Interesting palladium precoat experiment

[dpurdy]

I am printing Pt/pd today and as now it is winter and the gas furnace has been drying the house out the humidity in the basement is down in the low 40%s and my prints were coming out gritty looking. I have a variety of hoops I jump through to deal with that including presteaming and prewetting and prewetting with oxalic acid and they all help. But this morning I tried something I hadn't tried before. Instead of presteaming I measured out the normal volume of metal/iron with plain water and half the amount of Palladium in normally have in the mix. So I had a shot glass with 40 drops of water and 10 drops of Palladium and I coated an 8x10 the normal way with a brush. I let it sit and air dry till the gloss was long gone and it was starting to look almost dry, then I mixed my normal mix of metal/iron and coated it again and let it take a really long time to soak in before drying with a hair dryer. The resulting print is wow really nice, smooth, good contrast glowing whites and though not yet dry it looks like it has nice rich black.

just thought I would pass that along. Anyone else precoat with water mixed with Palladium?
Dennis

 

[Dana Sullivan]

You'd probably get the same results, while using less palladium if you did two half-strength coats. In our research, at B&S we've concluded that it's not so much the extra chemistry being laid down on your paper, but rather the act of coating it twice which makes the final prints look better.

The first coat will swell the fibers of the paper, and the second coat will more easily penetrate and stick inside the paper.

 

[Vaughn]

Sounds intertesting. If I read it right, you are using the same amount of chemicals one would use in a single coat...just split into two coating sessions. First coating is 40 drops water and 10 drops Palladium. The second coat is 20 drops iron and 10 drops Palladium (and some extra water?). Your wording was a little confusing.

One advantage I see in your method (if I got it right) is that one doesn't have to worry about any fogging (from light and/or oxidation of the iron salt) during the first coat and as it hangs to dry...since the sensitizer is only added in the second coating. One could do the first coating in regular (bright) room light. Other than this, it would seem to be the same method as Dana suggested.

Vaughn

 

[dpurdy]

Sounds intertesting. If I read it right, you are using the same amount of chemicals one would use in a single coat...just split into two coating sessions. First coating is 40 drops water and 10 drops Palladium. The second coat is 20 drops iron and 10 drops Palladium (and some extra water?). Your wording was a little confusing.

One advantage I see in your method (if I got it right) is that one doesn't have to worry about any fogging (from light and/or oxidation of the iron salt) during the first coat and as it hangs to dry...since the sensitizer is only added in the second coating. One could do the first coating in regular (bright) room light. Other than this, it would seem to be the same method as Dana suggested.

Vaughn

It is kind of a moot point because on drying the print had areas of weak looking black due to seemingly not enough pl/pd in the end. That was really the reason for the experiment. My B&S Cranes Platinotype was printing really gritty looking and steaming helped but not enough. I know from experience that I can pre wet with plain water and smooth out the tones but at the risk of not getting enough pl/pd soaked into the paper to give a good black. I thought perhaps if I mixed some Palladium into the pre wet water it would fix that, but it didn't. I guess I will try again what Dana suggests though in my experience it is easy to get streaks and uneven coating that way.

I remember the olden days, in the early 1990s when Crane's Platinotype was brand new. It would print unbelievably smooth regardless of technique and % of Platinum. It was a dream. Sometime around 1994 or 5 the dream became a nightmare and the paper wanted to get mottled and grainy whatever you did. I have still 800 sheets 11x14 from sometime around the turn of the century.

 

[colrehogan]

I am glad to read Dana's reply above. I too fight low humidity at this time of year. Last year, I found I was able to make prints that looked acceptable to me down to 35 % humidity. However, I prefer higher %RH when I can get it. I squeezed in my alt. print exchange prints last week since it was all of 46% RH in the house. Thank goodness for rainy weather in January.

 

[colrehogan]

sorry about the multiple posts.