Basic sizing questions for salted paper

I'm interested in exploring salted paper prints, and I like the look of the final results with gelatin and/or agar-agar sizing so would like to start with them even though they're more complex than simple salt solutions. I've been doing a bunch of reading but so far haven't been able to find the answers to these seemingly basic questions.

1. With gelatin and agar-agar sizes, should I coat the entire sheet or just the area where the image will be (plus, of course, a bit of border area)? It makes sense to soak the entire sheet for simpler salt-solution sizes, but these sizes are typically brushed on. Basically, is there any issue with the final print if I don't size to the paper edges?

2. The agar-agar sizing recipe in Chapter 9 of Christina Anderson's book requires boiling. Can I use stainless steel?

I am no expert here as the large majority of my salted-paper prints are unsized. I have experimented with sizing using arrowroot starch or gelatin a bit, so take these comments with that caveat.

I have had better results using a smooth foam roller to apply sizing than I get with brushing it on.

When I coat, I don't worry too much if I miss a small spot on the edge of the paper, but I do try to coat the entire sheet. Remember that paper curls and buckles, etc. because the two faces of the paper react differently to moisture. Thus, I am hoping to avoid extra problems by having one side coated un-uniformly. Not sure that this is a real problem as I have not done a direct test.

As for using stainless steel, again no direct experiments. However, my chemist's intuition say it would be better to use glass than metal. With glass there is no possibility for the vessel to add redox active contaminants (i.e. metals) to you sizing. Again. I am not sure this is a real problem in practice, but it is one possible source of variation that is easy enough to avoid. My first rule of alt processes is "Avoid as many sources of variability as possible. There are plenty to go around as it is!".

fgorga said:

I am not sure this is a real problem in practice

Click to expand...

I don't think so. The impact of the hypothetical addition of contaminants due to the use of stainless steel for boiling a sizing solution is likely to be less than the risk of contaminants present in the chemical components used. Particularly the agar-agar, but depending on source and purity also the salt, silver nitrate and even water used.