Digital BW, The Print

Daniela wrote:

> Coating is applied for several reasons:
> 1) Deeper blacks (L* goes from 21-uncoated to about 11 after coating)

I might add that I hit a dmax of 2.5 with Arches un-coated water color 
paper when I applied a coating.  The problem I had with the coatings & 
methods I was using is that the fibers of the paper continued to 
occassionally stick out through the coating, making it look a bit 
funky.  Of course, these coatings take a lot of work, which is a double 
edged sword.

> 2) Protection of the print (gelatine based emulsions are not permeable
> to water)

I fade tested a coated matte paper print where the fader was sitting in 
a pan of water.  The idea was to try and get the humidity up as high as 
possible.  One of the major criticisms of accelerated fade testing is 
that the process dries the pigments, thus exaggerating the life.  

The results of the fade test were interesting.  The coated print faded 
about 20% more than the un-coated on.  My hypothesis is that the water 
vapor was getting in through the back of the coated print and being 
held there, whereas the un-coated control print was allowing the 
moisture to quickly evaporate off the front of the print.  Note that I 
am not suggesting that this test replicates the real world. 


I'm curious how you're applying the coating.

Good luck with the process.  It sounds intersting and should 
distinquish what you're offering from the everyday inkjet printing.

Paul
www.PaulRoark.com