Digital BW, The Print

Most aluminum compounds are rather chemically active.  Does anyone have an opinion on 
what to expect in terms of print permanence from papers like the reportedly wonderful 
looking new Harman that uses an "Alumina" coating to control ink absorbtion?

Thor

"Alumina" is aluminum oxide (Al2O3). Here is a link with some  
information: http://en.wikipedia.org/wiki/Aluminium_oxide

It's pretty stable stuff. I've used it as a chromatography stationary  
phase. In this technique, one passes solutions of mixtures of organic  
compounds though a column packed with the stuff. The solutes are  
differentially absorbed which allows their separation as the solvent  
passes through the column. A wide variety of organic solvents can be  
used. Among other things, this indicates its general inertness to  
organic solvents. It normally doesn't cause problems for the solvents  
or solutes used in this process either.
Here's a reference to that process in the event that you're curious:  
http://en.wikipedia.org/wiki/Column_chromatography
Whether the stability of the alumina translates into stability of an  
image printed on this paper is another matter, about which I have no  
direct knowledge. However, I've tried the Harman Gloss FB Al paper  
(Epson 3800) and I like it.




On Oct 6, 2007, at 1:58 PM, t_j_l_s wrote:

>
> Most aluminum compounds are rather chemically active. Does anyone  
> have an opinion on
> what to expect in terms of print permanence from papers like the  
> reportedly wonderful
> looking new Harman that uses an "Alumina" coating to control ink  
> absorbtion?
>
> Thor
>
>
>


[Non-text portions of this message have been removed]

t_j_l_s wrote:
> Most aluminum compounds are rather chemically active.  Does anyone have an opinion on 
> what to expect in terms of print permanence from papers like the reportedly wonderful 
> looking new Harman that uses an "Alumina" coating to control ink absorbtion?
> 
> Thor

There's no independent fade testing of any of the Baryta 
(barite) papers including the ones with Alumina top layer so 
it will be difficult to get that information.

Henry Wilhelm says something about Barium Sulfate versus 
Titanium DiOxide and analogue RC papers but it goes a bit 
further than just RC papers. Interesting comments about 
Barium Sulfate and the use of OBAs in the second one.

http://www.wilhelm-research.com/phototechniques/PhotoTechniques_WIR_2005_01.pdf

http://www.wilhelm-research.com/pdf/HW_Book_17_of_20_HiRes_v1a.pdf


on Alumina: you can get a paper with two articles on Alumina

http://www.imaging.org/store/epub.cfm?abstrid=34162

http://www.imaging.org/store/physpub.cfm?seriesid=5&pubid=670

Degussa AG most likely is the supplier of what we see used 
right now, they have more varities

http://www.patentstorm.us/patents/6808769-description.html

You could make your own coating and tests based on that 
article :-)

The Alumina (or actually the manufacturing process) is in 
the first place created to give a gloss surface by its 
uniform, small particle size. I'm sure they will have tested 
the other aspects like fade properties as well. The PVA 
mentioned as the binder for the Alumina has good properties 
and is used in inkjet inks as well.

Aluminium pure is chemically active as it easily oxidises in 
a variety of environments. But quite inert in its oxidised 
form. What could be interesting to the use with inkjet inks 
is the anodising-eloxal process to give aluminium a nicer 
more durable finish with or without color. In that case 
several dye types are also used, see dyes at the bottom of 
this webpage article.

http://en.wikipedia.org/wiki/Anodising

The layer is afterwards sealed by further expansion of the 
top surface, encapsulating the dye component.



-- 
Met vriendelijke groeten,  Ernst


|  Dinkla Grafische Techniek  |
|     www.pigment-print.com    |
|             ( unvollendet )            |

Ernst Dinkla wrote:

> Henry Wilhelm says something about Barium Sulfate versus 
> Titanium DiOxide and analogue RC papers but it goes a bit 
> further than just RC papers. Interesting comments about 
> Barium Sulfate and the use of OBAs in the second one.

> http://www.wilhelm-research.com/pdf/HW_Book_17_of_20_HiRes_v1a.pdf

Following up on the comment above.

In the euphoria about Baryta papers it would be good to 
check one thing thoroughly: to get a whiteness equal to the 
TiO2 coating whitener as used in RC polyethylene and nonRC 
paper coatings a thicker Baryta coating is needed and I 
suspect more optical brightener. The Barium Sulfate 
refractive index is way lower than that of TiO2. The link 
above describes the advantage of barium sulfate not blocking 
UV light and by that giving the optical brighteners their 
best effect. The optical brightener can be added to the 
paper base instead or additional to the coating for the same 
reason. There are reservations about the use of optical 
brighteners and alternative whiteners. UV stability of both 
are not at the level of TiO2. That alternatives for TiO2 are 
sought is not just for nostalgic (darkroom) reasons, TiO2 is 
more expensive so blends with other (cheaper) whiteners are 
made and other whiteners are developed to give them TiO2 
specs, primarily by getting the particle size and uniformity 
close to that of TiO2. The new Alumina mentioned is one 
example but Alumina itself in clay coatings isn't new. What 
Baryta content actually is used in the paper coatings is a 
mystery. The Sihl Baryta specs mention a high Barium Sulfate 
content but not that it is the sole whitener in the coating. 
There is little or no optical brightener in that paper and 
both base and coating color are warm. It is hard to check 
how good development has been on substitutes for TiO2 not 
just in their opacity and whiteness but also in relation to 
stability in time. One thing is sure, the Baryta coating on 
inkjet papers of today isn't an exact copy of the analogue 
Baryta coating of >10 years ago.


