Hardening albumen

[pdeeh]

I'm going to embark on a few tests with using albumin purely as a size (so, just egg-white and acetic acid, no salt), for Cyanotypes, Namias' sepia and possibly VDB,

I'm assuming that it will need a degree of hardening before coating with sensitiser, and the usual alternatives suggested for this are ageing, heating (ironing), steaming, or an isopropanol bath.

It'll be easy and almost zero cost to run an iron over a few sheets of sized paper (I'd use a heavy Kraft paper to protect it), but I also wondered if there were other options, or different technical advantages or disadvantages to the various established methods.

Is there something particular about isopropanol that triggers the coagulation, or will pretty much any old alcohol do (e.g. methanol, ethanol), for instance?

 

[chrisaisenbrey]

I can’t answer your questions. I can jus tell you what I do to harden albumin:


I use albumin to prepare plastic sheets for double transfer carbon prints. For this I first put the plastic sheets in albumin solution and transfer them directly afterwards in a solution of chrome alum (Chromium(III) potassium sulfate). Some ml of 2% chrome alum solution per liter is fine.


I’ve tried the isopropanol method, but then the gelatin layer was sticking too well and the transfer to the final support was difficult.


I actually doubt that isopropanol or heat harden albumin in the sense that crosslinks are formed. I guess the proteins are rather denaturated and loose their water solubility.

 

[pdeeh]

Thanks for the thoughtful answer Chris.

Yes I had wondered about the mechanism of hardening, but my knowledge of chemistry is paper-thin (pun unintentional).

Interesting that Chrome alum seems to work ok, it makes me wonder whether formaldehyde would also work as both can also be used for hardening gelatin. Of course the fact that both gelatin and albumin are both proteins doesn't mean that they will react the same.

 

[pschwart]

I'm going to embark on a few tests with using albumin purely as a size (so, just egg-white and acetic acid, no salt), for Cyanotypes, Namias' sepia and possibly VDB,

I'm assuming that it will need a degree of hardening before coating with sensitiser, and the usual alternatives suggested for this are ageing, heating (ironing), steaming, or an isopropanol bath.

It'll be easy and almost zero cost to run an iron over a few sheets of sized paper (I'd use a heavy Kraft paper to protect it), but I also wondered if there were other options, or different technical advantages or disadvantages to the various established methods.

Is there something particular about isopropanol that triggers the coagulation, or will pretty much any old alcohol do (e.g. methanol, ethanol), for instance?

Albumen is easily hardened with isopropyl alcohol. I use 70% isopropyl. You can immerse the paper for just a few seconds or use a foam brush or roller to instantly harden the albumen. If you use multiple coatings of albumen you need to harden between coats. I did try hardening carbon supports sized with albumen using a dry mount press; I found it time consuming, unreliable, and often left the papers with a yellow tint. Hardening with isopropyl is simple, cheap, and fast.

 

[CMB]

chrisaisenbrey wrote:

[QUOTE

I use albumin to prepare plastic sheets for double transfer carbon prints. For this I first put the plastic sheets in albumin solution and transfer them directly afterwards in a solution of chrome alum.
I’ve tried the isopropanol method, but then the gelatin layer was sticking too well and the transfer to the final support was difficult.

[/QUOTE]

Excess albumen will cause bubbles, pigment film will stick to temp and final transfer will be difficult (incomplete). The plastic temporary support sheets should be rinsed in cold water immediately after coating leaving a very thin layer of albumen. Let dry, and then coat with Iso-alcohol (my pref is for 91%).

Charles

 

[chrisaisenbrey]

chrisaisenbrey wrote:

[QUOTE

I use albumin to prepare plastic sheets for double transfer carbon prints. For this I first put the plastic sheets in albumin solution and transfer them directly afterwards in a solution of chrome alum.
I’ve tried the isopropanol method, but then the gelatin layer was sticking too well and the transfer to the final support was difficult.

Excess albumen will cause bubbles, pigment film will stick to temp and final transfer will be difficult (incomplete). The plastic temporary support sheets should be rinsed in cold water immediately after coating leaving a very thin layer of albumen. Let dry, and then coat with Iso-alcohol (my pref is for 91%).

Charles[/QUOTE]

Thanks Charles, perhaps I try isopropanol again. However I’m quite pleased with the chrome alum method.


Would be interesting whether both methods result in surfaces with different properties. (e.g. more or less hydrophobic/hydrophilic)


I actually not really “coat” the plastic sheets I rather immerse the plastic sheets in a diluted solution of albumin. The resulting layer is rather invisible.


Chris

 

[CMB]

chrisaisenbrey wrote:
[/QUOTE]


I actually not really “coat” the plastic sheets I rather immerse the plastic sheets in a diluted solution of albumin. The resulting layer is rather invisible.


[/QUOTE]


There are several ways to "coat" PET sheets with albumen: tray, dip, brush, roller. In any case, the sheet should be (vigorously) washed in a tray of cool water before hanging to dry. In this way, you will be left with a very much thinner (and more usable) coating of albumen than if you skip the rinse.

Charles