Hi, i'm new here. I was looking for any guide to the basics of B&W papers; what is fiber based for example. If u know any site please tell me.

thanx

-- ahmad hosni (xosni@gega.net), December 03, 1999

Answers

It's a misnomer, because all paper is fibre based. However, some paper has a resin (plastic) coating on each side of the paper, which prevents the chemicals from soaking into the fibres. This is known as resin-coated, RC, or plastic. The non-resin-coated paper is usually called fibre-based or FB.

-- Alan Gibson (Alan.Gibson@technologist.com), December 04, 1999.

Yes, but what is the difference between both???????????? How can i choose?

-- ahmad hosni (xosni@gega.net), December 04, 1999.

The RC papers don't absorb water into the paper base so they wash much faster and dry much faster, so you save time and agrivation in processing them. The trade off is that they may be more subject to deteriation with time; the early RC papers self-destructed in a year; the manufacturers claim that the current ones are just as stable as the FB papers, but it's too early to verify this. Most phtotgraphers do their ordinary work on RC papers, saving the FB paper for "exhibition" quality prints. The highest priced papers (with more silver) only come in FB. The key work here is "Convenience." It's also usually less expensive in the long run. Unless there is a cardinal reason for doing otherwise, you should always start with RC papers, at least until you become a master printer.

-- Bill Mitchell (bmitch@home.com), December 04, 1999.

FB vs. RC material

Image quality: FB afficionados often claim that FB prints have a better quality. The fact is that exquisite FB papers contain much more silver in their emulsions than RC papers. This may enable blacker blacks and a better scale of grays. At least when they are put behind glass, however, you will hardly notice any difference between otherwise identical RC and FB prints. (See also logevity below.)

Ease of handling: RC is definitely easier to handle as it does not get soaked with chemicals. The washing time is consequently much shorter (a few minutes in running water), it dries nice and flat w/o further effort. FB, otoh, should be treated w/ a hypo eliminator to keep washing times acceptable (i.e. 20 to 30 minutes in running water). It usually curls during drying unless you use a press. The curling can be remedied by putting the prints between heavy books or the like for a couple of days when they are dry.

Price: As a rule, FB is more expensive, but there are also fine and affordable FB papers and expensive RC stuff.

Longevity: Properly processed (and stored) FB prints can live quite long, even untoned. When toned in selenium, sepia, or gold toner, they can easily last for centuries. There is some dispute about the archival quality of RC material. Personally, I have some RC prints which I made in the early eighties. They are stored in folders, and I haven't seen any serious deterioration yet. When placed on display, i.e. in light, and especially behind glass, RC is said to deteriorate much faster. In their fact sheet, Ilford (e.g.) state that RC prints will last long enough "for most purposes", whatever that means. Note that it is not the silver image itself that is in danger here (you could easily stabilise that using the toners recommended for FB above) but the resin-coated (whence RC) base. Personally, I bet on FB (toned) for prints that are supposed to last at least long enough for my daughter to show them to her children.

Toning: As a rule, FB emulsions will more easily show considerable changes in tone when treated with (e.g.) sepia.

Touch: A print on a heavy museum-weight base feels different from one on RC paper. Still, there is (at least) Ilford's Portfolio material to help that.

-- Thomas Wollstein (thomas_wollstein@web.de), December 06, 1999.

"The fact is that exquisite FB papers contain much more silver in their emulsions than RC papers."

Here's some comments made by Richard Knoppow, one of the sharpest shutterbugs on the 'net: The idea that a paper has to be "silver rich" is plain nonsense. Most papers have just about the same concentration of silver in the emulsion, just around 2mg/sq in. The shape of the developed silver grains can have an effect on their covering power. The true Dmax of a paper is seldom reached in actual practice because normal negatives and normal printing times just don't expose the least sensitive silver grains. You can prove this by making a test exposure of a scrap of paper exposed to room light. Compare it to the max black you get from an enlarger exposure by looking through the paper. Mostly you will find the paper that has really been socked is just a bit darker. This extra density is, however, pretty useless in a reflection print. If you can achieve a reflection density of 1.8 you are doing very well. The Dmax of RC and fiber are about the same. The somewhat differnt surfaces can make them look a bit different. The only source of data on silver content is in Dr. Richard Henry's book _Controls in Black and White Photography_ second edition, (1986) Focal Press, ISBN 0-240-51788-1 He has a chart showing the silver content and Dmax for several papers on p.51 The silver content varies from 0.84 mg/in^2 for Kodak Elite grade #1 to 1.68mg/in^2 for Kodabromide, grade #5. The Dmax of the Elite is 2.31, the Kodabromide 1.95. The greatest Dmax on the chart is Ilford Galerie, grade #3 with 2.39 and 1.01 gm/in^2 slver, the lowest Dmax Kodabromide, grade #1 with 1.90 density and 0.88mg/in^2 silver. From comparison of the various papers listed there seems to be no relationship between silver content and Dmax either toned or untoned. The above densities are un-toned. The covering power of the silver in the image will be dependent on its structure more than the amount. I have no figures on the current Ilford papers but it seems the avarage silver content for all the papers listed is around 1.0 mg/in^2

-- Tim Brown (brownt@ase.com), December 06, 1999.

Tim,

I didn't say that a paper *has* to be silver-rich to give good blacks, but that the exquisite FB paper does, as a rule, contain much more silver than the RC stuff, which is often given as the reason for its alleged better image quality.

Although you do not expressly say so (and I do not know all the brands of paper you name), I seem to read between the lines that you found in the table you quote that, on average, RC paper contains about the same quantity of silver per unit area as FB paper. This is interesting indeed, because the lack of silver in RC emulsions is generally said to be the reason why RC papers (with the exception of one special Kodak paper) do not lith print.

Perhaps you can help me to understand the mechanisms better: When light hits the paper, part of it reaches the white base where it is reflected back, again through the silver layer. So, to a first approximation, I would expect the reflection D_max to be about twice the transmission D_max.

The approximation consists in neglecting that the base is less than 100% reflective, and the effect of reflection from the surface. The latter mainly reduces the effective D_max of a matte-surface paper as compared to an otherwise identical glossy paper, because in the blacks, the little diffusely reflected light makes a difference whereas it doesn't in the highlights. The first will lead to the reflection D_max being somewhat less than twice the transmission D_max. I would expect this effect to lie in the range of 0,3 log D units guessing that the reflectivity of the paper base is usually around 92% (back of Kodak Gray card).

(Forgive me for elaborating on what might seem to be boring theoretical, or scientific stuff for some of the readers. Although I hardly ever think consciously about the physics and chemistry involved when I am printing, I am sometimes curious about it, and I do think it sometimes helps when tackling specific problems.)

-- Thomas Wollstein (thomas_wollstein@web.de), December 07, 1999.