Re: Pin holes in my litho
j.r.anderson ()
Fri, 24 January 1997 4:28 AM
>yOn Thu, 23 Jan 1997, j.r.anderson wrote:
>
>>
>> >
>> dots + white dots) can often appear on lith PAPER as well - this is said by
>> some to be cured by adding some sodium sulphite to the dev... something to
>> do with restraining the process without deactivating the dev.... but I find
>> it a very erratic and difficult problem to predict. Sometimes it's there,
>> sometimes it isn't. I wonder what theory people have for the black dot
>> problem?
>>
>> By the way, I have found that different paper types are much more or less
>> prone to these problems...
>>
>> Jonathan Anderson
>>
>>
>Sodium sulphite is not a restrainer, if anything while being a
>preservative, it is a accelerator. For example when Rodinal is mixed in a
>5%solution of sodium sulphite instead of water, the development times are
>almost cut in half. Litho developers are usually pretty concentrated and
>very alkaline. I have noticed black specks arising from minute
>undissolved particles of developing agent that sit on the paper and really
>cook it. This may or may not be the case in your case. Are you using a
>concentrated liquid developer, or mixing from powder?
>
>John
A good point about the sodium sulphite - I can't remember who recommended
this to me, but it is a bit back to front if I think about it. Mind you, I
don't know properly how the Lith Dev works, so I should probably keep quiet
at this point...
I use concentrated lith liquid, diluted a lot. I have not noticed that the
concentration affects the spots, but will have a look next time I'm doing
some. I mainly use Novalith (I think... I can't remember the name for sure
and I'm not in the dark room) Thanks for the hint. By the way, I know that
in theory it may be possible to alter the tone/colour of a lith print by
altering the ratio of A + B ("normally" used 50/50 in the mix, assuming
that anything at all in lith printing is normal...) Has anyone tried
playing with this? I tend to print on Oriental Seagull 101522.2625@compuserve.com (yes, it's good for
this process too!) for lith work. But many of you have probably already
worked out my fetish for this company's papers....
;-)
Jonathan Anderson
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