9 replies to this topic

[Deardorff Dave]

I made a batch of carbon tissue paper last year. I used 10% photo gel and added 20% non waterproof indian ink. Does carbon tissue paper have a use by date? Or can I keep manufacturing a good stock ready to use.

[pschwart]

The fresher the better, but if the unsensitized tissue has not been subjected to extreme heat or humidity then it may be fine. A simple test: put a small piece of unsensitized and unexposed tissue in water about 105-110 F. The gelatin should melt completely, leaving a clean substrate in 5-10 minutes.

Gelatin will spontaneously harden over time even if not exposed or sensitized, so I try not to get too far ahead in tissue production. Freezing tissue in ziploc bags will extend viability, but I have used unfrozen tissue a year old with success. Sensitized tissue must be used *immediately* after drying or else frozen in ziploc bags. Even frozen, sensitized tissue cannot be stored indefinitely. Frozen tissue may lose moisture (look for curling) and this will signifcantly alter the way it behaves and may even cause the gelatin to crack when flexed.

Deardorff Dave, on 29 December 2011 - 08:06 AM, said:

I made a batch of carbon tissue paper last year. I used 10% photo gel and added 20% non waterproof indian ink. Does carbon tissue paper have a use by date? Or can I keep manufacturing a good stock ready to use.

[Deardorff Dave]

pschwart, on 29 December 2011 - 12:19 PM, said:

The fresher the better, but if the unsensitized tissue has not been subjected to extreme heat or humidity then it may be fine. A simple test: put a small piece of unsensitized and unexposed tissue in water about 105-110 F. The gelatin should melt completely, leaving a clean substrate in 5-10 minutes.

Gelatin will spontaneously harden over time even if not exposed or sensitized, so I try not to get too far ahead in tissue production. Freezing tissue in ziploc bags will extend viability, but I have used unfrozen tissue a year old with success. Sensitized tissue must be used *immediately* after drying or else frozen in ziploc bags. Even frozen, sensitized tissue cannot be stored indefinitely. Frozen tissue may lose moisture (look for curling) and this will signifcantly alter the way it behaves and may even cause the gelatin to crack when flexed.

I have had to learn the hard way!
All my production work from last January has gone to waste( 30 sheets of beautiful carbon paper) I will now only produce material for immediate use to ensure no wasted time and materials.
Thanks for quick response.
Out of interest is there any preservative that could be used to prevent natural tanning?
DC

[pschwart]

Not that I know about. Did you test your tissue? Was it soluble?
Sensitized tissue: I take it from the freezer and thaw for a few minutes before exposing. Any tissue that is inadvertently left out of the freezer, even for a few hours, goes into the trash. The tissue speed and contrast starts to shift almost immediately so it will not provide consistent results.

Deardorff Dave, on 29 December 2011 - 03:28 PM, said:

I have had to learn the hard way!
All my production work from last January has gone to waste( 30 sheets of beautiful carbon paper) I will now only produce material for immediate use to ensure no wasted time and materials.
Thanks for quick response.
Out of interest is there any preservative that could be used to prevent natural tanning?
DC

[Howard Efner]

Deardorff Dave, on 29 December 2011 - 03:28 PM, said:

I have had to learn the hard way!
All my production work from last January has gone to waste( 30 sheets of beautiful carbon paper) I will now only produce material for immediate use to ensure no wasted time and materials.
Thanks for quick response.
Out of interest is there any preservative that could be used to prevent natural tanning?
DC

DC, The approximate shelf life of unsensitized carbon tissue is roughly 3-to-6 months. That lifetime is VERY dependent on storage conditions. Cool and dry is the best while warm and humid will cause the tissue so self-harden rather quickly. Also exposure to acid fumes and/or formaldehyde will cause the tissue to harden.

As far as I know, there is no preservative that can be added to extend shelf life.

There have been some proprietary formulation changes to B&S carbon tissue that do extend shelf life. I am not at liberty to discuss those changes.

[Jose Velez]

Until now I had no problems with unsensitized tissue nearly 2 months old, and not stored in the refrigerator, but I don't have extremes of temperature or moisture where I live.

Sensitized tissue is different, in normal weather conditions it holds 3 to 4 days, but I learned in the hard way that on hotter days it's unusable after 24 hours, roughly. Since I use spirit sensitizing which dries by itself in a couple of hours (or minutes when using a fan), I now sensitize for immediate usage only.

[Kymtman]

I have read several post and I have to wonder if one could use plexiglass as the tissue to "glop" for the sensitizeing. Thought that maybe it could lay flatter for the negative to print to and also to be cleaned for the next use, rather than throwing away.

Ron Tincher

[Kymtman]

Thinking of using a spray bottle to apply the dichromate, has this been done and will it work. One needs a light touch with a foam brush.

Ron Tincher

[pschwart]

Kymtman, on 04 February 2012 - 04:53 PM, said:

I have read several post and I have to wonder if one could use plexiglass as the tissue to "glop" for the sensitizeing. Thought that maybe it could lay flatter for the negative to print to and also to be cleaned for the next use, rather than throwing away.

Ron Tincher

Thinner stocks are easier to cut and work with, are cheaper, and can be reused, too (film stock, Yupo, mylar/polyester, RC paper). I do use acrylic sheets for squeeging, holding prints for retouching, and sometimes for temporary supports, ferrotyping, and other odd tasks. I have used sized 1/32" acrylic as a final support.

[pschwart]

Kymtman, on 04 February 2012 - 04:57 PM, said:

Thinking of using a spray bottle to apply the dichromate, has this been done and will it work. One needs a light touch with a foam brush.

Ron Tincher

I wouldn't want to spray dichromate into my work environment. I think you will find that brushing is the easiest way to get consistent results -- and safer.