Most Machins, pre decimal and decimal were printed on unwatermarked coated paper ( uncoated errors do exist ). Seven basic types have been used up to this time of the printing of the current issues. These are listed as follows:
Original coated paper
OCP: Is off white in to cream in colour and shows a dull reaction under the ultra violet light.
Fluorescent Coated Paper
FCP: Was Introduced late in 1971, it is much whiter than OCP and has a strong fluorescent white reaction when viewed under the ultra violet light.
Phosphor Coated Paper
PCP: Was experimental and tested with the large 10p cerise issued in 1970. It was also used to print the 50p in 1973. Improved coatings were tried and tested on the 4.5p with two bands added, also on the 8.5p in 1976.
Phosphor Coated Paper 1
PCP 1: Developed and introduced in 1979, consisting of three values at first 11p, 13p, & 15p, more values were added as stock ran down or was replaced to reflect new postage rates. The coating appears mat and has a weak response to ultra violet light.
Phosphor Coated Paper 2
PCP 2: This has a highly glossy finish compared to type 1, it reacts to ultra violet light much better. It also shows a photo negative reaction to the portrait when the stamp is held flat up to a light at eye level. The Queens head resembles a photographic negative, and it is easily distinguishable from the rest of the surface.
Pre Printed Phosphor
PPP: This was a short lived experiment with a pre printed phosphor coating applied to the paper. The phosphor was printed directly, then the ink was additionally applied during the printing process. The stamps having a matt looking appearance. Only three values were issued, the 1p, 2p, and 10p
Advanced Coated Paper
ACP: Another experimental printing in 1983, the paper gives off a better reaction than PPP, and shows a greenish hue under the UV lamp, it also looks much whiter than PCP & PPP.
Optical Free Phosphor Paper
OFPP: First issued in 1995 with the 25p first class stamp, also the 1st and 2nd class None Value Indicator stamps. Other values have since been added with elliptical perforations, these are available from the Jeffrey Matthew’s miniature sheet and Her Majesties miniature sheet released for the Stamp Show 2000.
Optical Free None Phosphor Paper
OFNP: As above with phosphor bands incorporated into the printing process, nearly all of the current new issues now have this type of paper, it is said to be more eco friendly. This is the last of the nine well known papers used to date, but for how much longer? We will keep you abreast of any new developments that may arise. See Machin News
Other papers used that deserve a mention
Contractors Paper: Bradbury and Wilkinson supplied their own paper for the certain issues of the large recess printed stamps (i.e. £.s.d ). This was thinner than the original post office OCP paper.
Uncoated Paper: Stamps printed on this type of paper do not react to ultra violet light and ink diffusion gives off a blurred design. Normally a thin paper which will show the design of the stamp when viewed from the rear.
Silicone Coated Paper: Another experimental printing. A silicone coating was applied to certain strips of stamps (coils). These were sold through Post Office vending machines. The direct aim was to stop these stamps from sticking together whilst coiled in the machine. This coating tended to dull the surface of the stamps.
De La Rue Byfleet & Dunstable Papers
I have recently had a lot of mail asking about the different papers/ gums originating from De La Rue printings at Byfleet and Dunstable. Hopefully this will help.
RMS Paper known as (Royal Mail Standard ) or ( Specification ).
This is the paper currently used at Dunstable for all current printings , Known in certain circles as ATN (c). This has a cream PVA gum and is dull in appearance when viewed under a UV light. It is designed to get as near to that of HS2 paper used previously by Harrisons at the High Wycome factory.
TR3 Paper is the term for used for printings originating at Byfleet. There are 3 main types with variations of OBA in the coating.
Dull, Intermediate and Bright Papers.
TR3 - d = DULL : TR3 - i = INTERMEDIATE : TR3 - b = BRIGHT (it is believed by some that this paper was also used for a very short period at Dunstable but others disagree).
These papers above can be sub catagorised into (with) different 2 gums. ATN (1) - Layflat gum. ATN (t) - Tinted Gum.
HSC is another paper used during this period. A single paned dull paper with Layflat gum (imported from Enschede) due to the fact only single panes could be used ( printed in sheets of 200 ). Only no dot cylinder blocks were available from this printing.