Question about modern Duofold materials Pearl and Black, and Grey Pearl and Black

[Paul-in-SF]

Both of these materials have a very swirly main color (Pearl or Grey Pearl) with a lot of chatoyance, and with ribbons of black running through it.

 

I've noticed that light does not reflect evenly across the surface where the black ribbons are. On any shiny cylinder, if there is a bright light nearby, you can get it to reflect in a thin line across the length of the cylinder. What I see with these two pens is that the reflected line is straight over the main color, but wherever the black ribbon crosses the reflected line of light, the reflected line is uneven, rather as if the black ribbons are sticking out slightly from the background. I can't really feel it, but I do see it.

 

What properties of these materials might account for this? Might the swirly main colors be a little softer than the black ribbon material, so that it wears down a little faster, leaving the black ribbons protruding very slightly over time? Perhaps there is enough difference in density that it is difficult even to produce an even cylinder. Would polishing (or especially over-polishing) exacerbate this effect?

 

This is a pretty technical question, and I realize no-one here may know enough about these materials to answer or even speculate meaningfully. However, I thought it was possible that someone might know about these materials or other similar combinations of materials to be able to shed some light. I hope this doesn't amount to asking a stupid question.

[vicpen123]

I tried the same with my Pearl and Black Duofold Centennial and the reflected line was straight and even for the length of the barrel. No difference.

 

 

 

 

[Paul-in-SF]

Interesting. Thank you for checking.

[baz666]

I don't know if there is any difference in the density between the black and pearl material, but this picture shows the manufacturing process of the pearl/grey and black Duofolds.

Vacumatics can suffer from this effect, if over-polished.

 

[Carrau]

I looked at this on both the Pearl and the Grey, and there does appear to be a subtle distortion (unevenness, as you described) of the reflected light.  Examining it with a loupe, the non-black material also appears to have fine silver particles that reflect light even more.  My guess is that the black (characteristically) is absorbing more light than the surrounding white or grey, and thereby creating this appearance.  Such beautiful and elegant materials.

[Paul-in-SF]

3 hours ago, baz666 said:

Vacumatics can suffer from this effect, if over-polished.

 

Do you mean the stacked celluloid materials? I have never noticed one like that, but then I haven't handled very many.

 

3 hours ago, Carrau said:

My guess is that the black (characteristically) is absorbing more light than the surrounding white or grey, and thereby creating this appearance.

 

A very sensible possibility.

[inkstainedruth]

I have not seen the Grey Pearl and Black.  I do have a couple of vintage Duofolds that are Pearl and Black (I really should see about getting them repaired and up and running at some point).

Ruth Morrisson aka inkstainedruth

[baz666]

1 hour ago, Paul-in-SF said:

4 hours ago, baz666 said:

Vacumatics can suffer from this effect, if over-polished.

 

1 hour ago, Paul-in-SF said:

Do you mean the stacked celluloid materials? I have never noticed one like that, but then I haven't handled very many.

 

 

Yes, the coloured celluloid starts to disintegrate, and when polished it is removed quicker than the black cap / clear barrel rings.

The effect in Vacs is known as "pickling".

 

[Carrau]

1 hour ago, inkstainedruth said:

I have not seen the Grey Pearl and Black.  

Ruth Morrisson aka inkstainedruth

Ruth,

Here are some links to the Grey Pearl and Black.  The pictures seem a bit darker grey than seeing the pen in person.  It’s not as striking as the Pearl and Black, but lovely all the same

https://www.bertramsinkwell.com/ecommerce/parker-duofold-international-pearl-grey-fountain-pen.html

https://www.peytonstreetpens.com/parker-duofold-international-fountain-pen-1998-grey-pearl-fine-18k-nib-near-mint-in-box-works-well.html