Centennial Stamps Different Papers

I've recently purchased quite cheaply a lot of used centennial definitives, I've firstly sorted them in type by value and then by sheet / booklet / coils / etc… I then want to look at paper types which is a fairly new subject for me.
I've attached a picture of the 1c sc454, under normal light they all look the same, except for those with tagging on and the right hand column which are booklet stamps. However under UV light in a darken room some of these look brighter than others, I also attach a picture of some of these.
Is this different paper types ?

If you do not yet have a Unitrade Catalogue of Canadian stamps then I would recommend that you get one.

The following is a table of the Scott/Unitrade 454 stamp variations. You will find it difficult to identify Used versions of this series.

Centennials!!! argghhhhhhhhh

So many choices and printings.
Just for the 1c there is 6 different paper types. ranging from NF,DF,LF, HB, LF/fl, NF/fl.

There were 5+ plates used over 6 years, so lots of possibilities. And this doesnt even cover the Booklet papers and perforations.

If you want to explore that era, I would suggest the Unitrade Catalog or the specialized Catalog "Centennial Definitive Series, 1967-1973" by Robin Harris(who also happens to be the Unitrade Editor)

When collecting Centennials, the Hibrite paper is the premium type of paper for most.

I would just try to collect the 4 major paper types when using used stamps.

Trodent

Brixton Chrome has an informative series of articles on the Centennial series, covering paper types among other things.

Starts with this one - https://brixtonchrome.com/blogs/can...sue-part-one

Many thanks for assistance and links…much appreciated.
Can I assume that the whiter paper showing under UV is the Hibrite

Hibrite paper came from a specific paper manufacturer. I cannot remember who at present but possibly a UK supplier. The other papers came from various producers as and when stock was available.

The non Hibrite fluorescent grades are caused by different amounts of optical brightener additives (OBAs) being added to the pulp at the paper making stage to correct the visual appearance of the finished paper under daylight.

How much was added depended on the source material for the paper. The different grades of fluorescence you see under UV are just an accidental effect of the paper making process not the stamp printing process and was of no concern as far as the stamp printers were concerned they just wanted a visually white stock. The paper stock was never intended to be viewed under UV light.

I assume different paper manufacturers may have used slightly different OBAs. Another way of getting a whiter paper is to add a "bleach" such as sodium borohydride to the pulp to remove traces of colour. This is not fluorescent and may account for the non fluorescent paper.

The OBAs are similar chemically to dyes and are water soluble. So you have to be careful in looking at soaked off used stamps as the soaking MAY have changed the fluorescence from what it was in the mint stamp.

These brighteners are usually sulphonated stilbenes (if you are interested in the chemistry). There are a lot of web articles about them. A simple starting point is

https://en.wikipedia.org/wiki/Optical_brightener

AQ

Also be aware that optical brighteners are also added to some dish washing liquids**; folks who 'add a drop or two' of liquid soap when soaking their stamps can artificially change what you might see under a UV light. In my book, IDing used stamps can be quite dicey at times.
Don


**Manufacturers of dish washing soap are NOT required to list their ingredients, so collectors cannot tell if a particular soap has optical brighteners or not.

See the following webpage: https://adminware.ca/checklist/chk_centennial.htm