Plague Spots: the Bane of Platinum Printers

[Ian Leake]

Ian Leake submitted a new resource:

(there was a url link here which no longer exists) - Plague Spots: the Bane of Platinum Printers

In recent weeks quite a few people have asked me how I deal with Plague Spots, so I thought a short article on these horrible things could be helpful.


Plague Spots are what I call the nasty, ugly black dots which appear on platinum and palladium prints. The small ones appear as tiny black specks, but the big ones can be several millimetres across.

If you look at a Plague Spot through an 8x linen magnifier you’ll see a dark central dot surrounded by a slightly paler,...

(there was a url link here which no longer exists)

 

[TheFlyingCamera]

Ian - in the many discussions I've read here and elsewhere as well as conversations I've had in person with other platinum printers, this phenomenon seems to raise its ugly head more with certain papers than with others. I can't recall ever seeing this on any prints I've made on Bergger COT320 - have you ever tried it? I remember there was a big batch of Arches Platine a few years ago that had a really bad case of plague spots, but that batch seems to have worked its way through the system and this is no longer the problem, or at least much less than it used to be. I also recall folks finding pre-acidification of their paper to help with this - a bath in 5% - 10% Oxalic Acid for 10-15 minutes seems to be a general consensus, with a preference for the weaker dilutions of the Oxalic Acid. Let me be clear- this process is not needed for all papers, and it may or may not resolve the plague spot problem. I don't know about Buxton, but Fabriano Artistico EW is one that definitely benefits from pre-acidification. I haven't tried it yet but I'll put good money on Rives BFK also needing pre-acidification, as I've gotten wierd blotchy areas on gelatin-sized but not acidified Rives BFK I was planning to test with gumover printing.

 

[Ian Leake]

Yes they may be effected by choice of paper, but I suspect that this is because of the way platinum reacts to different papers rather than any impurities in the paper.

Platinum and palladium are similar but not the same. For example, gelatin binds to platinum and stops it producing an image, but it doesn't bind to palladium. So a platinum-friendly paper would naturally show more plague spots than a paper which is not (assuming there's platinum in their coating).

Platinum also tends to create a more gritty image than palladium (which normally has a smoother transition of tones). It's possible, although this is speculation, that platinum naturally produces more spots than palladium.

Because most people nowadays print with pure palladium or palladium-rich solutions, and because so few papers are platinum-friendly, I wouldn't be surprised if this is not much of a problem for many printers.

Additionally, when prints have a full range of tones, or lots of dark areas, then many of the spots wouldn't be visible unless you know what to look for.

I'm interested in what you say about pre-acidification. When I tried this the number of spots on my prints increased dramatically, so I stopped quite quickly. That increase would point to one of two things, either: (1) increasing the acidity of the paper increases the frequency of spots; or (2) I was somehow introducing pollutants during the pre-acidification, and these led to more spots. I don't know which of these is correct and have no evidence either way.

 

[Robert Hall]

As an aside, I have been waiting for a new batch of Arches Platine from the manufacturer since September. The date is now pushed to the end of March. They are tight lipped about the delay, it could be that more cost effective papers are being made ahead of the Platine, but I have ordered quite a few sheets and will have one sheet shipped ahead of the others to test. Knocking on wood, I've never had problems with spots unless I have printed on the wrong (back) side of the platine paper.

 

[Peter Spangenberg]

Hi Ian-
Thanks for the info. My experience here is a bit different, but may lead to a third theory that readers can use. I printed Pt/Pd for a couple of years with no "black spot" problems whatsoever. Recently, I started having all kinds of spot problems (mostly small spots). I was advised by B&S that I may have developed a microscopic burr on my rotary trimmer that was allowing small metal shavings to be deposited on the paper. The paper I was using was from a batch I've used before with no problems, so the explanation sounded intrigueing/reasonable.

They suggested tearing the paper instead of cutting it on the trimmer. After a couple of less that perfect tearing attempts, what I did instead is aggressively brush the surface of the paper with a soft brush. This has worked for me and the problem has not returned.

 

[clay]

These blacks spots are a real pain in the rear until you learn how to fix them. That's for sure.

 

[Vaughn]

I remember reading a horror story about the black plague visiting a platinum printer. Usual tales of near-madness. Then illumination came to him as he pulled the chain for the light -- and small particles fell from the rusty chain...

 

[M Stat]

Dick Arentz describes (in his book) a useful method for eliminating black spots with the use of Titanium White water color paint. I have found that the offending spot may be reduced to the surrounding tone with a dilute solution, or a stronger white tone can be applied and later (after drying) can be filled in with the proper color/tone of watercolor paint (my preference being Lampblack). I have managed to salvage numerous old prints which I once thought were hopelessly "plagued".

 

[jean-claude mougin]

I am working with pure palladium and in 30 years I have never meet black point. Perhaps because I am working with a stock of old paper before 1985

Excuse my poor english

Jean-Claude Mougin

www.platine-palladium.com
www.platine-palladium.fr