How To Differentiate Ordinary From Chalky Paper? Swiss Stamp

Hello
I experience difficulties with the differentiation of the type of paper (x or y) for the swiss stamps
Helvetia with sword (Zumstein 113,140, 141) & Coat of arms (Zumstein 163,164, 165).
The paper X is ordinary paper and the paper Y is chalky paper (kreidepapier)
Both have smooth reverse.
I have checked on the web if there is an answer about my problem, but I didn't found something probative.

Do you have a trick or an advice for making the difference between these papers ? ( UV light….?)
Or have you some web addresses where this question was solved?

I have a 6V UV lamp; is it powerful enough?

Thank you

Priatel, this is a subject that has been thoroughly discussed on this forum. If you use the search function above you will find all the posts that address this type paper!

Peter

Chalky paper has an additive on the top surface which gives the paper a smoother finish. When the stamp image is printed on chalky paper, the ink doesn't soak in as quickly and the printed lines will often show pooling of the ink. This distinctive look to the lines is pretty easy to see under magnification so can help in determining if the paper is chalky. The other method is to use a bit of silver wire and touch the surface. The silver will tarnish enough to leave a dark spot where it touches the paper. I only suggest that on cheap stamps though, since the mark left behind will devalue the stamp, but a couple of cheap ones can give you a better idea as to what to look for in the inking.

If one is familiar with the "coated paper" used in glossy magazines or catalogues, that is probably the best way to begin to understand "chalky paper." So chalky paper stammps have a smoother, glossier finish.

Don't soak any stamp that you think might be chalky paper. Soaking will damage the coating and the ink on the coating.

Thanks to all.

But I would like to know how to make the differentiation using a UV lamp. Manner of use, necessary power...

My question concerns only the above-mentionned Swiss stamps; because , may be, other chaulky stamps from other countries will react differently.

Priatel, going through all the different threads on this subject it became clear to me that using a UV lamp to determine chalky paper ( Kreidepaper ) not very certain. As you said, chaulky paper from even the same country reacts different sometimes!

Peter

I have read all the posts I found here and on other fora about that theme.
But I didn't found a method which give with certitude.

The silver method is a destructive method...and so, I forget about it!
The gloss estimation is very unprecise and I don't know if we receive an absolute certitude.

What else?

May be increasing the power of the UV lamp??
May be using an other lamp ? ( using colored bulb)
May be... Don't you have ideas?

I think that IT MUST exist a method which give 100% certitude, but which one??

If someone has a "trick"....

thank you

Working with stamps is not a form of engineering that brings with it 100% certitude. It is not a bag of tricks. It is an art and skill achieved over time. To exercise the art, time and energy are required. Nothing can replace the expert opinion of those who have seen thousands of chalky paper stamps and who also maintain reference collections of proven examples of whatever feature is at issue.

The rest of us have two choices: submit our doubts to recognized authorities or live with some degree of uncertainty until we can gain sufficient experience and sufficient reference material to reduce our uncertainty.

I have an additional question concerning the chalky paper stamps.

Let's take as example the Swiss stamps Zumstein 163-165 (Michel 194/196 – Scott 200/202).
These stamps are available with 3 types of paper:
Type X : traditional, normal paper
Type Y & Z : chalky paper
- type Y has a smooth gum
- type Z has a grilled gum (the grill can be seen on the paper even when the gum has disappeared)

So, looking the stamps from the picture side , we can make the difference between the type X and the types Y, Z ( let's suppose that the determination of chalky or not is done- posts here above)

And for making the difference between the types Y & Z, simply check the gum side for the grill.

This looks perfect!

BUT

What about a chalky stamp on a letter ? How to determinate his type? Z or Y??

This is very important to be possible to be done if we look the value of the stamp.
On a letter, the #664; 165 Z has a catalogue value of 100 CHF and the 165Y has a 7500 CHF one!

Thanks for your help