Digital BW, The Print

On 08/25/2012 09:38 PM, ClaytonJ wrote:
> Hello Ernst,
>
>  > There is now a discussion about Museo Silver Rag on the LL forum.
>
> Thanks, I'll have a look.
>
>  >Is the yellowing happening more on the coating side or more on the
> paper base?
>
> I don't have any sort of instrument to measure the color or intensity,
> but to my eye the yellowing is equal on the back uncoated side. It
> occurs on all four edges equally. As for intensity, it is not bright
> yellow (it doesn't look at all like the bright chemical yellowing we
> used to see on H. Photo Rag, for example), but is rather faint, but
> distinct. The hue is yellow, not brownish.
>
>  >Did it transfer to the papers directly in contact with the MSR?
>
> I don't think so, I checked the others again. I don't know which prints
> were the ones in direct contact, but none of them have yellowing like
> these five. Some are dirty and have some odd stain spots (one looks like
> something was spilled on it), but nothing like the even 4-border effect
> of these five. When I found the stack I stopped work and sat down to
> examine the prints, which brought back a lot of memories. The stack was
> about 5" tall. The 5 MSR prints were together, and down at about the 2"
> level, so it took awhile to get to them. The yellowing is distinct
> enough that I had an immediate reaction when I saw the first one. None
> of the matte prints had the yellowing. They were on a variety of papers,
> both OBA and non-OBA versions (VFA, Condor BW, Soft Textured Art, EEM,
> Photo Rag, Aurora Art, etc).
>
> Regards,
> Clayton

Hello Clayton,

It must have been something that was in that paper from the beginning. I 
presume you did not rinse that paper for some reason. A sprayed varnish 
would show on one side only. Contamination, particles from the air 
around it, packaging etc most likely would have affected the other 
papers in the stack. Biological processes usually are not contained 
within the paper itself but transfer byproducts to the other papers in 
contact. If it is all around the edges light may not be the cause but 
more likely oxygen etc. Light would be less even around the edges with a 
stack in a bookshelf.

Sizing of the paper or an anti-curl coating at the back with the same 
bad binder as used in the top coating. Bad batches of cotton fiber. 
Exposure to daylight might work if it is a sulfur or nitrogen effect. If 
it was oxygen or light it could worsen the effect. Nothing wasted to try 
that with one sheet, I guess.

-- 
Met vriendelijke groet, Ernst

Dinkla Grafische Techniek
Quad, pi\ufffdzografie, gicl\ufffde
www.pigment-print.com