Re: Gum woes revisited

From: Katharine Thayer ^lt;[email protected]>
Date: 05/20/05-04:51:06 AM Z
Message-id: <428DC119.34E@pacifier.com>

This is a P.S. to my earlier post, which hasn't arrived back here yet;
the P.S. goes with the speculation about different yellow and magenta
pigments working best with the different types of cyanotype:

P.S. Though it's true that as I and others have said before, the fact
that people get decent color balance with a wide range of different
combinations of pigments shows that tricolor gum is probably more
forgiving than it's sometimes given credit for, so perhaps that
speculation assumes a higher level of specification than is necessary
for the purpose.
kt

Scott Wainer wrote:
>
> Hello all,
>  
> Just an update on my journey into gumland. After changing almost
> everything I was doing I began to taste success, except for a slight
> problem of not being able to get a smooth first coat (cyan printed
> using ultramarine). After a little head scratching and reading Sam
> Wang's article on 3 color gums (unblinkingeye.com), I tried using
> cyanotype as a first coat. It was a mess, even with a change of paper
> (to Fabriano Uno) I still had a hard time getting the first coat of
> gum smooth (this time with lemon yellow). More head scratching and I
> decided to give the paper a second coat of sizing and to dilute my
> pigment/gum solution even more. Everthing worked perfectly. Here's
> what I came up with:
>  
> Paper:
>      Fabriano Uno
>      preshrink by soaking for 1 hour at 140F
>           allow to dry before sizing
>      2 brush applications of 3% gelatin size
>           30gm gelatin + 3gm Chrome Alum per liter
>  
> Cyan base:
>      New Cyanotype (1.5ml for a 5x7 image)
>           add 2 drops 5% Tween20 per 10 drops of sensitizer
>           add 2 drops 40% citric acid per 10 drops of sensitizer
>  
> Pigment/Gum:
>      pigments - Winsor & Newton artist grade watercolor
>           Lemon Yellow for yellow separation
>           Cadmium Red for magenta separation
>      gum - Daler-Rowney (light amber)
>      ratio - 1gm pigment to 20ml gum
>  
> Process:
>      1. print image in cyanotype using digital negative with cyanotype
>          curve applied - printed and processed as a normal cyanotype
>          approximately 5 minute exposure - 10 minute development -
>          peroxide bath - 10 minute wash - blowdry on hot 10 minutes
>  
>      2. yellow separation -
>          apply pigment/dichromate at 1+1 and allow to dry 1 hour -
>          sensitizer went down very smooth - no blending required -
>          expose 2 minutes and develop for 1 hour in 3 still baths -
>          dry overnight
>  
>      3. magenta separation -
>          apply pigment/dichromate at 1+1 and allow to dry 1 hour -
>          sensitizer went down very smooth - no blending required -
>          expose 2 minutes and develop for 1 hour in 3 still baths -
>          dry overnight
>  
> Changing to a more dilute pigment/gum ratio and adding the second coat
> of size did wonders - no more worries. While the colors (as I see
> them) are different from the original I like what I am getting and
> will try other colors in the future.
>  
> Thanks to everyone for their help, Scott
>  
> swphoto@verizon.net
>  
>  
>  
>  
>  
>  
>  
>  
>  
>  
>  
>  
>  
Received on Fri May 20 15:49:54 2005

This archive was generated by hypermail 2.1.8 : 06/02/05-10:12:02 AM Z CST