U of S | Mailing List Archive | alt-photo-process-l | Re: Family snaps to gum bichromate

Re: Family snaps to gum bichromate

On Fri, 13 Apr 2007, Camden Hardy wrote:

 ....However, as Judy noted, gum is not
the most detail-oriented process out there.  So it may not matter in the
long run how you go about making your color separations.  I would say try
each of your 3 methods and choose the best (quality/price/ease) one and go
from there.
I'd agree with Camden's suggestion about comparison testing, but... watch it on the "not detail-oriented" stuff, which may be too close for comfort to the old canard (actually beyond canard, into shibboleth, even formerly on the Photographers' Formulary website) that "gum can't do fine detail." I'm sure he didn't mean that, rather pointing to the fact that folks hung up on sharp crisp tight infinite perfect detail would tend to go to another process (which shall here be nameless) rather than one where the paper can get twisty or other hazards of multiple coats can have a softening effect, and indeed there is that dot gain.

For the record, however, gum can get EVERYTHING in the negative if the curve fits... there is however bound to be more dot gain in gum printing than in almost any other process (except maybe offset on blotting paper), which is why 300 dpi is plenty, but then it's apparently plenty in any repro medium, including digital.

As Camden notes below.


Išll also confirm what Katherine said about printing resolutions.  Since
youšre looking at making gum prints roughly the same size as the original
4x6 prints, 360dpi is really the highest youšll need (if youšre looking to
print bigger youšll need to scan at a higher resolution).  Išve even made
gum prints at 300dpi and I couldnšt tell the difference next to a print made
at 360dpi.  I wouldnšt recommend going down to 240dpi though.

Camden Hardy


On 4/12/07 6:48 PM, "Ender100@aol.com" <Ender100@aol.com> wrote:

Scan the negatives and then use Photoshop for the seperations.

In a message dated 4/12/07 6:02:20 PM, don@sweetlegal.co.nz writes:

I would be grateful for guidance on this topic (details of which are covered
in the archives I know).


 Among my 30+ years of family snaps are some that I see as potential 3-colour
gum pictures, about A4 size or maybe slightly bigger.  Many of the surviving 6
x 4 prints are tatty and faded (and some have been re-worked in what appears
to be an expressionist manner with felt pens, scissors, etc).  Most of the
35mm negatives are pretty good.


 Would anyone in the group like to recommend whether I should produce the
necessary negatives:


 1.    Taking the best negatives to be scanned by a photo processor -  I
have been quoted a resolution of 1200 dpi - and use Photoshop to make colour
separations, or


 2.    Get some more 6 x 4 prints made by a photo processor and scan them
myself at something like 400 dpi, and then use Photoshop, or


 3.    Make colour separations myself on document film using a slide copier
and filters, and enlarge them on to lith film.




 Don Sweet

Best Wishes,
Mark Nelson

Precision Digital Negatives - The System
PDNPrint Forum at Yahoo Groups <http://groups.yahoo.com/group/PDNPrint/>
www.MarkINelsonPhoto.com <http://www.markinelsonphoto.com/>

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