Rust spots? Pt/Pd
I'm currently learning Pt/Pd. I've gotten better and better over the past few weeks with lots of reading and practice.
Last night, however, I ran into a problem. On every print I made, I got what looks like small rust spots. They are about the size of a pin head and are rust colored. I read something about "plauge spots" but I think this is different.
Could this be gunky developer? It does have some sediment in the bottom. I know you can re-use oxalate developer, but can you re-use ammonium citrate?
What are you using to cut the paper? Coat it? Any, I'm talking ANY, sort of small filing from a piece of metal can cause this. Sullivan has a story of someone who went through $500 in PT before realizing the spots were caused by a metal paper cutter blade leaving invisible amounts of metal on the paper.
Never cut paper, just tear it !! If you use a brush no metal part or you will have some spots even if you try to protect it with some Plastidip. I modified my "Magic brush" , you can see it here:
Yes, you can re-use ammonium citrate. The bottle I am using currently is basically 6-7 years old. It gets filtered through coffee filters when the "gunk" appears, as does the potassium oxalate. When the total quantity becomes too small, fresh is added.
I remember a story of someone plagued with "rust spots". After much frustration, the cause turned out to be a slightly rusty pull chain for the light above his work area!
Thanks for the responses. I use a small brush to even out the solution after I coat the paper with a glass rod. Brush usage is VERY minimal. The brush does have a metal ferrule. I assumed it didn't really matter as long as no metal came in contact with the solution. The paper isn't being cut by me, it's pre-cut 8.5x11 Crane's kid finish.
I'll give it a try with a Hake brush and see if the rust spots still appear.
A rust source could be the paper, paper moulds are often made of metal and sometimes iron particles can find their way into the paper add an acid and you get rust.
Chiming in late, sorry,
If it's not the tools & environment but the paper itself (which - maybe - you're heavily invested on), sulfamic acid can be used to dissolve rust particles in the paper...