Re: Gum woes

Re: Gum woesHi Hamish,

Changing the gum/pigment/dichromate ratio helped but the emulsion still seemed to separate when applied to the paper. I just finished up my stack of gelatin sized Lenox and wanted to see if the paper was part of the problem so I took a piece of unsized Lenox and coated it with an emulsion of 1g pigment per 20ml gum mixed 1+1 with dichromate. The paper just soaked it up - taking almost 6ml emulsion for an area a little bigger than 5x7. With a 2 minute exposure and a 60 minute still water bath all I got was a red square and no image - talk about staining. So the Lenox is now reserved for other processes. But I did notice that the emulsion did not separate so maybe it was the size after all. Digging around in my paper pile I found 25 sheets of Fabriano Uno and 25 sheets of Arches Aquarelle (both 140lb hot press) which i'll try this week. I also found some Coventry Rag and Strathmore Drawing Bristol which I might try but the Coventry looks to be just as thirsty as unsized Lenox and I doubt the Strathmore will hold up under the required soaking. I'll have to get some Artistico and give that a try too, in addition to other colors.

Regards, Scott

swphoto@verizon.net

  ----- Original Message -----
  From: Hamish Stewart
  To: Alt Photo List
  Sent: Sunday, May 08, 2005 7:35 PM
  Subject: Re: Gum woes

  Scott,

  I don't want to repeat too much of what has already been said but a few quick points

  I have always found that a simple ratio of 1:1 of the gum+pigment and the dichromate works just fine - I have never added any additional water at all. On occasion I might increase the ratio of the dichromate. I have used both ammonium and potassium - what works best will depend on your lights and your negatives.

  Your pigment load seems high to me - I tend to work with between 1-3g tube pigments to 12ml gum. Stronger pigment load will give you more intense colour but will increase the potential for pigment staining

  I am not familiar with the paper you are using - Kerik's suggestion of Fabriano Artisco is a good one - I have used this for quite a few years and the hot pressed surface works very well with gum

  You might also want to use some different tube colours - I recall that windsor & newton colours - windsor blue, alzarian crimson and cadmium yellow all worked well for me in the past.

  Best of luck with three colour printing!

  Regards

  Hamish Stewart Gum Bichromate Photographer - http://www.gumphoto.co.uk

     
Received on Sun May 8 20:10:05 2005