This was written in 1999 (hard to read in Firefox, Explorer 
is good):

http://www.allbusiness.com/manufacturing/plastics-rubber-products-manufacturing/294696-1.html


-- 
Met vriendelijke groeten,  Ernst


|  Dinkla Grafische Techniek  |
|     www.pigment-print.com    |
|             ( unvollendet )            |

Ernst, I'm under the impression that alpha-cellulose and bamboo papers
are free, or relatively free from whiteners...

...because the fibers themselves are inherently bleached thoroughly,
unlike more whitened papers, including the new conventional papers
that are Baryta-coated.

Is there anything to that? 

Why are (some) alpha-cellulose papers so much more white than most
whitened cotton papers? ...Thinking here of Inkjetart's micro-ceramic
and Legion's LaSal (and the old Moab's Kayenta). 



--- In DigitalBlackandWhiteThePrint@yahoogroups.com, Ernst Dinkla
<E.Dinkla@...> wrote:
>
> Ernst Dinkla wrote:
> 
> > Henry Wilhelm says something about Barium Sulfate versus 
> > Titanium DiOxide and analogue RC papers but it goes a bit 
> > further than just RC papers. Interesting comments about 
> > Barium Sulfate and the use of OBAs in the second one.
> 
> > http://www.wilhelm-research.com/pdf/HW_Book_17_of_20_HiRes_v1a.pdf
> 
> Following up on the comment above.
> 
> In the euphoria about Baryta papers it would be good to 
> check one thing thoroughly: to get a whiteness equal to the 
> TiO2 coating whitener as used in RC polyethylene and nonRC 
> paper coatings a thicker Baryta coating is needed and I 
> suspect more optical brightener. The Barium Sulfate 
> refractive index is way lower than that of TiO2. The link 
> above describes the advantage of barium sulfate not blocking 
> UV light and by that giving the optical brighteners their 
> best effect. The optical brightener can be added to the 
> paper base instead or additional to the coating for the same 
> reason. There are reservations about the use of optical 
> brighteners and alternative whiteners. UV stability of both 
> are not at the level of TiO2. That alternatives for TiO2 are 
> sought is not just for nostalgic (darkroom) reasons, TiO2 is 
> more expensive so blends with other (cheaper) whiteners are 
> made and other whiteners are developed to give them TiO2 
> specs, primarily by getting the particle size and uniformity 
> close to that of TiO2. The new Alumina mentioned is one 
> example but Alumina itself in clay coatings isn't new. What 
> Baryta content actually is used in the paper coatings is a 
> mystery. The Sihl Baryta specs mention a high Barium Sulfate 
> content but not that it is the sole whitener in the coating. 
> There is little or no optical brightener in that paper and 
> both base and coating color are warm. It is hard to check 
> how good development has been on substitutes for TiO2 not 
> just in their opacity and whiteness but also in relation to 
> stability in time. One thing is sure, the Baryta coating on 
> inkjet papers of today isn't an exact copy of the analogue 
> Baryta coating of >10 years ago.
> 
> 
> This was written in 1999 (hard to read in Firefox, Explorer 
> is good):
> 
>
http://www.allbusiness.com/manufacturing/plastics-rubber-products-manufacturing/294696-1.html

> 
> 
> -- 
> Met vriendelijke groeten,  Ernst
> 
> 
> |  Dinkla Grafische Techniek  |
> |     www.pigment-print.com    |
> |             ( unvollendet )            |
>

I know. It is all a science experiement and we are the lab animals.

Breathing Color has the bright white rag paper and canvas out there
now that they promote as having no obs's at all. They do give the
illusion of better gamut and dynamic range, and make Photorag for
instance look off white. It becomes a situation of terminology. What
is an oba, and does another whitener ( almost all papers have some
kind of whitener) have any added stability benefits, or could they be
worse.

john






 It is hard to check 
> how good development has been on substitutes for TiO2 not 
> just in their opacity and whiteness but also in relation to 
> stability in time. One thing is sure, the Baryta coating on 
> inkjet papers of today isn't an exact copy of the analogue 
> Baryta coating of >10 years ago.
> 
> 
> This was written in 1999 (hard to read in Firefox, Explorer 
> is good):
> 
>
http://www.allbusiness.com/manufacturing/plastics-rubber-products-manufacturing/294696-1.html

> 
> 
> -- 
> Met vriendelijke groeten,  Ernst
> 
> 
> |  Dinkla Grafische Techniek  |
> |     www.pigment-print.com    |
> |             ( unvollendet )            |
>