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cdj1122
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PostPosted: Fri Feb 22, 2013 8:10 pm    Post subject: Reply with quote

I understand that the way to avoid losing an image such as one lifted from eBay or elsewhere is to post it on a site like Photobucket.com and then use the URL generated there for this site.
That should allow it to be kept in perpetuity or until a meteor strikes the cloud where Photobucket is perched.
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Gooner
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PostPosted: Sun Feb 09, 2014 1:11 pm    Post subject: Reply with quote

A year later and I am not sure I am any further forward.

I am looking at p 2B booklet stamps with attached labels.

Now this makes identifying the OCP from the FCP relatively easy as long as all the marginal perforation is available as the perforator "types" are different. Also some labels only appeared in FCP (e.g. Rushstamps - UB25).

However the issue I have is actually with the gum shade.
ALL should be PVA gum, yet some of the examples (about 50/50 actually) show a much whiter (if not quite a shiny GA) shade under both flavours of UV, than others which are very dull.

I was hoping at first that this would help me with the OCP/FCP debate but no I have two exactly the same "B.ALAN" label p stamps that can only be OCP (because the perforator type = P) and yet the backs are different shades.

Any clues anyone?
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reintjedevos
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Joined: 13 Nov 2014
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PostPosted: Thu Nov 13, 2014 7:10 pm    Post subject: Reply with quote

Whether OBA's are in the coating and to what degree is something that will not hold in time... The OBA will somehow disappear although you may postpone the moment by keeping your stamp - mint at least - in a save place!

I am having a fierce diacussion by now with Mexican collectors of the "Mexico Exportas" as they believe deeply in the presence [or the lack of it] of OBA's in the coating of several of their subsets (of the Mexico Exportas].

Everything seems fine for their mint stamps, but the moment you collect the used [and washed off] stamps, you will discover that ALL of the OBA's in the coating have disappeared!

What DEEGAM does not tell us is how to describe the various papers in terms of paper grain!



The long wire in the Fourdrinier paper machines can have a wove that can be of three kinds!

A symmetrical linen-binding = everything machie made in 1860-1938;
an asymmetrical twill-binding = from 1938 onwards;
a multilayer binding = from 1970 onwards.

Apart from that the density of the horizontal/ vertical lines is important. The wire of the above stamp is rather coarse, and both the horizontal as well the vertical density are more or less equal...

Which is not so in the case of the Silver Wedding:



Which leaves us with a lot to do in the Machin field Smile

Does anyone notice the blots in the gumming???



Does Doug Myall describe that???
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